Higher longevity and fecundity of Chrysoperla carnea, a predator of olive pests, on some native flowering Mediterranean plants

Biological control is the use of natural enemies, such as predators, of crop pests. For instance, Chrysoperla carnea (Stephens) is a major predator of olive grove pests. To favor the abundance of C. carnea, flowering plants should provide them with carbohydrates. However, there is a lack of knowledge on the biology of flowering plants that grow in olive groves. Therefore, we studied in the laboratory 11 native Mediterranean plants commonly found in traditional olive orchards as food sources for C. carnea adults. Male and female longevity and female lifetime fecundity were measured on a daily base. Plant nectar and pollen were quantified by high-performance anion-exchange chromatography analysis (HPAEC-PAD). Our results show that the longevity of C. carnea females was higher, of 17 days, when fed with Conopodium majus flowers, and of 14 days when fed with Lonicera hispanica flowers. Female fecundity was higher for C. carnea individuals fed with C. majus, giving 71 eggs, and with Foeniculum vulgare, giving 66 eggs, than for C. carnea individuals fed with L. hispanica (19 eggs) and Asparagus acutifolius (4 eggs). These findings are explained by the higher concentration of trehalose in plant nectar and pollen. To our knowledge, this is the first study evaluating the sugar profile and content of Mediterranean flower plants as food resource of C. carnea adults indicating that trehalose content in pollen and nectar has a key role in C. carnea fecundity and longevity.