Efficacy of African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae) in reducing losses due to frugivorous fruit flies (Diptera: Tephritidae) in smallholder mango production systems in Eastern Tanzania

ABSTRACT

Fruit flies (Diptera: Tephritidae) are dipteran insects that cause high losses of fruits and vegetables in the tropical and subtropical regions of the world. As quarantine pests, fruit flies affect export markets because trade regulations hamper export of fruits from areas with occurrence of fruit flies. We compared the effectiveness of Oecophylla longinoda with the insecticide; imidacloprid for the control of Bactrocera dorsalis in a 6-year-old orchard of mango cultivar ‘Apple’. Mango samples at different developmental stages were collected between September and November in 2012 and between November 2013 and January 2014 at a three-week interval between sampling dates. Every fruit was cultured in a separate individual plastic container containing approximately 500 g sieved sterilised sand. Three weeks later, larvae and pupae were sieved from sand and counted. In both years, significantly higher (P < .0001) incidences and infestation rates were recorded in the control plots when compared to the trees protected with insecticides and O. longinoda. Incidences and infestation rates did not differ significantly (P > .05) between insecticide and weaver ants protected fruits, implying that O. longinoda was as effective as imidacloprid in suppressing the population of fruit flies. Peak fruit fly incidences and infestation rates coincided with the ripening stage of mango fruits. Our results have shown that the incidences and infestation rates on incubated mango fruits were lowest in the O. longinoda and the imidacloprid protected trees. Thus, O. longinoda is an effective bio-control agent that could be exploited to serve as a vital Integrated Pest Management component on mango orchards.

KEYWORDS:

• Bio-control
• imidacloprid
• incidences
• infestation rate
• management practice

Acknowledgements

We thank Mr E. Nsami, the Head of the National Biological Control Unit, Kibaha, Tanzania for providing space and work facilities for fruits culturing in the laboratory. We also thank the support extended by Jesca Isaya and Saadani Mohammed during field and laboratory activities. We would also like to thank the anonymous reviewers for their constructive comments. Dr Lars Bjørnsbo of Ecostyle A/S provided spinosad for the control of P. megacephala.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The study was funded by DANIDA through the Project: DFC No. 10-025AU.