Efficacy of Artificial diets on biological characteristics of oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) in India

Bactrocera dorsalis (Hendel) is one of the important pests of great economic significance causing serious fruit and vegetable damage in tropical and subtropical areas of the world occurs. This study aimed to investigate the effect of high fat diet on various physiological traits of females and a shift of sex ratios in favour of males to benefit biological control of this pest species. B. dorsalis individuals were collected from Punjab Agricultural University (PAU), Ludhiana, Punjab and the effect of coconut oil-based artificial diets differing in their relative levels of fat (5%, 10% and 20%) on stage-specific development, survival, hatchability were analysed at 21 °C, 65% Relative Humidity. The male: female (M/F) sex-ratios from individuals emerging from each of these diets were also scored. The findings of the study showed that B. dorsalis larvae and adults were able to survive on all three diets, although the stage-specific development and survival varied with High Fat Diet (HFD) concentration. Diet with 20% fat concentration showed most delayed development relatively to 10% and 5% concentration diet. The laboratory test showed that ingestion of fat significantly increased the development time (egg-larvae-pupae to adult) and caused increased mortality in pre-adult stages. A decrease in percentage pupation and adult emergence was also observed. Moreover, the data showed a significant shift in M/F ratios for regular food, HFD 5%, and HFD 10% with 46.7%, 45.7%, and 45.9% respectively and all female biased. Only HFD 20% produced male biased ratio of 74.4%. Adults fed on 20% HFD produced significantly fewer eggs as well as reversed the male: female sex ratio from 1:1.28 to 2.9: 1. The HFD diet elicited a higher adult lipid content, lower pupal production, adult emergence, and longer development, significantly affecting physiology of fruit flies. Field efficacy trials showed significant results with bait trap method and significantly increased the fruit yield by 51.09 Kg/tree as compared to the control. Hence, the present study illustrated the potential of HFD which can be exploited in integrated pest management strategies for capturing fruit fly pests of economic significance.