Quality traits of the lady beetle Eriopis connexa (Germar) resistant to pyrethroids over 130 generations of rearing
Description
The efficacy of the natural enemy may decline after numerous generations of laboratory culture. In addition, insects resistant to insecticides might show diminished performance due to the consequences of insecticide resistance. The insecticide-resistant population of the lady beetle Eriopis connexa (Germar) (EcViR) is metabolically resistant to λ-cyhalothrin and has been kept alive in a lab for over 130 generations, resulting in a 260-fold increase in resistance. Therefore, we compared the biological and behavioral characteristics of the EcViR population with those of a field-collected, cyhalothrin-susceptible population (EcCV). Females from both groups had comparable survival rates during 35 days of monitoring, regardless of food scarcity, but EcViR females demonstrated greater fecundity. The adults from both groups showed a type II functional response when they ate the turnip aphid, Lipaphis pseudobrassicae Davis. This happened whether λ-cyhalothrin was present or not. Nonetheless, EcViR individuals exhibited a greater rate of aphid consumption compared to EcCV, irrespective of the λ-cyhalothrin residue. The period of larval growth was comparable among populations when reared at 18, 25, and 32 °C. On the other hand, EcCV females were bigger than EcViR females when they were raised from larvae at 18 and 25 °C, and EcCV females laid more eggs at 25 and 32 °C. The results show that the EcViR individuals kept their ability to hunt and reproduce even after 100 generations of development in the lab. Conversely, the fecundity of EcViR females was diminished when provided ad libitum, grown from larvae, and maintained at 25 and 32 °C. Consequently, the findings support the idea that the predation rate is unaffected in the resistant population following laboratory rearing. Nevertheless, the adaptation cost of resistance influences the fertility in the resistant population, becoming more pronounced at varying temperatures.