Developmental temperature responses of Chrysoperla agilis (Neuroptera: Chrysopidae), a member of the European carnea cryptic species group

Chrysoperla agilis Henry et al. is one of the five cryptic species of the carnea group found in Europe. Identification of these species is mainly based on the distinct mating signals produced by both females and males prior to copulation, although there are also morphological traits that can be used to distinguish among different cryptic species. Ecological and physiological cryptic species-specific differences may affect their potential as important biological agents in certain agroecosystems. To understand the effects of temperature on the life-history traits of C. agilis preimaginal development, adult longevity and reproduction were studied at seven temperatures. Temperature affected the development, survival and reproduction of C. agilis. Developmental time ranged from approximately 62 days at 15 °C to 15 days at 30 °C. Survival percentages ranged from 42% at 15 °C to 76% at 27 °C. One linear and five nonlinear models (Briere I, II, Logan 6, Lactin and Taylor) used to model preimaginal development were tested to describe the relationship between temperature and developmental rate. Logan 6 model fitted the data of egg to adult development best according to the criteria adopted for the model evaluation. The predicted lower developmental threshold temperatures were 11.4 °C and 11.8 °C (linear model), whereas the predicted upper threshold temperatures (Logan 6 model) were 36.6 and 36.9 °C for females and males, respectively. Adult life span, preoviposition period and lifetime cumulative oviposition were significantly affected by temperature. The effect of rearing temperature on the demographic parameters is well summarized with the estimated values of the intrinsic rate of increase (r_m) which ranged from 0.0269 at 15 °C to 0.0890 at 32 °C and the highest value recorded at 27 °C (0.1530). These results could be useful in mass rearing C. agilis and predicting its population dynamics in the field.