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Effect of Sublethal Dose of Diflubenzuron and Azadirachtin on Various Life Table Attributes of Culex quinquefasciatus (Diptera: Culicidae)

Suman, D.S., Parashar, B.D., Prakash, Shri
Journal of medical entomology 2010 v.47 no.6 pp. 996-1002
Culex quinquefasciatus, diflubenzuron, azadirachtin, sublethal effects, life tables, males, females, instars, adult insects
The exposure of sublethal doses (25% emergence inhibition) of diflubenzuron (DFB) (0.0002 mg/liter) and azadirachtin (AZD; 0.0079 mg/liter) insect growth regulators was provided to late third—early fourth instars of Culex quinquefasciatus till emergence of adults to find out the effects on various biological and life table attributes of adults, and comparison was made with control (CTL) as well. Life expectancy of both males and females of DFB survivors was significantly less in comparison with AZD and CTL ones; however, it was nonsignificantly different between CTL and AZD. In all treatments, males were shorter lived than females of their respective treatments. DFB survivors showed significant reduction in number of blood-fed females, resulting in minimum of oviposition days, total number of egg rafts, total number of eggs, eggs per egg raft, eggs per female life span, and eggs per female per day than survivors of both AZD and CTL significantly, but these parameters did not differ significantly between CTL and AZD, except eggs per egg raft. The net reproductive rate, intrinsic rate of increase, and finite rate of increase were significantly less in DFB than rest of the survivors, whereas doubling time for generation was significantly high; however, difference in mean generation was not significant among them. This study reveals that DFB has the potency to affect severely the various life table attributes at sublethal dose, but AZD does not have such effectiveness at similar sublethal dose against Cx. quinquefasciatus.