Quality traits of the lady beetle <i>Eriopis connexa</i> (Germar) resistant to pyrethroids over 130 generations of rearing

Abstract Augmentative biological control requires the rearing of large quantities of natural enemies to meet customers' demands. We hypothesise that successive generations of an insecticide‐resistant lady beetle population, under constant physical conditions and fed alternative prey, could compromise its quality as a natural enemy. Adaptive costs of resistance are particularly high in insecticide‐resistant populations. The predatory lady beetle, Eriopis connexa (Germar), exhibits resistance to λ‐cyhalothrin (EcViR), and others pyrethroids. We compared the biological and predatory traits of the EcViR population to those of a field‐collected and susceptible population (EcCV). During 35 days of observations, when females from both populations faced food shortages, EcViR females demonstrated higher fecundity and similar survival rates. Predation of the aphid, Lipaphis pseudobrassicae (Davis), resulted in a similar response for both populations and greater aphid consumption by EcViR beetles in the presence of λ‐cyhalothrin residue. Rearing larvae and adults at three constant temperatures (18, 25, and 32°C) resulted in similar developmental times between populations, but adult EcCV beetles were larger and produced more eggs at 25 and 32°C. The results show that food shortages did not affect the reproductive output or the developmental time at 18, 25, and 32°C in EcViR compared with EcCV. Nevertheless, egg production at 25 and 32°C was lower for EcViR females than for EcCV. Among the studied traits, only an effect on fecundity was observed, as predicted previously, due to the adaptive cost of resistance in EcViR, which became more evident at higher temperatures.