Aspectos biológicos de duas espécies de joaninhas afidófagas (Coleoptera: Coccinellidae) alimentadas com presas alternativas em laboratório

Abstract

The biological control of insect pests has assumed increasingly important role in agriculture, due to the need to reduce the use of pesticides, aimed not only at improving the quality of food and the reduction in production costs, but also the preservation of the environment . The mass rearing and release in the field of certain natural enemies is a technique that has been increased worldwide. Knowledge of biology, behavior and breeding techniques can significantly improve the potential of these predators, but that adequate natural diet is one of the problems for the creation of ladybugs afidófagas. In this context, the present study was the overall objective to study the biology and functional response of Coccinellidae, and these issues addressed in Chapters I and II, respectively. In Chapter I, the studies were conducted for the following purposes: to evaluate living larvae of Drosophila melanogaster Meigen fly (Diptera: Drosophilidae) as prey alternative to creating Coleomegilla maculata DeGeer and Eriopis connexa (Germar), evaluating the effect of this diet compared to unfeasible eggs and frozen Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) on biological characteristics of ladybugs. The experiments were conducted with adults from generation 1, which were maintained in a room (25 1°C, 70 ± 10% RH and 12 hours photophase). It was adopted a completely randomized design with three treatments for each species of ladybug and 40 repetitions in each development phase. The treatments consisted of three kinds of alternatives based diet D. melanogaster larvae, A. kuehniella eggs and also the mixture of both diets mentioned above. We evaluated different biological parameters of the 1st and 2nd generations of both species of ladybugs referring to the pre-oviposition period, egg stage, larval stages, pre-pupa and pupa, biological cycle and adulthood. No significant difference in biological parameters of E. connexa of generations 1 and 2, with respect to the respective diets provided. The same can be observed for C. maculata in both generations. In Chapter II, the studies were conducted for the following purposes: to determine the functional response of C. maculata and E. connexa fed with two alternative preys: D. melanogaster fly larvae and eggs of A. kuehniella, to evaluate their predatory capacity to grant the optimization of mass rearing. To determine the effect of different prey densities offered in the food consumption of the larvae and the adult E. connexa and C. maculata were conducted five experiments corresponding to the larval instars and adults of these ladybugs in experimental design. In general the two food sources tested in this work did not affect the functional response of E. connexa and C. maculata so to harm the creation. The eggs of A. kuehniella had conservation problems during use; probably the high rates of mortality C. maculata between treatments have been given toxicity in intake of these eggs. However, D. melanogaster larvae proved to be an alternative food source.