Resistance to lambda-cyhalothrin in the lady beetle Eriopis connexa (Germar) affects its longevity and reproductive output

The performance of Eriopis connexa (Germar) (Coleoptera: Coccinellidae) resistant to l-cyhalothrin was studied when recovered from knockdown effect within 24, 48 and 72h periods after treatment. Further, the development of the progeny produced was also studied and fertility life table parameters determined. The recovering rate from knockdown was nearly 69.4% for resistant population (R) with greater recovering rate after 48h from treatment with λ-cyhalothrin. Females from susceptible population (S) lived longer and produced about 50% more eggs compared to resistant beetles. Resistant females recovered from knockdown effect within 24, 48 and 72h intervals post-treatment or without insecticide treatment produced similar number of eggs and exhibited similar longevity among them. Despite differences on egg production and longevity between resistant and susceptible females, the progeny produced did not exhibit consistent differences for development and survival of larvae and pupae, and adult weight in favor of either S- or R-population. The population growth parameters estimated through the fertility life table for S-, R- and R-recovered females from knockdown 24h after treatment (R24) resulted in higher intrinsic rate of population growth (r_m) and lower mean generation time (T) for resistant females compared to susceptible females; while, the net reproductive rate (Ro) was similar across populations. Therefore, the consistent difference regarding the resistance exhibited by E. connexa are related to lower egg production and shorter longevity irrespective of knockdown effect. Further, due to shorter generation time for R-population, the calculation resulted in greater r_m for resistant females indicating high potential for population growth despite overall low fecundity.