Development and mechanisms of resistance in peach fruit fly bactrocera zonata (saunders) to malathion, lambda-cyhalothrin and spinosad / Hussein Mohamed Nasouri ; Supervised Hany Mahmod Ashour Badawy , Dalia Ahmed Abdelsalam Barkat , Eman Mohamed Moustafa Ali Radwan

Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Economic Entomology and Pesticides

The first part of the present study was undertaken to investigate the potential of peach fruit fly, bactrocera zonata, to develop resistance to malathion, lambda-cyhalothrin and spinosad under laboratory conditions and the possible mechanisms of resistance. Three resistant strains were established; the malathion-resistant strain (M-R) (Resistance ratio (RR): 52-fold after eight generations of selection), the lambda-cyhalothrin-resistant strain (L-R) (RR: 12-fold after six generations of selection) and the spinosad-resistant (S-R) (RR <3-fold after six generations of selection). The L-R and S-R strains did not show cross-resistance to malathion. The selected strains were more tolerant to methomyl and deltamethrin, and more susceptible to dimethoate, lambada-cyhalothrin and spinosad. Piperonyl butoxide (PBO) had no synergistic effects for malathion and spinosad, while it increased the toxicity of lambda-cyhalothrin in both susceptible and L-R strains; and the synergistic effect was higher in L-R strain. Biochemical analysis revealed that esterase activity in the M-R strain was higher than that in the susceptible strain; these differences were significant in the eighth generation and in females of the sixth generation. There were no significant differences in esterase activity between the L-R and S-R strains and the susceptible strain. No significant differences in acetylcholinesterase (AChE) activity were found among males of all studied strains. However, significant differences were found between females of the third generation of the M-R and S-R strains and females of the susceptible strain

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