fly

Male fruit fly: Bactrocera dorsalis

Horticulture sector has been accorded high priority in Uganda’s economic development plans for strategic contributions to national economy in terms of foreign exchange, employment opportunities, rural development and food and nutritional security. However, fruit flies inflict serious damages on a wide range of fruit and vegetable crops in Uganda. Losses in commercial exotic varieties of mangoes can be as high as 100% mainly by Bactrocera dorsalis (Diptera Tephritidae), a pest originating from South East Asia, that has now become predominant having competitively displaced local fruit fly species in most host plants.  Effective options for management of fruit flies are lacking in the country. Farmers have resorted to blanket cover sprays of chemical pesticides to no avail. Pesticides pose untold environmental concerns and often result in undesirable chemical residues in produce implying noncompliance to Maximum Residue Levels (MRL) legislated in most overseas markets. Fruit flies are also quarantine pests and attract stringent quarantine restrictions in such lucrative markets. Presence of fruit flies thus, limit expansion of trade of fresh fruits and vegetables for both domestic and export markets. The millions of fruit tree seedlings supplied countrywide through Operation for Wealth creation (OWC) and the Soroti Fruit Processing Factory both of which are well meaning initiatives might prove futile if we do not decisively address the menacing fruit fly problem.

 

bad fruitFF

Recently, AMOCAS Limited, in a public-private-partnership with National Agricultural Research Organization (NARO) produced a novel protein bait, derived from brewery waste yeast that has proved highly effective in fruit fly monitoring and suppression (control). Tephritidae fruit flies require protein for normal growth but females need more protein for egg maturation hence the greater attraction of the protein bait for females than males, a behavior that has been exploited for their control. Bait comparison studies showed that the novel product was comparable and in some cases superior to imported protein bait products in fruit fly attraction. Application of novel bait reduced fruit fly infestation from 100% to less than 5% in guava and from nearly 100% to less than 20% in mangoes.  The bait is applied using ‘spot spray technique’ attracting flies from a distance and overall coverage of plant canopy is not required as opposed to conventional chemical pesticides. The bait is therefore environmentally sound being less hazardous to beneficial organisms (natural enemies and pollinators), spray applicator and consumers owing to minimal chemical residues in produce. Bait production has been limited to laboratory work, producing only enough for research purposes. The need to advance to the next stage of mass production and commercialization cannot be overemphasized.  This would entail acquisition, installation and operationalization of a bait production plant to produce sufficient quantities to meet farmer’s needs countrywide.  Additionally, the novel product is rich in protein (>50%) and therefore the protein bait makes an excellent substitute for scarce protein sources of soybean and mukene fish (Rastrineobola argentea) used in livestock feed formulations. The excess, unutilized reformulated product will be sold to livestock farmers to boost production. This alleviates potential threat on food and nutrition security that would arise from continued use of such limited resources.

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  Protein bait of various formulations derived from frothy brewery waste yeast

Overall, the proposed intervention helps to manage pestiferous fruit flies, generates livestock feed ingredients, and solves disposal and environmental challenges at the breweries posed by copious amounts of waste yeast. Training of farmers, plant protection, quarantine and extension officers will be a key consideration to ensure production of quality fruit and vegetables for both local and export trade. The intervention will stimulate increased acreages of mangoes and other commercial fruits and vegetables. This will lead to enhanced availability of healthy foods, increased farmers’ incomes and national revenues through foreign exchange earnings and above all creation of employment in the fruit and vegetable industry. The ability of Uganda to produce its own protein bait from cheap and locally available materials is a more sustainable strategy for fruit fly management than dependence on expensive imported chemical insecticides and protein baits largely affordable by local growers. The total cost estimates of the three-year project is US$ 499,813 (Ug. Shs. 1,874, 300,000). This capital investment would be recoverable in less than three years.

By Pontiano Sebba Nemeye, PhD, Entomologist / Agricultural Consultant, Principal Investigator based at Mbarara University of Science and Technology (MUST),     Email: psnemye@gmail.com

 

 

 

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