Insects, the most abundant group of organisms, are widely distributed throughout the world. They inhabit diverse habitats and serve many important functional roles in the ecosystems. Damage from exotic insects is increasing all over the world, because of expanding international air transport, tourism, and the trade in agricultural products. At the same time, areas disturbed by human activity cover a greater area each year. Procedures to control the introductions of exotic species tend to conflict with policies promoting international trade and travel. The most effective way of reducing the entry of exotic insects would be to reduce trade and travel, but this approach is politically unacceptable. If increased international trade and travel are encouraged, as is the worldwide trend, the paths of movement of exotic species will obviously increase in number and variety (Cox, 1999).
Insect pest fauna consists of both endemic and exotic species. Endemic species may become pests when a new crop species or variety is planted in an area (Elton, 1958), whereas immigrant species may become pests after they have successfully colonized the new territory (Pimentel, 1986). Many of these introduced species are the most serious agricultural pests (Sailer, 1983).
Alien species may be described as animals, plants or micro-organisms which may enter a new habitat not by its own effort, but could be introduced by human activity. The Convention on Biological Diversity (CBD) defines an alien species as a species, subspecies or lower taxon (includes any of its part that might survive and reproduce) introduced outside its natural past or present distribution (CBD, 1992). It is invasive if it causes any form of damage. In the context of the CBD, it is a species that threatens biological diversity but in the broader context it has negative impacts in any areas such as agriculture, human development as well as human health (CBD, 1992).
One area of particular concern is the current global traffic in agricultural items, especially fresh produce. Consumer demand for fresh fruits and vegetables is increasing. In recent times, Africa and for that matter, Ghana has witnessed some Invasive Alien Species (IAS) causing a lot of havoc to her agriculture, the environment, and trade. Some IAS such as the cassava mealy bug, Phenacoccus manihoti, the Africa Invader fly, Bactrocera (= invadens) dorsalis, the White fly, Bemisia tabaci and the Larger Grain Borer (LGB), Prostephanus truncatus, are a few causing serious economic hardship to farmers, exporters and the country at large. Both adults and larvae of Protesphanus truncatus feed on the loosed grains and the cob of maize (with or without the sheath) before and after harvest in storage, causing extensive damage (Boateng and Ayertey, 1996). Adults also feed on dry cassava and wood. Losses of maize stored in cribs have been found to be as high as 34% after 3 – 6 months of storage, which is 3-5 times higher than losses caused by other pests (Kossou and Bosque-Perez, 1998).
Bactrocera dorsalis was also introduced to Africa and found in Ghana in 2005 causing severe damage to the fruit industry (Billah, et al., 2006). Ghana lost a lot of foreign exchange due to the ban on the exported of mangoes to other countries due to this invasive fruit fly which is a quarantine pest. Virtually all countries in the Sub-Saharan African region are affected by IAS. In 2004, the International Union for Conservation of Nature (IUCN) – the World Conservation Union (IUCN) identified 81 IAS in South Africa, 49 in Mauritius, 44 in Swaziland, 37 in Algeria and Madagascar, 35 in Kenya, 28 in Egypt, 26 in Ghana and Zimbabwe, and 22 in Ethiopia (IUCN/SSC/ISSG 2004).
International trade has been responsible for the inadvertent introduction of many exotic (nonnative) insect pests and plant pathogens, of which several have become highly invasive and caused serious environmental and economic imparts to multiple habitats worldwide (Mack et al., 2000). With the current increase in international travel, the movement and incidences of exotic species have increased both in numbers and new species (increase species diversity). Areas of particular concern are agricultural products, especially fresh produce such as vegetables, ornamental, stored grains and timber. The principal agreement governing international movement of plant pests is the International Plant Protection Convention (IPPC). The agreement prevents international movement and introduction of invasive pests and promotes appropriate measures for their control. The scope of the IPPC extends to protection of natural flora and covers direct and indirect damage by pests (IPPC, 2005).
The main risk pathways for movement of serious Phytosanitary pests crossing international borders include:
i. Imported cargo involving trade in plants and plant products including potentially contaminated goods such as used agricultural, military and earthmoving equipment.
ii. Passenger movement at airports and seaports including personal effects and the vessel itself.
iii. International mail exchange, and
iv. Unregulated movement across inter – country borders.
Global merchandise trade was valued at $8.99 trillion in 1948 (Anon, 2006), while in 2012 world trade reached $18.0 trillion, indicating an increase of about 200% between the period (International Trade Statistics Yearbook, 2012). International aircrafts and vessels, including cruise ships, itinerant yachts and cargo ships present a risk pathway as they can carry food wastes, refuse in holds and galleys, imported cargo of bulk grain, timber products, and stock feeds; and may also have live plants on board. In addition, the vessels or conveyances themselves have the potential to introduce hitchhiking pests (Dobbs & Brodel, 2004). Containers pose a novel problem in that, in addition to the goods transported, alien flora and fauna can be associated as stowaways inside or on the surface of the container (Hulme et al., 2008).
1.0.2 Fruit Production
Fruits production is one of the fastest growing sectors of the horticulture industry in Africa (Weinberger and Lumpkin, 2007). The sector contributes to poverty alleviation by promoting food security while helping to increase total export earnings for African countries. Throughout Africa, several fruit crops are grown for both domestic and export markets. The major ones include mango, citrus, papaya, avocado, banana, and the cucurbits. In 2007, the horticulture industry generated over US$ 16 billion in foreign exchange from exported commodities and over US$ 6,500 million domestically to the continent; directly and indirectly employing over 40 million people (World Bank, 2008). More than 50% of the production volume is affected by fruit fly infestation. Currently, the key pest constraint for the increased and sustainable production of fruit crops in Africa is infestation by the fruit flies (Jaeger, 2008). Tephritid fruit flies have been recognized as one of the most economically important group of insects which pose serious threat to the horticultural industry in Sub-Saharan Africa (SSA) (Ekesi and Billah, 2006). Fruit fly infestation has led to heavy losses in yield and quality of fresh fruits, and restrictions to quarantine-sensitive throughout Africa.
Sub-Saharan Africa is the home of several species of highly damaging fruit flies. For example, on mango, the results of several surveys across SSA show the crop is attacked by native fruit fly species such as Ceratitis cosyra, C. quinaria, C. fasciventris, C. Rosa, C. anonae, C. capitata. Traditionally, yield loss on mango due to native fruit flies can range between 30% and 70% depending on the locality, season and variety (Lux et al., 2003).
Although Africa is known to be the place of several fruit fly introductions and establishments worldwide (the most notorious species being the Mediterranean fruit fly, C. capitata), with the intensification of the fruit trade, the continent has also become highly vulnerable to introduction of alien fruit fly species. Bactrocera invadens was detected and described for the first time in Africa as a junior synonym of B. dorsalis (Drew et al., 2005). In 2006, the Solanum fruit fly B. latifrons, a primary pest of solanaceous crops was detected in Tanzania. The melon fly B. curcubitae has also been in Africa for years without a clear date of introduction. Among all the native and exotic fruit fly species, one species, B. invadens, that is commonly referred to as the African invader fly, is thought to be responsible for causing extensive economic losses to fruit crops throughout Africa since its first detection in 2003. The rapid spread and devastating impact of B. invadens in SSA has been a matter of serious concern to the horticultural industry.
1.0.3 Vegetable Trade between Ghana and the European Union
Total vegetable trade between Ghana and the European Union accounts for about USD 7m. There is a decrease of almost 50% in imports since 2008. The main reason is that a number of exporters stopped their activities since they were confronted with stricter phytosanitary requirements which were challenging for some exporters. The majority of the products are shipped to the UK (91%). Chilli (Pepper) represents the largest share with a total value of USD 3.7m. Exports were between 1,500 and 3,000 tons. Other vegetables like okra and bitter gourd are not registered as such in the international trade statistics, but are included in the HS code 070990 (vegetables, fresh or chilled – not elsewhere specified) prior to 2011 and HS 070999 (fresh or chilled vegetables not elsewhere specified) from 2012 onwards.
Chillies are used for the production of pepper spray. The import of fresh chilli peppers in the European market decreased from 96,700 tons in 2009 to 85,600 tons in 2013.
This decrease in exports from Ghana is due to the fact that harmful organisms were found on our products exported to the European countries.
There has been continuous and increasing number of interceptions by European Union (EU) Member States.
Table 1. Interceptions from Ghana by European Union Member States
No. Year Number of Interceptions
1. 2011 83
2. 2012 65
3. 2013 164
4. 2014 330
5. 2015 117
6. 2016 37
7. Jan, 2017 0
8. Feb. 2017 1
9. Mar. 2017 0
10 April 2017 0
11. May 2017 0
12. June 2017 0
*The sums indicated do not necessarily correspond to the number of interception notifications sent by EUROPHYT to the exporting country. One notification may contain interceptions of several plants or harmful organisms shown individually in the tables.
The most commonly intercepted organisms include non-European Tephritidae (fruit flies), Thrips palmi and other Thysanoptera (thrips), White flies, Bemisia tabaci, both IAS and egg-plant borer, Leucinodes orbonalis. In addition, between 2008 and 2010 there were 24 notifications of interception of citrus blackspot (Guignardia citricarpa) (Europhyt, 2014). These harmful organisms were found mainly on exported vegetables and fruits of mango (Mangifera indica), garden eggs (Solanum aethiopicum), aubergine and/or ravaya and other aubergine vegetables types (Solanum melongena), peppers (Capsicum frutenscens), karela (Momordica sp.) and citrus from Ghana.
1.2 Problem Statement
Global changes in trade and population migration are causing higher demands for agricultural products, with new plants and plant products being imported from new global trading partners often with limited biological knowledge of the associated pest risks. The means of introduction and potential establishment are called ‘pathways’,’ defined as ”any means that allows the entry or spread of a pest” (FAO, 2002). Examples of human-mediated pathways include cargo, passengers, and conveyances entering a country or place where no such pests exist. There is no documentation in the case of Ghana as to which human-mediated pathways invasive species enter into Ghana most.
To help minimize the threat, cargo, passengers, and conveyances are inspected at entry ports of most countries by officers of Plant Health Inspection Services or Plant Quarantine officers. Despite the best efforts of Plant Quarantine Division of Ghana, non-indigenous species continue to be introduced into the country and to become established.
The volume of goods imported into Ghana is likely to bring along a range of new Phytosanitary pest risks. These risks are often associated with cargo pathways for pests’ unknown to the country. There is compelling evidence, based on global trade and movement patterns, that the threat of invasive alien species to biodiversity is increasing (Hulme, 2009).
According to International Standards for Phytosanitary Measures (ISPM) No. 6, 1997, (FAO), 2011) specific surveys fall into one of the three categories of detection, monitoring and delimiting surveys.
The purpose of this study is to undertake a survey to identify insect pests associated with imported commodities in the three entry points in the Southern sector of Ghana, and focus will be on all insects’ pests associated with the imported commodities in these geographical areas. The challenge is that there is little documentation on insect pest’s interceptions into the country. This research therefore aims at conducting a survey of insect fauna associated with imported commodities of quarantine concern at the selected entry points in Southern Ghana.
1.3 Research Objectives
The main objective of the study is to conduct a survey on insect pests associated with some imported commodities entering Ghana.
Specifically, the study seeks;
i. To identify various insect pests that come through the three major Southern entry points of Ghana (Aflao border, Kotoka International Airport (KIA), and Tema Harbour) in association with some agricultural commodities.
ii. To established the countries from which these insect pests, associated with these agricultural commodities come from.
iii. To establish whether the identified insect pests through Ghana’s three major entry points are the same as those EU intercepts on agricultural commodities from Ghana.
iv. To compare the diversity of pests on imported agricultural commodities from the three major entry points.
1.4 Research Questions
Based on the objectives, the study was guided by the following research questions:
i. Which insect pests are imported through the three major Southern entry points of Ghana (Aflao border, Kotoka International Airport and Tema Harbour) in association with agricultural commodities?
ii. From which countries are these insect pests coming from through the three major Southern entry points of Ghana.
iii. Is there any relationship between the identified insect pests and those EU intercepts on agricultural commodities from Ghana?
iv. Are there differences in the type of the insect pests that are imported through the three major Southern entry points of Ghana, in association with agricultural commodities?
v. Are there differences in the quantity of the insect pests that are imported through the three major southern entry points of Ghana, in association with agricultural commodities?
1.5 Scope of Study
The study covered the three entry points through which agricultural commodities are imported. These entry points are the land port entry point at Aflao border, the sea port entry point at Tema Harbour and the airport entry point at Kotoka International Airport (KIA). The study focused on imported agricultural commodities such as vegetables and fruits through these entry points from 4th November, 2015 to 4th May, 2016.
Lack of data has been most apparent for Ghanaian ports, in terms of number of ships, aircrafts and vehicles’ visits and volume of imported commodities. Documenting all biota of our ports will help identify native species, and so elucidate the true extent of nonindigenous species introductions which will probably take decades to research into owing to the limited amount of funding sources if not done now.
Ghana is facing a lot of challenges in terms of introduction of invasive pests which are getting established and spreading. Some of these insects’ pests are non-native to Ghana. These are causing devastating havoc to our agriculture, livelihood of our farmers, economic loss to families and threatens our survival in terms of food security.
In 2016 the Fall Army worm (FAW) Spodoptera fugiperda was introduced into Ghana and by the close of the year it has spread all over the country and caused devastating havoc. A lot of resources that could have been used for other important pressing issues, was used to control and manage the spread of the insect pests. In 2017 another insect pest found its way into Ghana from East Africa, the tomato leaf miner, Tuta absoluta, we are battling with this insect pest as well.
The above studies show that the trend has changed and insect pests are using these pathways into countries, getting established and causing severe damage. Are we going to lose the horticultural contributions to the economy of Ghana, the market shares and the implication for the exporters, livelihoods and the sector at large due to insect pest infestations? This calls for concern to protect life, income and trade. This study is necessary since none has been done in Ghana to know the biodiversity nature at these entry points.
The study will also help form the basis for an intercepted record list to begin with and also to know the invasive species coming into Ghana through these pathways and whether some has already established which we do not know but may have been causing serious damage to Ghana’s agriculture. Some of the intercepted organisms by the EU member states point to the fact that we might be exporting invasive alien species not of this origin. Lack of data has been most apparent for Ghanaian ports, in terms of number of ships, aircrafts and vehicles’ visits and volume of imported commodities. Documenting all biota of our ports will help identify native species, and so elucidate the true extent of nonindigenous species introductions which will probably take decades to research into owing to the limited amount of funding sources if not done now.?
2.0 LITERATURE REVIEW
2.1 Insect Pests Associated With Agricultural Cargo In International Trade.
The movement of animals and plants began decades ago when people started travelling from one country to another country and from one continent to the other to look for food and in search of economic gains. As international travel by sea and air increased, the frequency of insect species transported around the world also rose.
The ever increasing rate of invasions has largely been attributed to the upward trend in human mobility and international trade (Mack et al. 2000). Information on the importance of various invasion pathways is essential for developing effective biosecurity strategies (National Research Council 2002). There has been substantial progress in characterizing invasion pathways of aquatic organisms (Gollasch 2002, Maki and Galatowitsch 2004) and of terrestrial invaders associated with commercial cargo operations (e.g., Haack 2001, Stanaway et al. 2001, McCullough et al. 2005); however, efforts to study alien species associated with passenger travel are limited.
International trade has been recognized as the major channel by which non-indigenous insect pests enter the United States (National Plant Board, 1999). Pimentel et. al. (1999) estimated that more than 4,500 arthropod species have been introduced into the United States, 95% of which were accidental. Many species entered through agricultural and non-agricultural cargo’s, on produce or plant propagative materials in travelers’ baggage, and as hitchhikers on airplanes, trucks and ships. For example, Frank ; Mc Coy estimated 11,500 native species, and more than 949 species were introduced accidentally in Florida. Frank ; Mc Coy, (1995), successfully established and became invasive in the state. Florida’s proximity to Central America, South America, and the Caribbean has become the major transit point for trade and commerce between the United States and these countries (Caton et.al. 2006). With,
1. Increasing international and domestic travel within and across its borders.
2. Growing numbers of entry ports
3. Large numbers of export and import markets and
4. Improved access to foreign markets.
Florida became vulnerable to insect pest invasion. An estimated 55% of all their goods shipped between the United States and Central America, 44% of U.S. cargo bound or arriving from the Caribbean and, 30% of the trade with South America passes through Florida (Caton et.al. 2006). Experts say at least one new insect enters the state each month, potentially threatening agricultural crops and native species (Crabbe, 2006, Frank & Thomas, 2004). Today, Florida’s most important crops such as corn, peppers, and snow beans owe their existence to constant vigilance by the Florida Department of Agriculture (FDACS), United States Department of Agriculture (USDA) and Customs ; Border Protection Agricultural Specialists (CBP); all three agencies worked together to keep many dangerous pests out of the state. Diligent Inspectors worked alongside the Customs Officers, met all arriving vessels that arrive by land, sea, or air. The Officers inspected cargo and passengers’ baggage, the holds of vessels, cabins, crew’s quarters and store rooms of vessels themselves to keep out potential insects hitch-hiking on commodities or on the vessels. The interception of insects, diseased plants, and disease causing organisms was a daily occurrence. Numerous attempts were made to smuggle plants into the state and each year the ever increasing array and speed of commercial and private means of transportation added to the difficulty of detecting and excluding foreign pests.
2.2 Exported Commodities
According to Ghana Export Marketing and Quality Awareness Project Appraisal Report (2005) Ghana’s traditional major export commodities are gold, cocoa and timber. Gold and cocoa contributed more than 80% of foreign exchange. Cash crops, comprising primarily cocoa, timber and others (coconuts, other palm products, shea-nuts and coffee) provided about two-thirds (2/3) of export revenues, estimated at USD $3.01 billion in 2004. The major export partners of Ghana are: Netherlands (11%), United Kingdom (10.6%), France (7.6%), Germany (6.2%), Japan (5.2%), Italy (4.6%), Nigeria (4.4%) and the United States of America (4.2%). The combination of unstable cocoa production, due to unfavorable weather conditions and the recent declines in world prices for cocoa and gold has reduced export earnings.
With the decline in cocoa and gold world prices, the Government realized the need for diversifying its sources of foreign earnings into the production and export of horticultural products, which in turn will improve the livelihood of rural populations. By means of incentives, the government has engaged in promoting Non-Traditional Exports (NTE) in the agriculture and fishing sectors since 1983. The project has been very successful in the agricultural sector, with the rapid development of export activities for non-traditional agricultural products including fruits such as pineapples, mangoes, papaya, and vegetables.
2.3 Non Traditional Exports (NTE)
Total export value of Ghanaian non-traditional products reached $ 2,463 million USD. A decrease of 2.3% over the year 2016 and an average annual growth of 1% during 2012-2016. Burkina Faso is the largest export destination with 10.1% share of total non-traditional exports in 2016. It is the main destination for plastics, while also present in the top three destinations in other sectors like aluminum/iron and steel products. Besides cocoa products, also prepared foods and beverages, oil seeds and nuts and plastics are large export sectors for Ghana. All of these sectors have other main export destinations (respectively U.K., Vietnam and Burkina Faso). Pharmaceutical products (+190.6%) reached the highest average annual growth over 2012-2016. Largest export partner for pharmaceutical products was Senegal in 2016. Other good growing sectors over this period include animal or vegetable oils (+22.8%), as well as oil seeds and nuts (+13.9%) (Ghana Export Promotion Authority, 2017).
In general, the contribution of NTEs to the growth of GDP in Ghana has been modest showing a positive trend of growth. On the average the NTE sector contributes about 6% per annum to GDP since year 2000. The share of the sector in 2000 to the growth of GDP was 8.05%. Though at a declining rate, the sector contributed positively to GDP till it stagnated at 4.7% in 2007. This marked the period before the Global Financial Crisis where the sector’s contribution declined by 9.39% but still contributed 4.68% to GDP growth. Ghana’s GDP also plummeted from US$28,530.000 million to US$25,980.000 million at the same period.
The European market has been the main market destination of Ghanaian NTEs, absorbing about 82.6% of the total agricultural exports. In Europe, the United Kingdom is the primary destination, accounting for about 42.1% of total export earnings, followed by Belgium, France, Germany and Italy. Other destinations are ECOWAS countries with about 17%.
During the period 2010-2014, horticultural products, led by pineapple, have been the biggest contributor to Agricultural NTEs, ranging from 36 to 39%, and accounts for about 36% of the total value of export earnings. The next major contributors are fresh papayas, mangoes and Asian vegetables (tinda, okra, chillies and pepper). Volumes and export earnings have significantly increased in the period of 2006-2010. This started declining due to interceptions by the European Union pest alert systems. A lot of notifications were sent to Ghana NPPO and Ghana placed a temporary ban on these export that led to the decline in production and exports.
Vegetable exports dropped from 11,658 in 2011 to 1,960 in 2012 respectively and in 2013 no data was recorded showing clearly the devastating effect of pests causing a decline in exports of vegetables.
Ntow in 2006 noted that, one of the biggest problems confronting vegetable farmers in Ghana was disease and pests which ravage their crops (Ntow et al., 2006).
Fruits grown were also confronted with insect pests, mostly fruit flies. Losses due to fruit flies in Ghana was estimated at between 60% and 85% of the crop, depending on the cultivar and season (Billah et al., 2006). This deprived communities of an important source of nutrition (particularly vitamin A) and lead to the loss of highly valuable market share. Apart from pineapples, most horticultural products are susceptible to fruit fly attack. Fruit flies can also trigger a quarantine restriction in many countries, and their detection in exports leads to complete banning of a crop by importing nations.
2.4 Banned Agricultural Products Exported To EU
Ghana began exporting mangoes to the EU in 2004, with a total export of 177 tons, making mangoes one of the country’s largest exports of fresh produce to the EU. However, in 2005, a ban was placed on Ghanaian mangoes to South Africa (it remains in force) for fear of potential invasion by B. Invadens.
The most recent audit (Ref: DG (SANTE)/2015-7635) took place in April 2015, in order to evaluate the system of official controls for the export of plants and plant products to the EU (hereafter referred to as the “previous audit”). The audit identified shortcomings in the phytosanitary export certification system and interception numbers, which had risen consistently from 2012, continued at a high level during the months following the audit.
Due to the outcome of the first two audits and the high number of interceptions, measures were taken to address the risk posed by the import into the EU of specified commodities originating in Ghana. Commission Implementing Decision (EU) 2015/1849, adopted in October 2015, temporarily prohibited introduction into the EU of five commodities namely (Capsicum, Lagenaria, Luffa, Momordica and Solanum L., other than S. lycopersicum L.)
2.5 Insect Pest Introduction
A variety of insects, weeds, disease causing organisms such as fungi and viruses, as well as other potential pests has been purposefully and inadvertently introduced into North America (CAST, 1987). Many of these transplants have adapted to their new environment and the North American ecosystem has been modified by the non-native species that have successfully established and, in some cases, became invasive as they out competed native species for resources. Many non-native plant species such as corn, wheat, and rice have become economically important agricultural food crops in the United States (Simberloff, 2000). It has been estimated 25% of the world’s pathogens and 10% of its insect species pose significant threats to its agriculture (Huber et.al. 2002) but, this is rapidly changing. Insect species such as the Mediterrean fruit fly (Ceratitis capitata), and the Oriental fruit fly (Bactrocera dorsalis) are known pests in other countries and, if introduced into the United States, could adapt in those parts of the country with similar ecological conditions to their native range. Should either of these fruit flies become established in North America they could become damaging pests to a wide range of hosts, and would require extensive control and eradication efforts (Newell, 1928), The United States is regarded as a “melting pot” of ethnic groups and a “stew” of crops and insect pests (Huber et.al. 2002). Over the past three decades, agricultural, social, and industrial activities have altered the natural balance of the country’s ecosystems. The rate of introduction of potential pest insects has accelerated significantly as a result of:
1. Increasing commercial and recreational travel by air, land and sea,
2. Growing numbers and expanding ports of entry to facilitate larger vessels such as cargo ships.
3. Expanding export and import markets.
4. Improved access to foreign commodities.
In addition, because of the large volume of commercial and recreational travel within and across its borders, the continental United States has been, and continues to be, especially prone to insect pest introduction. Consequently, throughout the past two decades, a greater number of invasive non-indigenous insects and pathogens such as Asian cycad scale, Aulcaspis yasumatsui, citrus greening (Huanglongbing), emerald ash borer, Agrilus planipennis, and laurel wilt disease caused by the fungus, Raffaelea lauricola and vectored by the beetle Xyleborus glabratus have become established in the United States contributing to economic losses in excess of $137 billion per year (Pimentel et.al. 1999, Ciesla, 2002).
2.6 Damage and Loses by Insect Pest
In the period from 1906 to 1991, the documented losses from 79 harmful exotic species amounted to $97 billion, which translated to $1.1 billion per year over this period (OTA, 1993). These were mostly losses due to control costs and damage to marketable goods. Recent estimates of Pimentel et al. (2005) showed that the economic damages and the associated control costs from more than 50,000 existing pest and invasive species in the U. S. amounted to $120 billion per year – broken down to $34.5 billion for plant invasive; $25.7 billion for microbes; and $59.8 billion for animals. Pimentel et al. (2005) also considered these as conservative estimates because they did not include monetary values of extinction of native species, losses in biodiversity, ecosystem services and aesthetics. The total cost would be significantly higher than the $120 billion per year if these factors were taken into account.
There are also cost estimates of the potential damage from specific invasive species in several other countries that are available in other literatures.
Indirect losses caused by fruit flies results from quarantine restrictions that are imposed by importing countries to prevent entry and establishment of unwanted fruit fly species (STDF, 2009). The effect of these pests has led to barriers to trade in fresh fruit commodities, costly surveys, and control and eradication programs throughout the world and thus, imposing limits on the export market (Ekesi and Billah, 2006). Rejection by European markets is increasing largely because with global trade and passenger travelling, they are easily trans located and the risk of majority of African fruit flies as key and potential quarantine pests is becoming increasingly realized (Ole-Moi Yoi and Lux, 2004). Quarantine regulations imposed by an importing country can either deny a producing country a potential export market, or force the producer to carry out expensive disinfestation treatments against fruit flies (White and Elson-Harris, 1992). These restrictions seriously threaten the income, food security and livelihood of millions of families that produce and sell fresh fruits and vegetables in Ghana.
Table 2 Volume of Main Agricultural Non-Traditional Exports
Commodity/ Year 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 % Change (2013/2012)
Pineapple 45,145 71805 46,694 60751 40456 35134 31567 40141 45057 41212 40095 -2.70
Yam 7973 16169 18377 20297 19716 20842 17571 19485 27393 25079 5230 -79.10
Oranges 4307 742 5846 6283 3674 10991 11028 10729 3812 7589 8233 8.50
Vegetables 4369 607 0 – 6 n/a 2342 3695 11658 1960 – -100.00
Banana 364 725 1117 44098 52069 69779 47613 64202 63761 60425 8656 -85.70
Mangoes 234 376 407 182 824 858 435 291 869 1222 1789 46.40
Pawpaw 1917 3752 3212 1912 1194 968 891 812 920 426 1119 162.70
Culled from: Ghana Export Promotion Council (GEPC), Accra.
2.7 Sampling Methodology
According to ISPM 31, Inspection of consignments of regulated articles moving in trade is an essential tool for the management of pest risks and is the most frequently used phytosanitary procedure worldwide to determine if pests are present and/or the compliance with phytosanitary import requirements.
It is usually not feasible to inspect the entire consignments, so phytosanitary inspection is performed mainly on samples obtained from a consignment. It is noted that the sampling concepts presented in this standard may also apply to other phytosanitary procedures, notably selection of units for testing.
Sampling of plants, plant products and other regulated articles may occur prior to export, at the point of import, or other points as determined by NPPOs.
It is important that sampling procedures established and used by NPPOs are documented and transparent. Sampling methodologies used by NPPOs will depend on the sampling objectives (for example, sampling for testing) and may be solely statistically based or developed noting particular operational constraints. Methodologies developed to achieve the sampling objectives, within operational constraints, may not yield the same statistical confidence levels in the results as fully statistically based methods, but such methods may still give valid results depending on the desired sampling objective. If the sole purpose of sampling is to increase the chance of finding a pest, selective or targeted sampling is also valid. (ISPM 31, 2016)
2.7.1 Simple Random Sampling
Simple random sampling results in all sample units having an equal probability of being selected from the lot or consignment. Simple random sampling involves drawing the sample units in accordance with a tool such as a random numbers table. The use of a predetermined randomization process is what distinguishes this method from haphazard sampling.
This method is used when little is known about the pest distribution or rate of infestation. Simple random sampling can be difficult to apply correctly in operational situations. To use this method, each unit should have an equal probability of selection. In cases where a pest is not distributed randomly through the lot, this method may not be optimal. Simple random sampling may require greater resources than other sampling methods. The application can be dependent on the type and/or configuration of the consignment. (ISPM 31, 2016)
2.7.2 Selective or Targeted Sampling
Selective sampling involves deliberately selecting samples from parts of the lot most likely to be infested, or units that are obviously infested, in order to increase the chance of detecting a specific regulated pest. This method may rely on inspectors who are experienced with the commodity and familiar with the pest’s biology. Use of this method may also be triggered through a pathway analysis identifying a specific section of the lot with a higher probability of being infested (for example, a wet section of timber may be more likely to harbour nematodes). Because the sample is targeted, and hence statistically biased, a probabilistic statement about the infestation level in the lot cannot be made. However, if the sole purpose of sampling is to increase the chance of finding a regulated pest(s), this method is valid. Separate samples of the commodity may be required to meet general confidence in detection of other regulated pests. The use of selective or targeted sampling may limit the opportunities to derive information about the overall pest status of the lot or consignment, because sampling is focused on where specific regulated pests are likely to be found not on the remainder of the lot or consignment. (ISPM 31, 2016)
The means of introduction and potential establishment are called ‘pathways’, defined as ”any means that allows the entry or spread of a pest” (FAO, 2002). Examples of human-mediated pathways include cargo, passengers, and conveyances entering a country or place where no such pests exist. To help minimize the threat, cargo, passengers, and conveyances are inspected at ports of most countries by officers of Plant Health Inspection Services or Plant Quarantine officers in their respective countries. Despite the best efforts of Plant Quarantine Division of Ghana, non-indigenous species continue to be introduced into the country and to become established.
There are several pathways (vectors) through which invasive species can be introduced. Introduction of invasive species can be through production of crops, transport of goods, tourism activities and movement of people. Of these pathways, the major one is through foreign trade of goods and services.
Apart from the biological characteristics of invasive organisms, many other factors need to be considered during the implementation of quarantine measures. In particular, are the pathways via which organisms can enter new areas. There are three broad categories of pathways of introduction:
1. Species that spread naturally either passively by water or wind, including extreme events such as cyclones, or actively flying, crawling, or swimming.
2. Species that are accidentally introduced hitch-hiking or vectored on/by something for example: during trade; movement of material during emergency relief or conflicts; traditional movement of people; movement of plants, animals, or soil; scientific materials; traveler’s personal effects; movement of contaminated agricultural, military, or industrial equipment; ships, including ballast water.
3. Species that are deliberately introduced, e.g. new genetic stock, biological control, hunting, pets, or ornamental trade. These may be introduced legally or illegally (smuggled) into an area. A further layer of complexity arises when one community considers an organism invasive and another community (often in the same country) considers the species beneficial.
In the literature, the risk of introduction of invasive species is usually analyzed within the context of two influencing forces: economic activities that create risk and economic activities that reduce risk. Increased trade flows of goods and services among countries can increase the risk of invasive species introduction.
2.9 Common Insect Pests Associated with EU Banned Agricultural Commodities
Fruits production is one of the fastest growing sectors of the horticulture industry in Africa (Weinberger and Lumpkin, 2007). The sector contributes to poverty alleviation by promoting food security while helping to increase total export earnings for African countries. Throughout Africa, several fruit crops are grown for both domestic and export markets. The major ones include mango, citrus, papaya, avocado, banana, and the cucurbits. In 2007, the horticulture industry generated over $16 billion in foreign exchange from exported commodities and over $6,500 million domestically to the continent; directly and indirectly employing over 40 million people (World Bank, 2008). More than 50% of the production volume is affected by fruit fly infestation. Currently, the key pest constraint for the increased and sustainable production of fruit crops in Africa is infestation by the fruit flies (Jaeger, 2008). There is therefore, need to guide against threats from invasive pest which causes more damage once they are established in any place.
There has been continuous and increasing number of interceptions by European Union (EU) Member States. The most commonly intercepted organisms include non-European Tephritidae (fruit flies), Thrips palmi and other Thysanoptera (thrips), White flies, Bemisia tabaci, both IAS and egg-plant borer, Leucinodes orbonalis. In addition, between 2008 and 2010 there were 24 notifications of interception of citrus blackspot (Guignardia citricarpa) (Europhyt, 2014). These harmful organisms were found mainly on exported vegetables and fruits of mango (Mangifera indica), garden eggs (Solanum aethiopicum), aubergine and/or ravaya and other aubergine vegetables types (Solanum melongena), peppers (Capsicum frutenscens), karela (Momordica sp.) and citrus from Ghana.
A survey was carried out to collect specimens for taxonomic studies, to study the population biology of an insect species and to find out what kinds of insects occur in a particular area or biodiversity. The surveys became more and more important since, based on the results of the survey, management strategies are developed and applied for the conservation of biological diversity in a certain area. Furthermore, the findings of a survey can be used for the preparation of environmental plans and environmental impact assessments in general.
3.1 Research Design
Specific Pest Surveys (SPS) design was developed and used for this research. It is a combination of simple random sampling methodology and targeted sampling methodology. The former eliminates the bias of the latter sampling methodology. The SPS is a deliberate strategy of a research design that also involves a combination of observations and experimentation and using high illuminated lights in order to force out these insect pests that are often hidden in the imported agricultural commodities. The design was used to intercept insect pests entering the country through the Aflao Land border (Land Port), Kotoka International Airport (Airport) and Tema Harbour (Sea Port) pathways. The purpose of adopting this SPS design was to confirm the possible entry and presence of any insect pests found on imported agricultural commodities through the three pathways mentioned above in the southern sector of Ghana.
3.2 Area of Study
The study was carried out in the Southern part of Ghana at three major entry points, namely: Kotoka International Airport (KIA) in Accra, Tema Harbour in Tema and Aflao border in the Volta Region. The three entry points or areas which were selected, were based on their location and stature as the major entry points of imported agricultural commodities in the southern part of Ghana for the country as a whole. They were also selected based on the limited resources the researcher had.
Stations Scheduled days Time periods
Aflao Border (Land port) Sundays 4:00pm – 10:00pm
KIA (Airport) Wednesdays 7:00pm and 1:00am
Tema Harbour (Seaport) Mondays through Saturdays 8:00am to 5:00pm
Table 3 Location and Time schedules of various data collection points
Based on field survey
3.3 Targeted and Sampling Procedure
The survey was designed to favour detection of insect pests. However, random sampling was used in the research. The selection of the consignments for data collection was done using simple random sampling approach. This approach was chosen mainly to take care of the bias earlier mentioned. The agricultural commodities were then closely observed under high laminated lights which help in both enhancing the sight and teasing the insect pests to come out of their hideouts. There were seven study visits to each of the three data points lasting for six months from November 4th, 2015 to 4th May, 2016.
3.4 Survey Procedure
The selection of survey procedures was determined by the type of sign or symptom by which the insect pests were recognized, and by the accuracy or sensitivity of techniques used to test for the type and nature of the insect pest. The survey procedure was timed majorly in relation to the arrival of the conveyances bringing the various imported agricultural commodities into the country. For Aflao the commodities arrive mostly in trucks every Wednesday and Sunday evenings between the hours of 4:00pm and 10:00pm. The researcher chose Sundays for data collection at Aflao land port (border). This is because Wednesday was conflicting on the arrival of imported agricultural cargo at the KIA – airport in the evening. At KIA the cargoes mostly arrived on Wednesday and Thursday evenings between the hours of 7:00pm and 1:00 am midnight. At Tema this was monitored through the ships manifest as to the type of cargo being brought in, and the times were normally between the hours of 8:00am to 5:00pm during the day throughout the week including Saturdays. (Mondays to Saturdays).
Table 4 Number of visits to the entry points
No. Entry Point No. of visits Duration
1 Aflao 31
2 Tema 41
3 KIA 38
Total 110 6 Months
3.4.1 Market Survey
Four enclosed markets in Accra namely; Palace Shopping Mall, Koala Shopping Centre, Game shopping Discount and Marina Mall. These malls were chosen because they accepted and allowed for the survey to be undertaken on their retail exotic imported fruits and vegetables.
Samples of fruits and vegetables and other suspected potential articles that might harbour pests were taken for further examination. The samples taken were sent to the KIA Plant Quarantine Inspection Laboratory for examination.
• Detection and enumeration of all life stages (nymphs, eggs and adults) of insects were a priority. Since this is an efficient method for use in commercial, residential and specific area settings. Although this method is time consuming, substantial costs is also associated with time and labour, it provides only a snap shot in time if looking only for insects.
3.5 Data Collection Validity and Reliability of Data Gathered
The collection of data for this study was primarily done through a field survey aided with a laboratory testing centre, the Plant Protection and Regulatory Services Directorate; Plant Quarantine Laboratory at The Kotoka International Airport. A further end user market survey was conducted to either validate the primary data or otherwise. Both data was collected based on a designed field chart.
In order to ensure that data collected is valid for the research, the study adopted a double instrumental approach of first using close observation methodology and then with experimentation method to confirm and monitor any identified insect pests for a period of time the data was collected. By experimentation, any observed trace of an insect pest is tracked from the egg to the young adult fly stage in order to ensure that real identity of the insect pest is confirmed. This approach served as a triangulated procedure that guaranteed the validity and reliability of the data collected.
3.6 Data Analysis
Analysis is a generic term that adopts three basic categories in breaking down data: description, analysis and interpretation. The procedures for analysing data involved the presentation of the data gathered from the field observation and conducted experiment results.
Data collected was analyzed in two forms. First, the descriptive statistical methods was used to analyze the qualitative aspects of the data using SPSS software. This included bar graphs and path analysis diagrams.