Med Fruit Fly Invasion - Assignment Example

Med Fruit Fly invasion s name ABSTRACT The Mediterranean fruit fly (Medfly) is one of the most common, invasive and detrimental pests that exists in almost all regions of the world. At present New Zealand remains free from infestations of pests such as the Medfly. Nevertheless, the Medfly is a potential threat to the economy of New Zealand. The Medfly is extremely adaptable and therefore has been successful in invading and infesting many regions around the world. The fly is capable of establishing its population very rapidly under suitable conditions and therefore needs to be tackled effectively. Most countries which have been infested have had both successful and unsuccessful eradication programs. New Zealand too has a Biosecurity system which renders protection against such invasions and has been so far successful in keeping the country free from these pests. The main aim of this paper is to understand what the Biosecurity system and policies of the country are effective at during incursion responses and suggest ways in which such responses can be strengthened to ensure better protection against bioinvasions of the Mediterranean fruit flies. Introduction-Fruit Fly There are various kinds of fruit flies found in different regions of the world. The ones belonging to family Tephritidae are considered the true fruit flies. The most important members of the family are the Bactrocera sp and the Ceratitis sp. The Mediterranean fruit fly is binomially known as Ceratitis capitata and ranks among the top most destructive agricultural pests. Its origins lie in tropical Africa but today it is found around the world and is not only highly destructive but is highly invasive as well (Huang et al,2009,p1239). Characteristics/adaptations The med fruit fly can be easily distinguished from any other fruit flies because of its characteristics. An adult fly is slightly smaller when compared to an adult common housefly. An adult fly measures about 3-5 mm. The body is straw yellow in color with brownish tinge. The thorax is off-white in color. It bears some marks on the wings but the most prominent one the presence of a broad yellow band across the middle portion of the wings. It also has ocellar bristles (bristles present on the dorsal part of the head) and its eyes are purplish in color. The adult male flies can be segregated from the female flies because the presence of a long pointed expansion on the top of the orbital setae (present between ocelli and eyes) (IFAS,2010). Figure 1: Showing position of the Orbital setae and ocellar bristles Life history The life history activity of Medfly is dependent on temperature and it completes its life cycle under optimum conditions of temperature. The duration of each stage and the overall survival of the egg, larva or the pupa depends on the temperature since it prefers Tropical climatic conditions (Ricalde, 2012). It is capable of going through all the 4 stages and completing its lifecycle within a short period of 21 days if the conditions are favorable. They female flies lay their eggs, generally 14-15 in number, inside intact fruits with the help of their sharp ovipositors. An average female fly is capable of laying almost 800 eggs in her lifetime. Female do not oviposit at very low temperatures. The eggs need slightly warm temperatures to hatch and under such conditions they hatch within 2-4 days. The larval stage is comprised of three instar stages and the duration of these immature stages ranges between 14- 63 days in total, at a temperature of about 30-15 degrees (Duyck & Quilici, 2002, p 461). The larval stage usually lasts between 7-10 days. However the length of the larva as well the time required for the growth of the larva depends on the type of fruit the eggs are laid in. Once the larva is mature it pupates in soil. The pupal stage lasts for about two weeks after which the adult flies emerge. Reproductive potential, The newly emerged adults are not sexually mature and the adults need about 4 days to become sexually mature. The reproductive potential of female flies decreases with age. Therefore reproductive potential is inversely related to mortality (Muller et al, 2001, p445).This means the number of eggs produced by the female fly depends directly on the total length of time she survives for. Ecological function The Med fruit fly is extremely important economically. It is capable of destroying fruits and vegetables in large numbers. Fruit trees are primarily most affected since the female lays eggs in the fruits. Normally the flies are not capable of flying large distances yet they are found in different parts of the world today. Much of this spread is attributed to human movement and trade. If export of fruits or other products is done from a country which is infested with the fruit fly there is a chance that the exported products may contain eggs or larva of the flies. This leads to introduction of the pest into the new country. Humans too act as vectors since they travel from one part of the world to another and may carry eggs, larva or pupa with them. Ecological niche The Medfly is extremely adaptable and can survive in different conditions. This is perhaps the key to its successful establishment in different parts of the world. However it has been seen that the ecological niche of C.capitata is almost similar to that of C.rosa (Natal fruit fly) and therefore both are capable of infesting different regions of the world (Meyer et al,2007,p270). It has been seen that dry and hot climatic conditions such as that of Western Africa are not preferred by the flies. Tropical and sub-tropical regions and temperatures are the best conditions for the flies which lead most of their lives inside fruits and on leaves of tropical trees. Host plants and fruit trees include plums, kiwi, peach, olive, tomato, mandarin orange, avocado etc to name a few. It needs to be understood that the fly is capable of infesting over 200 different kinds of trees. Implications for New Zealand of an invasion of this pest The Mediterranean fruit fly is a major threat to the horticultural and agricultural industries of New Zealand. Fruits and vegetables form a major part of New Zealand’s export products and are close to a 3.5billion dollar industry. Therefore bioinvasions by fruit flies is bound to have negative impacts on the economy of the country. The best way to understand the implication of invasion on New Zealand’s economy would be to study the Medfly incursion case of 1996, Auckland. Following the incursion, exports from Auckland were absolutely restricted for about 18-20 months, even after total eradication leading to huge losses (Underwood, 2007). One of the most important fruit exports that may be affected by such incursion is the kiwifruit industry. New Zealand is the prime exporter of kiwis and it is estimated that if incursion does occur the kiwi industry would have to withstand losses of about $57 million (Kiwi Fruit Vine Health, 2014). This is because once an outbreak is detected most countries which form the premium markets and which import the products refuse to accept fruits and vegetables from the country which has been invaded leading to huge losses. The avocado industry of New Zealand would also suffer since the avocados from New Zealand would not be accepted by Australia which is the prime importer of avocado fruits. However New Zealand is not the sole country suffering from such infestations. The Medfly has spread to almost all parts of the world negatively affecting the fruit and vegetable products. One of the biggest invasions of the Medfly was recorded in California, USA. The fly was detected from 1986-1991 and almost 10 eradication programs were launched to eradicate the population of the flies since the population of flies had become well established in the almost 13 counties of California (Carey,1992).The total cost was close to $150 million. The invasion not only affects the economy on the basis of damaged crops or fruits and costs involved in incursion response but also affects the local economy of the growers and small-scale horticulturists. This primarily happens because local farmers or horticulturists who fall within the areas where the fly is detected have to suffer losses due to vegetation or fruit loss since these areas are treated to extensive eradication procedures such as fumigation and spraying of insecticides. Florida has been invaded by the pest twice in the past. The citrus industry has been the most affected one in Florida. It was 1929 that Florida was first invaded by the pests. Measures such as bait spraying and fruit stripping were done to control the population of the fruit flies. It took almost 2 years and $7 million to eradicate the flies. Australia, especially the Western part of Australia too has been invaded by the pest and has been successful in establishing its population. Insecticides are used before and after harvest as a measure to protect the crops against infestation. Common insecticides that are used include fenthion-based ones. These protective measures cost the state $10 million on an annual basis (Cook et al, 2013, p 2). However, owing to introduction of policies against usage of certain insecticides this cost would be increased thereby affecting the overall cost of production of fruits and vegetables. Invasion biology Bioinvasion of the Medfly in the past has been very impressive. Most of these invasions are being attributed to the global warming phenomenon since the gradual rise in temperature helps the flies acclimatize to newer environments and stabilize their population. There is no concrete evidence to pinpoint the exact origin of the flies; most researchers believe that the flies originated in the Sub-Saharan region of Africa (Diamantidis, 2011).Today, even though New Zealand is free from the pest, many other countries are known to be infested by it. The Medfly has become an ideal species for various Bioinvasion studies because of its wide distribution, role in economics and well-documented bioinvasions (Diamantidis, 2011). Countries with well established infestations include: North and South America- Brazil, Argentina, Columbia, USA. Asia- Jordan, Cyprus, Israel, Turkey, Yemen. Africa- Morocco, Nigeria, Algeria, Angola, Kenya, Libya, Zimbabwe. However these are just a few names from a vast list of countries infested with Medfly but the widespread distribution of the fly establishes the fact that the fly can easily adapt to different conditions and establish its population. Details of the incursion response The most important part of New Zealand’s Biosecurity system is the constant vigilance for fruit fly detection. The Ministry of Primary Industries (MPI) which spearheads the MAF Biosecurity programme has been so far successful in keeping New Zealand a fruit fly-free country. The main aim of the MPI concerning Biosecurity is to protect the environment of the country against harmful invasions and initiate immediate incursion responses (MPI,2014). One of the earliest instances of Medfly invasion in New Zealand was in 1996. In the month of May,1996, two male Med flies were captured in the traps set in Auckland. Following the detection of the presence of fruit flies MAF initiated an immediate incursion response to the invasion. The first step was to set up more traps. Therefore, more traps were set up in the region to detect and capture female flies. During trapping, female flies and larvae of the Medfly were seen thereby making it clear that the fly had succeeded in establishing its population in New Zealand. However, with an extensive control programme that cost the MPI almost $5 million the fruit fly was successfully eradicated by 25th may of the same year (Gilbertson, 2012). Natural dispersal of C.capitata naturally is not known to exceed 10 km therefore immediately steps were taken to contain the population within a certain boundary (Karsten et al, 2013). Following this MAF established three different zones of exclusion around the initial area where the males were found. The three zones were Zone A (200 meters radius), Zone B (1.5 kilometers radius) and Zone 3 (15 kilometer radius). These three exclusion zones were thoroughly monitored, more traps were set, fruit movement from these areas were stalled and the areas were treated for total eradication of pupa or larva from the soil or the fruits using insecticides while adults were lured by baits and then killed. We could therefore see usage of three responses that were used to detect and control the invasion of the fruit fly. Traps were used for detection while insecticides and baits were used for the eradication program. The MAF surveillance program is responsible for yearlong keen surveillance of the presence of any kinds of pests. The traps commonly used in the programme are the Lynfield traps which also the trap used in the 1996 incursion response. The Lynfield traps contain a chemical based lure such as Methyl Eugenol which attracts the male flies to the traps. The traps also contain a strip dipped in a strong insecticide. These traps are set up in prime places such as tourist centers, areas of horticultural importance, populated places and trade related areas since these areas mostly serve as the first invaded regions of infestations. Once population had been detected, an eradication programme had to be initiated. This was done by increasing the number of traps to make sure that most adult members of the population are trapped and killed. The adult males were trapped with help of baiting using Bait sprays. In this case bait which is a mixture of protein and carbohydrate is mixed thoroughly with effective insecticides. These mixtures are put were put on the plants that the fruit flies normally feed upon leading to death when the flies fed on this bait-added food. Therefore even females were caught using the baiting technique. However, it was not sufficient to just rely on catching the adults since to render protection against infestation the larva and the pupa was also required to be killed. For this, insecticides were sprayed in the fields around the region where the fruit flies were first detected. Following the 1996 Medfly outbreak, baggage scanners had to be installed at international airports to detect larvae or adult flies (Stephenson et al,2003, p5). Critique of the incursion response New Zealand’s incursion response has always been rapid and thorough. During the bioinvasion of Medfly in 1996 immediate steps were taken and I personally feel that the response was early enough to be tackled with ease. However I believe that the response approach can be modified for better results i.e. usage of better and modern technology to combat invasions effectively. So far, New Zealand has remained pest-free however, no large scale infestation has been seen or no population had succeeded in establishing over a large area, thereby the measures adopted by the MAF program was so far sufficient for eradicating the pests. MAF adopts the usage of Lynfield traps using sex attractant lures as the basic protective or surveillance measure against the Mediterranean fruit fly. This is perhaps the best method to monitor the presence of any pest fruit fly population since Mediterranean fruit flies are known to respond quite well to lure based traps. Lynfield traps were also used during the late 90’s for fly detection and were the best suitable method as well. The outcome of these traps yielded desired results since it helped in early detection of flies that already invaded the area. I feel this early detection could have been made much more efficient if early detecting systems such as baggage and luggage scanners were adopted to help in detection of flies coming into the country. However, the incursion response of 1996 did have its own pitfalls and was not very environment-friendly either. The adult male and female populations were baited using bait and insecticides however there were chances that the adult population would move from a bait-applied tree to other trees thereby leading to failure of the bait trapping. The chances of such instances could have been reduced with the help of modern technologies. The MAF program needs to adopt better technologies to ensure that the chances of survival of the males and females are reduced drastically thereby helping in the eradication drive. In California, which was infested with the Medfly, eradication has been achieved using genetically modified temperature sensitive lethal flies (tsl mutant flies) in the control program that relied highly on sterile sex approaches (Calla et al,2014). The surveillance and protection against pest flies of California use biological controls such as sterile flies which when mated to a female do not produce any fertile eggs thereby leading to rapid decrease and subsequent extinction of the pest fly population. In the California protection program such sterile flies are reared and are released on a regular basis to keep the fly population under control. However the MAF, New Zealand does not have such programs and uses traps instead for detection. In case fruit flies are present in areas where traps are not set it would not be detected at all. However of the sterile fly technique is adopted it would lead to automatic control of fruit fly population in case it is established. The detection system of the MAF program is mostly based on chance and therefore much depends on the efficiency of the traps and in this case Lynfield traps are primarily used for such detections. Therefore, the detection of the male flies in 1996 was much on chance which means that there were chances of non-detection as well. I feel this risk maybe reduced by uadoption of better equipments. There exist better traps such as the C&C trap which is based on sticky paneling. The trap is made up of a metal hook and a plastic container which has three panels. The middle panel is filled with chemical lure which is released slowly and acts as a sex attractant. The other panels are sticky and help in capturing male flies which are lured by the chemical released from the central panel. The traps are even brightly colored and research studies in California and Guatemala have proved that the C&C traps perform much better than Lynfield or McPhail traps (Mangan & Cunningham,1996). MAF may also seek the help of biological control such as natural enemies of the fruit flies that feeds on them thereby helping in eradication of the population. During the incursion response in 1996 the bait trapping used for baiting the adult population and killing them made use of bait mixtures that contained harmful insecticides such as malathion which was applied aerially. The outcome of this was not desired since it was harmful for the environment. The areas around the incursion response were treated with malathion exposing the surrounding population of humans, insects and other forms of life to a pesticide. There exist better forms of such bait sprays which are believed to be equal to malathion. Researchers have already developed phyloxine B also known as red dye number 28. This chemical is much safer for the environment when compared to malathion based insecticides. Field evaluation has also shown that this chemical was more effective than malathion-based sprays and was more toxic to Medfly (Moreno et al, 2001, p 1419). Moreover, Phyloxine-B is effective at both the larval and the adult stages since it harms the longitudinal muscles of the larva and abdominal muscles of adults thereby causing malformation and resulting in death (Berni et al, 2003, p662). The MAF program needs to adopt such equally effective but less harmful chemicals in place of what was used in its previous incursion response. In addition to this, there has been detection of malathion- resistant Medfly which means that extensive use of insecticide may induce mutation the fly genome leading to resistance and therefore it is important to sue only effective and environment-friendly chemicals to get rid of them (Ortego et al,2010,p39). The response however restricted movement of fruits from the area which even though lead to economic losses was a good decision made by MAF because it helped contain accidental spreading of fly larva and assisted in pest management by restricting the pest within a given geographical boundary. I feel that the country’s response to Medfly invasion in 1996 was good since it included early detection. The final outcome was desirable in terms of pest management however, the response was not environment friendly and in the future less harmful chemicals need to be adopted. The methods and strategies used for fly management were not good enough even though the results were good however in case the fly population was larger these methods might have yielded same results and therefore more effective measures such as better traps, early detectors, environment friendly chemicals etc need to be used. Therefore, the incursion response that had been initiated did succeed in keeping the region pest free by launching eradication approaches however, in the future the program needs to be upgraded using better, more effective and safer techniques for detection and eradication of the pest fly population in New Zealand. Conclusion Biosecurity of a country is an extremely important section of protection since the economy is heavily dependent on it especially in the case of New Zealand. The incursion responses of New Zealand against pest flies have been successful no doubt but there exists several loopholes which could have led to further infestations and widespread establishment of Medfly population. The MAF program is very much vigilant; however, it needs to adopt novel technologies and newer and safer methods to ensure more effective surveillance and detection. Therefore replacement of Lynfield traps with better C&C traps, usage of Phyloxine-B or biological controls needs to be incorporated in the incursion strategies as well. The Biosecurity system of the country needs to be upgraded following leads from that of other countries to ensure faster eradication success with minimal economic losses. REFERENCES Berni,J. et al (2003). Phloxine B effect on immature stages of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae) (Wiedemann). Journal of Economic entomology, 96(3),662-668. Calla,B. et al. (2014). A genomic perspective to assessing quality of mass-reared SIT flies used in Mediterranean fruit fly (Ceratitis capitata) eradication in California. BMC Genomics,15(98). http://www.biomedcentral.com/1471-2164/15/98 Carey,J.(1992). The Mediterranean fruit fly in California: taking stock.California Agriculture,46(1),12-17. http://californiaagriculture.ucanr.edu/landingpage.cfm?article=ca.v046n01p12&fulltext=yes Cook,D.C. et al. 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Its our Place to protect. http://www.biosecurity.govt.nz/ Morenos,D.S. et al. (2001). Field evaluation of a phototoxic dye, phloxine B, against three species of fruit flies (Diptera: Tephritidae). Journal of Economic Entomology, 94(6), 1419-1427. Muller,H.G. et al (2001). Reproductive potential predicts longevity of female Mediterranean fruitflies. Proceedings of the Royal Society of the Biological Sciences.268(1466),445-450. Ortego,F. (2010). INSECTICIDE RESISTANCE IN FRUIT FLIES: THE CASE OF MALATHIONRESISTANCE IN SPANISH POPULATIONS OF CERATITIS CAPITATA. 8th International Symposium on Fruit Flies of Economic Importance. Valencia, 39-40. http://riunet.upv.es/bitstream/handle/10251/11200/2367_libro_e%5B1%5D.pdf Ricalde,M.P.(2012). Temperature-dependent development and survival of Brazilian populations of the Mediterranean fruit fly, Ceratitis capitata, from tropical, subtropical and temperate regions. Journal of Insect science,12(33). Stephenson,B.P. (2003). BIOSECURITY APPROACHES TO SURVEILLANCE AND RESPONSE FOR NEW PLANT PEST SPECIES. New Zealand Plant protection, 56, 5-9. http://www.nzpps.org/journal/56/nzpp_560050.pdf Underwood,R. (2007). Fruit Fly: Likely Impact of an incursion of fruit fly in the Bay of Plenty, Hawkes Bay or Nelson. Fruition Horticulture. http://www.fruition.net.nz/_fruition/Library/Article/Fruit%20Fly%20Final%20Report%202007.pdf Figure reference: Fig 1: Orbital Setae. Delta. http://delta-intkey.com/anatox/l/media/html/_c007.htm Read More