Estudo da ecologia de infecção dos nematóides entomopatogênicos Heterorhabditis riobravus e Steinernema carpocapse (Rhabditida: Heterorhabditidae) em Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Abstract

Aphitobius diaperinus (Panzer), known as cascudinho or "lesser mealworm" colonizes the substrate found at farms, developing itselves in high populations, causing sanitary and economical problems. They affect the health and performance of the birds, being also transmitters of diseases. Their control is based on the application of insecticides, which increase the production costs and are harmful to the animals. Therefore, the infectivity of Heterohabditis riobravus and of Steinernema carpocapsae in front the life stages of larvae, pupae and adult of

21 this insect - for the first mentioned species of nematode - and of larva and adult for the second species, were evaluated in laboratory, using the following types of substrate: small plane + ration, filter paper and earth. The objective was to determine the degree of virulence of the J Is of these nematodes in each treatment. The results indicated that so much H. riobravus, as well as S. carpocapsae presented potential to infect all of the life stages of development of the species A. diaperinus analyzed; and that the infective juvenile of S. carpocapsae were shown more efficient against larvae and adults of A. diaperinus, that the infective juvenile of H. riobravus, in all of the types of tested substrate. As already observed in another study, the immature life stages were shown to be more susceptible to the nematodes than the adult life stage. When we compared the treatments with the two species of adult individuals constituted by the nematodes in the substrate of small plane + ration, natural environment for the species to be controlled, we verified that DL50 and DL90 of J Is of S. carpocapsae, corresponded respectively only 54.18% of DL50 and to 40.34% of DL90, found for the treatment involving the nematode of the species H. riobravus.