Proceedings of 6th International Fruit Fly Symposium 6–10 May 2002, Stellenbosch, South Africa pp. 127–130

The SIT control programme against Medfly on Island

L. Dantas*, R. Pereira, N. Silva, A. Rodrigues & R. Costa Programa Madeira-Med, Estrada Eng. Abel Vieira,262, 9135-260 Camacha, Madeira,

On Madeira, the Mediterranean fruit fly, Ceratitis capitata (Wied.) (Medfly), causes more than 2.5 million in losses each year and is the single most important factor limiting expansion of fruit production. In 1996 the government of Madeira supported by the European Union (EU) and the International Atomic Energy Agency (IAEA) initiated a sterile insect technique (SIT) programme to control the pest. An important consideration is that SIT, being an ecologically compatible tech- nique, does not cause conflicts with the economically important tourist industry of Madeira. Current production from the Madeira-Med Medfly factory averages 40 million fruit flies per week, with weekly releases of sterile males averaging 30 million per week.A genetic sexing strain is used so that few female Medflies are released. The Madeira Medfly programme was one of the first to use SIT for fruit fly control as opposed to eradication. The objective of this programme is to reduce Medfly fruit infestation levels to below 2% in 10 specified edible fruit species. In this paper we present results from 1997 to 2001,with emphasis on the north coast of Madeira and Islands.

INTRODUCTION limiting factor for increased fruit production on Madeira – facts and figures the island. Farmers routinely apply insecticides to The Mediterranean fruit fly, Ceratitis capitata control Medfly but the results have not been satis- (Wied.) (Medfly), is a major pest of fruit in the factory, and the insecticide treatments cause an Portuguese Autonomous Region of Madeira where unknown amount of environmental damage. it attacks more than 40 species of fruit (Vieira 1952). Medfly has been present on Madeira for a long This region is located 980 km WSW from mainland time, and rural residents and producers of fruit are Portugal (32°N and 17°W). well aware that it is a serious pest. However, the Madeira has two populated islands. Porto Santo majority of the population on Madeira are in urban is small (about 50 km2) with topographic and areas and are unaware of the damage caused by temperature conditions favourable to Medfly. Medfly. However, poor soil and low precipitation (380 mm/year) do not permit an abundance of host THE SIT PROGRAMME fruits. Mass production of sterile Medflies 2 The main island, Madeira (740 km ), is volcanic To implement the Madeira-Med Programme it with very little level land suitable for large agricul- was necessary to build a factory to produce 50 tural production.The north coast is cooler than the million pupae per week (Pereira et al. 1996). This south (air temperature at sea level in the north estimate of production capacity was based on corresponds to air temperature at 300 m elevation other Medfly SIT programmes using genetic sex- inthesouth)andthemaximumelevationis1881m. ing strains (Hendrichs et al. 1995), knowledge of The small island of Porto Santo has very few hosts Medfly biology, and data collected during several (except for fig and Opuntia), few people and is years of adult and larval surveys on Madeira. The essentially a desert with the maximum elevation strain in production is ‘Vienna 7 mix 2000’.Of the being 517 m. 40 million per week pupal production, 30 million The climate of Madeira Island, particularly below (males) are sterilized for release in the field and 600 m elevation,is favourable for the development the remaining 10 million (both sexes) are used to of high populations of Medfly. Conditions in maintain Medfly production. Pupae are sterilized , the capital city, and in low altitude areas with a minimum dose of 100 Gy from a cobalt 60 are very favourable for Medfly throughout the radiation source (Gammacell 220, Nordion®). year. Eight generations per year of C. capitata are The overall strategy for Medfly control on Madeira produced in the Funchal area (Vieira 1952). is to release sterile males in areas of the island Medfly causes economic damage estimated at where Medflies overwinter and thus where the about C2.5 million per year in both commercial pest is active year-round (Pereira et al. 2000). This and backyard fruit production, and is the primary means that half of Madeira Island and the

*To whom correspondence should be addressed. whole of required treatment. E-mail: [email protected] Until now the greatest effort has been concen- 128 Proceedings of the 6th International Fruit Fly Symposium trated in the north of Madeira Island and on Porto female Medflies but also sufficient males to use for Santo Island, places were the winter is cooler and estimates of sterile male distribution.We started in the wild fruit fly population is lower. 1999 with 108 Tephri traps (100 on Madeira and eight on Porto Santo Island) baited with the Sterile fly handling and releases three-componentlure to estimate wild populations Sterilized pupae are placed in PARC boxes for and to evaluate sterile male releases. adult emergence. Sugar and water are supplied in Thetrapswereplacedinthemostprevalenthosts an agar block on top of each box. After emer- at the selected location (one per 4 km2) in the sterile gence, flies are prepared for aerial dispersal using fly release areas. These Tephri traps were moved the chilled-fly system developed by the U.S. Depart- frequently inside the 4 km2 blocks, were checked ment of Agriculture, allowing the flies to be main- weekly for catches, and the attractant changed tained at 4°C until release. every two months. Madeira-Med uses aerial dispersal because it is Data collected on the number of females and more efficient, more effective and cheaper than males captured, and sterile male distribution, are ground release. Ground releases are only used in a continually used to guide the control programme. few locations where aerial release is not safe.Since Surveys of the larval infestation in various fruit 1998, sterile male flies have been dispersed by a species were started in 1995 to evaluate the level twin-engine aircraft, twice per week over all parts of infestation in different hosts at different alti- of the island included in the SIT programme. The tudes. Initially (until 1998), the purpose of fruit density of flies dispersed varies between 50 000 sampling was to determine the Medfly host list, as and 125 000 per km2 per week, depending on wild well as levels of infestation (numbers of larvae per fly infestation. kg of host, and larvae per fruit). These data were The sterile Medflies were dispersed on pre- necessary to define the areas and densities of determined flight paths, altitudes and frequency. releases. After 1999, fruit sampling was carried out Flight paths and wind information are analysed to evaluate the percentage of infestation in key to gain better understanding of the reasons for hosts and to evaluate the success of the SIT different sterile fly/wild fly results in the trap programme. gridline. This was initiated after the Madeira-Med programme defined the success as less than 2% Field surveys fruit infestation in 10 specified fruit species (listed Surveys of Medfly larval infestation, wild adults in Fig. 1). and sterile adults,host species and phenology,and temperature were continuously made, and the RESULTS AND DISCUSSION data were used to guide the control programme. From 1994 to 1997 a study to measure Medfly Effect of elevation on Medfly populations populations at different altitudes was carried out On Madeira, Medfly populations were higher in using 340 Jackson traps.Two sites (replicates),each the south than in the north because of warmer at four elevations (0–200 m;200–400 m; 400–600 m weather and a wider number of hosts in the south. and 600–800 m) on both the north and south Fly captures also decreased as elevation increased, coasts plus Porto Santo were included in the study. mainly because of cooler temperatures.During the Each replicate consisted of 20 Jackson traps, 10 winter months, populations were present up to baited with trimedlure and 10 with hydrolysed 400 m above sea level in the south and up to 200 m protein (Pereira & Carvalho 1996). The traps were above sea level in the north. In March and April placed in the most prevalent hosts at the selected the pest was found only below 400 m in the north location and remained in these hosts throughout and 600 m in the south. From May to October the study. The Jackson traps were serviced bi- Medfly populations existed at all altitudes under weekly. The protein bait was replaced at each visit study bellow 800 m. and the trimedlure every two months. With the recent development of female attractants Size of Medfly populations for Medflies (a lure comprising ammonium acetate, On Porto Santo Medfly populations remained trimethylamine and putrescine) another tool was low but constant during the first 4–5 months of the made available for Medfly population surveys year. During April/May populations increased (Epsky et al. 1999). The so-called three-component mainly as a result of ripening pears, and in August lure is a food attractant that attracts primarily the population was higher because of the greater Dantas et al.: SIT control programme against Medfly on Madeira Island 129

Fig. 1. Percentage of infested fruit on Porto Santo and Madeira (north coast) Islands at the end of the study period in 2001. availability of figs and Opuntia. Sterile Medfly production and release Before the beginning of sterile releases, 226 393 During 2001,1031 million pupae were produced. wild Medflies were caught in Jackson traps in 1995, From these, 753 million sterilized male flies were 189 249 in 1996 and 275 061 in 1997.After the start released on Madeira and Porto Santo Islands of releases, and using the three-component lure (Fig. 3);700 million flies were released by air and 53 it was possible to evaluate the effectiveness of the million by ground. In 2001, due to problems with SIT programme in reducing the Medfly popula- the quality control of sterile flies it was necessary to tion on Madeira to a level where fruit infestation is change the Medfly genetic sexing strain in the below 2% in 10 specified fruit species (Figs 1 & 2). factory from ‘Vienna 7 mix 99’ to ‘Vienna 7 mix

Fig. 2. Captures of wild females in flies per trap per day (FTD) in 108 Tephri traps baited with three-component lure from 1999 to 2001. 130 Proceedings of the 6th International Fruit Fly Symposium

Fig. 3. Number of sterile male Medflies released on Madeira and Porto Santo Islands per year.

2000’. The replacement activity resulted in a Regiões Ultraperiféricas Portuguesas), and the decrease in Medfly production with a consequent International Atomic Energy Agency. reduction in numbers of sterile flies released during the critical period of early 2001. REFERENCES EPSKY, N.D., HENDRICHS, J., KATSOYANNOS, B.I., VÁS- Effectiveness of 2001 SIT programme QUEZ, L.A., ROS, J.P., ZUMREOGLU, A., PEREIRA, R., BAKRI, A. & HEATH, R.R. 1999. Field evaluation of fe- As a result of the low numbers of sterile flies male-targeted trapping systems for Ceratitis capitata released during 2001, larval infestation increased (Diptera: Tephritidae) in six countries. Journal of Eco- and no effective control of the wild Medfly popula- nomic Entomology 92: 156–164. tion was achieved during the year. HENDRICHS, J., FRANZ, G. & RENDON, P. 1995. Increased The presence of large Medfly populations in urban effectiveness and applicability of the sterile insect technique through male-only releases for control of areas makes fruit fly control with SIT particularly Mediterranean fruit flies during fruit seasons. Journal difficult on Madeira. Madeira is densely populated of Applied Entomology 119: 371–377. at the lower elevations,which is the zone of highest PEREIRA, R. & CARVALHO, J.P. 1996. Trap utilisation on Medfly population. Most people live in separate study of Mediterranean fruit fly populations at citrus houses with a number of Medfly host plants in groves in Portugal. In: McPheron, B. & Steck, G. (Eds) their gardens. In order for an SIT programme to be Fruit Fly Pests, a World Assessment of their Biology and Management. 135–140. St Lucie Press, Delray Beach, successful and economical on Madeira, wild Florida. Medfly populations in these urban areas will have PEREIRA, R., BARBOSA, A.M., BRAZÃO, A., CARVALHO, J.P. to be reduced to low levels so that there is a favour- & LINDQUIST, D. 1996. Area-wide control of the able sterile fly : wild fly ratio. How to achieve this Mediterranean fruit fly on Madeira with sterile insect wild fly population reduction has not yet been technique. Proceedings of the International Society of Citriculture: 568–572. resolved. PEREIRA, R., BARBOSA, A.M., SILVA, N., CALDEIRA, J., DANTAS, L. & PACHECO, J. 2000. Madeira-Med, a ACKNOWLEDGEMENTS sterile insect technique programme for control of the Madeira-Med is financially supported by the Mediterranean fruit fly in Madeira, Portugal. In: Tan, Regional Government of Madeira, the European K-H. (Ed.) Area-Wide Control of Fruit Flies and Other Union through POSEIMA (Programa de Opções Insect Pests. 433–438. Penerbit Universiti Sains Malaysia, Penang. Especificas para Fazer Face ao Afastamento e VIEIRA, R. 1952. A mosca da Fruta (Ceratitis capitata, Insularidade da Madeira e Açores), REGIS II Wied.) na Ilha da Madeira. Grémio dos Exportadores (Programa Operacional de Desenvolvimento das de Frutas da Ilha da Madeira.