ASSESSMENT OF FRUIT FLY BACTROCERA INVADENS (DIPTERA: TEPHRITIDAE) PRESENCE IN EASTERN PROVINCE OF RWANDA. M.Olivier & 2 Hance Thierry,

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1 ASSESSMENT OF FRUIT FLY BACTROCERA INVADENS (DIPTERA: TEPHRITIDAE) PRESENCE IN EASTERN PROVINCE OF RWANDA 1* Harelimana Anastase, 2 Le Goff Guillaume Jean, 3 Rukazambuga Daniel, 4 Ngamata M.Olivier & 2 Hance Thierry, 1 National Agriculture Export Development Board, P. O. Box 104 Kigali, Rwanda 2 Université catholique de Louvain, Earth and Life Institute, 1348, Louvain la Neuve, Belgique 3 National University of Rwanda, Faculty of Agriculture, P. O. Box 117 Huye, Rwanda Abstract 4 University of Lay Adventists of Kigali, P.O. Box 6392 Kigali * haranast@yahoo.fr Fruit flies are one of the world s most devastating crop pests, causing millions of Dollars in production loss each year. In Africa there are several species that attack fruits, vegetables and native hosts. Among these are two species that have recently invaded Africa: Bactrocera invadens and B. cucurbitae (Diptera: Tephritidae family). These two species attack a wide variety of crops including mango, guava and tomato. B. invadens, an invasive fruit fly from Asia, also infests citrus and cashew nuts. Since its first detection in Kenya in 2003, B. invadens has spread to 26 countries in Africa and is known to infest at least 31 host plants. Both B. invadens and B. cucurbitae are devastating pests that can have a severe impact on sustainable agriculture and rural livelihoods, as well as export markets. No serious fruit fly surveys had ever been undertaken in Rwanda and it was not known whether B. invadens occurred in that country, nor were there any inventories of Tephritidae available for Rwanda. Scouting and monitoring of fruit flies was carried out in Rwanda regions where fruits are more produced using artificial pheromones (Methyl Eugenol, Cue lure, Trimed lure and 3- Components lure) combined with Vapona strip tablet to kill insects. The main objectives were to survey for the presence of the invasive fruit fly species, Bactrocera invadens and to confirm the results of 2009 from United States Department of Agriculture/South Africa indicating that Bactrocera invadens is present in Rwanda. The results from this work reveal that Bactrocera invadens and other fruit flies are already well established in Eastern Province of Rwanda on different kind of fruits. Yet, the fruit fly surveillance system should be extended to cover all fruit production areas throughout the territory of Rwanda for risk assessment and to determine which areas of Rwanda will be pest free for B. invadens. Training on fruit fly identification, control measures, and field management should be given to horticultural crops producing farmers as well as extension officers Keys words: Fruit fly, Para pheromones, Bactrocera invadens, Rwanda 1

2 INTRODUCTION In Rwanda, still 90 % of the rural population feed and lives thanks to agriculture (Gisaro, 2013). Farmers are still producing food crops mainly for their own consumption in a context of subsistence agriculture. A high priority is thus devoted to the development and promotion of horticultural products in Rwanda in order to diversify exportation and generate revenues to farmers. Presently, coffee, pyrethrum and tea are the main source of export revenues (Tardif-Douglin et al., 1993; MINECOFIN, 2002). According to Weinberger et al (2007), horticulture can offer opportunities for poverty reduction as it increases incomes and generates employments. The main problem that limits Rwandan farmers to develop horticulture is the insufficient production, lack of high yielding varieties, lack of storage infrastructure at farmer level and also the great loss caused by insect pests. The most serious pests of fruit in Eastern African countries are fruit flies of Tephritidae family (Ekesi et al.,2009). In 2009, Bactrocera.invadens was reported in Rwanda and in neighboring countries by UDSA/South Africa, (Cassidy, 2010), but the survey was not extended. Fruit flies of Tephritidae family are the main pests in fruit and vegetable production worldwide (Wih et al., 2012; Salum et al., 2013). For example, Bactrocera invadens (Fruit fly: Tephritidae) which is originated from Asia (Kimbogota et al., 2013) was first identified in Kenya in 2003, 2007 in Mozambique and then invaded many African countries: Burundi, Tanzania, Togo, Nigeria, and Malawi where this species is now responsible of great losses of fruit production (José et al., 2013). In, 2009, Bactrocera.invadens represented 90% of the total population in traps compared to other fruit fly species in Kenya (Ekesi et al., 2009). This species attack different vegetables and fruits including ripening banana (Cugala et al., 2012) and the loss caused by this fly is estimated between 30-80% in Kenya (José et al.,2013). Furthermore, coupled to its quarantine status, it has great negative impact on the economy of the country where is occurring (Benjamin et al., 2013). The loss caused by this fruit fly is increasing due to its easy dispersal through fruits transportation (COLEACP/PIP, 2007) and adult flights (Aluja et al., 2010). In 2009, a survey was conducted by USDA/South Africa in collaboration with Rwanda Agriculture Development Board. This survey was carried in Western Province, Southern, Northern Province and 2

3 revealed the presence of Bactrocera invadens in the monitored area. However, this survey did not cover the whole country. Due to this lack information on B. invadens in Rwanda, a first sampling was carried out in Eastern Province to see how the situation is in this area. This monitoring will help to get more information on the geographical distribution of this important pest, particularly in Eastern province of Rwanda where fruits and vegetables are mainly produced. The aim was also to determine areas free from B.invadens to help the phytosanitary certificate delivery system and to update provisional national pest list. MATERIALS AND METHODS Site description The experimentation was conducted in the Eastern Province (Rwamagana District in Rwamashyongoshyo village). Eastern Province is major fruits (mangoes, banana, pineapples and citrus) and vegetables production area in Rwanda (table 1) and borders Tanzania and Burundi where B.invadens has been already reported. Crops Southern Province Western Province Northern Province Eastern Province Banana Other fruits Vegetables Source: National Institute of Statistics of Rwanda (NISR,2013) The altitude is around 1600m above sea level. This province is characterized by a tropical weather with temperature ranging between 25 and 30 o C, the dry season is between 1rst June and 30 September, and the heavy rain season starts in March to end in May. The traps were placed in a field of four hectares of mangoes (variety apple mango) and in another one of one hectare of citrus (mixture of varieties: Valencia and Washington). Materials Description of traps -The trap (Chempac bucket trap) used consisted of 2 parts: a yellow one with a single entrance at the bottom and a cylindrical transparent part (See fig. 1). The yellow part contained the lures and insecticides to kill fruit flies. The transparent part had green strings to suspend the trap on the fruit tree. The traps were suspended at around one meter above ground level 3

4 -Three entrance trap -Locally made trap Attractants (Lures) Different attractants (lures) were used during this work The following 4 lures were deployed, all in yellow bucket traps (Tephri traps): -Methyl Eugenol (ME) (plugs) ME is a specific attractant for B. invadens. -Cue lure (CUE) CUE attracts Cucurbitae-feeding Dacus species, as well as B. cucurbitae. -Trimedlure (TML) TML is specific to several species of Ceratitis, including C. capitata (medfly), C. rosa (Natal fruit fly) and C. fasciventris. -3-component lure (C3) that attracts a variety of Dacus and Ceratitis species. Methyl Eugenol (ME) Methyl eugenol is used in insect traps and lure products to attract certain fruit flies such as the Oriental fruit fly on affected food crops. It is naturally occurring in many plants and essential oils, and is a common flavoring ingredient added to foods, candy and gum. No harm is expected from use of this substance in pesticide products as long as users follow label instructions. Methyl eugenol is a natural constituent in many types of plants and fruits consumed by humans and animals, (e.g., anise, nutmeg, mace, pixuri seeds, basil, blackberry essence, bananas, walnuts, citrus, black pepper). Methyl eugenol is also used as a flavoring added to ice cream, cookies, pies, puddings, candy, cola soft drinks, chewing and bubble gum, etc. Here, this product is used to attract fruit flies. Trimed lure(tml) Trimedlure (t-butyl-2-methyl-4- chlorocyclohexanecarboxylate) is a powerful lure for the Mediterranean Fruit Fly (Ceratitis capitata) is used to detect incipient manifestations of the injurious insect. The commercial product consists mainly of four isomers that have a chlorine group and ester substituents on the ring in a trans configuration. Trimed lure provides a successful monitoring program by timing pesticide sprays more accurately. Cue lure (CUE) Cue lure is structurally related to the sex pheromone that female melon flies produce to attract males for mating. The modified pheromone is a more potent attractant than the natural pheromone. The registered manufacturing use product (MUP) will initially be used in producing end products that will slowly release cue lure into the air, thus attracting male s flies and preventing them from mating. Melon flies are a major pest on pumpkins, zucchini, and melons in some country. 4

5 Cue lure shows minimal to no toxic effects in mammals. 3-Compents lures (C3) Table 2: Parapheromones used and targeted group of insects Parapheromones and codes Targeted group of insects Methyl Eugenol (PH-139-1SR) Cue lure (PH-134-1SR) Trimed lure (PH-180-1SR) 3-components lure (PH-180-FM) Methyl Eugenol is used to attract B. invadens, B. zonata (Mangana et al., 2010) and Bactrocera dorsalis (Tan et al, 2012). Bactrocera zonata is not yet established in Sub-Saharan Africa (EPPO, 2005) and Bactrocera dorsalis is occurring in the South East Asia and the Pacific (Boykin et al., 2014). In this experiment, Methyl Eugenol was targeting mostly B. invadens. We use as insecticide the Chempac vapona strip (yellow): insecticide (CAT-M12-4) which active ingredient was Dichlorvos. After being captured, insects were preserved in Alcohol. Except, locally made traps, all parapheromones, chempac vapona strip insecticides and chempac bucket trap were bought from Russell IPM/United Kingdom. Batrocera invadens, Dacus spp and Bactrocera cucurbitae Dacus and Ceratitis spp Different species of Ceratitis including females experimentation site (Rwamashyongoshyo). Parapheromones attracted insects within a diameter of 1 km. Each trap contained one of the four types of parapheromones indicated in Table 1 and one tablet of the chempac vapona strip insecticide (CAT- M12-4). Both crops were at fruit ripening stage. Every week during one month (June, 2013), the number of insects caught in every trap were counted and kept separately in alcohol for data and laboratory identification. Methods and Monitoring process Four traps were placed (2times) in an apple mangoes crop (2 ha) and four other in the citrus (2times also) orchard (1 ha) at the Photo 1: A single entrance Chempac bucket trap (yellow) with Trimed lure and bottles with alcohol to keep insects 5

6 Photo2. Locally made trap Photo3. Entrance trap Results The total number of fruit flies collected from the 8 traps during one month was 267 Then, it is Dacus dacus and B. cucurbitae in cue lure parapheromones with a total of (Table 3). Species trapped depend strongly 74 trapped individuals. Forty two on the kind of lure. The most trapped species was B. invadens (132 insects, 49.4 % of total caught) but only with Methyl individuals (Ceratitis sp + Dacus sp) were trapped with Trimed lure and 7 (only Ceratitis sp.) with 3-Componentslure. Eugenol, 64.4 % being caught in citrus orchard. Table 3: Collected insects Parapheromones Tagetted insects Mango Citrus Total % Methyl Egeunol Bactrocera invadens Cue Lure Dacus species+bactrocera cucurbitae Trimed Lure Ceratitis and Dacus species components lure Ceratitis (females) Total Discussion While previously found at low altitude of Bugarama region (Cassidy, 2010), our results confirmed the presence of Bactrocera invadens in Rwanda and for the first time in the Eastern Province where it seems to be the more abundant species before indigenous fruit flies. The Eastern Province may be a good ecological zone 6

7 for B. invadens due to the different fruits and vegetables that are produced there and because this fly has many possible host plants (Georgen et al., 2011) including ripening banana which is the most cultivated fruit in Eastern Province of Rwanda. It is difficult to determine the actual origin of this pest because it was found in Kenya in 2003 (José et al.,2013) in Burundi in 2009 (Delatte et al.,2013). A great part of the fruits and vegetables consumed in Rwanda comes from Burundi, Tanzania and Uganda which could explain the introduction of this pest into Rwanda. A part of them enter the country by entry points that are not officially controlled and are not inspected. This may probably explain the presence of B.invadens. According to José et al. (2013), Bactrocera invadens became the major pest of fruits and vegetables in African countries due to its polyphagous nature. The highest prevalence of Bactrocera invadens compared to other fruit flies species also was reported in Mozambique by José et al. (2013), in Kenya by Ekesi et al. (2009) and in Tanzania by Mwatawala et al. (2006). The difference in numbers of insects found in different traps in two 2 different crops cannot only be explained by the host preference but also due to the capacity of parapheromones to attract pests from other crops located in an area of 1km of diameter from the position of the traps. Conclusion Bactrocera invadens is occurring in Rwanda not only in the lowest region of Rwanda (Bugarama) but also in Eastern Province (middle). A pest monitoring systems should be done through the whole country to determine the level of its presence and the risk associated. Information about its distribution (mapping) in Rwanda would help to update national provisional pest list and facilitate the delivery of phytosanitary certificate system. Acknowledgment The authors are grateful to Appui à la Filière Horticole au Rwanda under Belgian Technical Cooperation for its support and to Rwanda Horticulture Development Authority for its technical assistance. This paper is the 313 BRC publication number of the Biodiversity Research Center, Université catholique de Louvain/Belgium. References Aluja, M. and Norrbom, A Fruit Flies (Tephritidae): Phylogeny and Evolution of Behavior. CRC Press, Florida, 984p. Benjamin, B.K., Kelvin, B.M., Kwame, A-N and Daniel Farmers 7

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