Toxicity and fitness evaluation of Chrysoperla carnea resistant strains on cotton mealy bug Phenacoccus solenopsis Tinsely

Research was conducted to select chlorantraniliprole and bifenthrin resistant strains of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) at Bahauddin Zakariya University, Multan, Pakistan. Moreover, fitness parameters of resistant C. carnea were evaluated after feeding on 2nd instars nymph of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). Two to three day old C. carnea larvae were used in each topical bioassay. The raw data of biological parameters were analysed using an age stage, two sex life table. After 16 and 13 rounds of selection, the Chlo-Sel and Bife-Sel strains of C. carnea developed 91- and 2.19-fold resistance level, respectively compared with the UN-Sel strain. Biological parameters such as larval duration (days), pupal duration (days), female longevity (days), male longevity (days), adult pre-oviposition period (APOP) (days), total pre-oviposition period (TPOP) (days), oviposition (days), reproductive female ratio (RepF/Fn), and fecundity/female (F) were significantly different while pre-adult female (days), pre-adult male (days), and female ratio (Nf/N) was not significantly different among all strains. Demographic parameters such as finite rate of increase (λ), mean generation time (T), intrinsic rate of increase (r), net reproductive rate (Ro), and gross reproductive rate (GRR) were significantly different while doubling time (DT) was significantly similar among all strains of C. carnea. This information could be helpful in developing and promoting the use of insecticide resistant strains of C. carnea for the management of P. solenopsis under field conditions. Moreover, knowledge of fitness advantages will be helpful in IPM for the development of control strategies against P. solenopsis. In order to explore the practical relevance of our findings, more research ought to be conducted.