Flowers of Apiaceous species as sources of pollen for adults of Chrysoperla externa (Hagen) (Neuroptera)

Abstract

The selection of appropriate flowering plants as sources of pollen and nectar for beneficial insect predators and parasitoids is essential in maintaining conservation biocontrol in agroecosystems. The objectives of the present work were: (i) to evaluate the capacity of Chrysoperla externa (Hagen) adults to feed on pollen of three different Apiaceous species (dill, coriander and fennel), and (ii) to evaluate the effects of the provision of Apiaceous flowers on the longevity and reproductive parameters of adult insects under laboratory conditions. C. externa adults (one male and one female) were placed in a polypropylene cage containing a cluster of approximately 200 flowers from one of the three test species, and the oviposited eggs were counted and collected every three days. Egg viability was determined and samples of eggs were used to rear F2 adults. The experiments were conducted at 25±1°C, with 70±10% relative humidity and 12h photoperiod, and ten repetitions were performed for each treatment. The results showed that C. externa adults may survive and reproduce up to the third generation by feeding only on resources provided by flowers of the three Apiaceous species tested. All treatments exerted similar effects on the longevity, duration of preoviposition and oviposition periods, number of eggs/female, number of eggs/female/day and viability of the eggs of F1 insects. The results of this study indicate that dill, coriander and fennel would work well as insectary plants and promote conservation biological control programs aimed at using C. externa to control crop pests.