SYNERGISTIC EFFECT OF PHYTO-CHEMICALS AGAINST CITRUS FRUIT FLY BACTROCERA ZONATA (DIPTERA: TEPHRITIDAE).

Fruit fly (Bactrocera zonata) is a destructive pest of citrus fruits. Use of synthetic insecticides against fruit fly infestations has created different ecological problems such as the development of insecticide resistance, eradication of beneficial fauna and human health hazards. This situation necessitates looking for alternate biorational fruit fly management tools such as botanical insecticides. This laboratory study was aimed at determining the toxicity of some selected plant extracts (i.e. Azadirachta indica A. Juss., Nigella sativa L. and Citrullus colocynthis (L.) Schrad) alone and as binary combinations against B. zonata adults. The study was conducted in the at Department of Entomology, University of Sargodha, Pakistan in July to September, 2019. Bioassay results showed that aqueous extract of A. indica was most toxic to B. zonata adults with a median lethal concentration (LC50) of 383.3 μl/g of artificial diet, followed by C. colocynthis and N. sativa with LC50 values of 656.3 and 734.2 μl/g of artificial diet, respectively. Bioassays with binary combinations revealed that A. indica with C. colocynthis (ratio 1:1) showed a synergistic effect exhibiting a LC50 value of 293.1 μl/g of artificial diet. However, all other treatment combinations showed an antagonistic effect. It is suggested that the mixture of botanical extracts should be used carefully as they may sometimes reduce the efficacy of each other upon mixing. These results can thus be used in the development of potential botanical formulations against insect pests such as fruit flies. [ABSTRACT FROM AUTHOR]