Functional response of Telenomus remus Nixon(Hymenoptera, Scelionidae) to Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae) eggs: effect of female age

Functional response of Telenomus remus Nixon (Hymenoptera, Scelionidae) to Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae) eggs: effect of female age. Functional response of 24-h and 48-h-old Telenomus remus adults was studied on Spodoptera frugiperda eggs. The study was carried out in climatic chamber regulated at 25 ± 1°C, 70 ± 10% RH and 12:12h (L: D). Females of T. remus were honey fed and individualized in glass vials along with 25, 50, 75, 100, 150, 200, 250 or 300 eggs of S. frugiperda for 24 h. Complete randomized design with ten replications was adopted. The parameters evaluated to construct the functional response curve were daily average parasitism, searching rate and oviposition time. It was observed that the higher the egg density, the higher the parasitism for 24-h and 48-h-old females although there was a tendency of parasitism stabilization at 150-egg density. The results showed a type II functional response curve for both 24-h and 48-h-old female.

Sexual behavior of the digger wasp Sphex ingens Smith (Hymenoptera, Sphecidae)

A species' mating system depends on its spatial distribution and temporal availability of mating opportunities, as well as on the resources that create these opportunities. In addition, for many species, courtship is driven by specific behaviors that precede and follow copulation. Although Sphex ingens is a taxonomically well known species of digger wasp, its ecology and behavior remain poorly known. Hence, we analyzed patterns and trends of sexual behavior, in order to understand whether courtship can persist in a polygamous mating system. We monitored by video wasp populations in Ilha Grande, southeastern Brazil. Based on the observed behaviors, we calculated stochastic probabilities with a Markov chain to infer on behavioral trends. We recorded four behavioral phases based on 19,196 behavioral acts observed in 224 copulation attempts. There were no significant differences in common behavioral acts between males and females. The copulation patterns, conflicts, and trends observed in S. ingens clearly show the influence of sexual selection in its promiscuous mating system.

CONTROLE INTEGRADO DE SPODOPTERA FRUGIPERDA (SMITH & ABBOTT) UTILIZANDO-SE O PARASITÓIDE TELENOMUS REMUS NIXON

Este estudo foi conduzido em 1996 e 1997 para avaliar a eficiência da liberação de Telenomus remus Nixon (cerca de 200.000 adultos/ha), sozinho ou integrado ao vírus de poliedrose nuclear de Spodoptera frugiperda (VPNSf) ou a um inseticida químico seletivo, para o controle de Spodoptera frugiperda (Smith & Abbott). Os experimentos foram conduzidos em delineamento experimental de blocos ao acaso, com seis tratamentos e quatro repetições. Foram avaliados os danos provocados pela praga às folhas (escala de 0 a 5) e o rendimento de espigas. De maneira geral, os danos provocados pela praga foram significativamente superiores nas parcelas testemunhas (nota média de 2,94). Não houve diferença significativa entre os demais tratamentos (média 1,04). De maneira semelhante, houve diferença significativa no rendimento de espiga entre testemunha (7.165 kg/ha) e demais tratamentos (9.084 kg/ha). Não houve efeito dos tratamentos no comprimento da espiga e no dano às espigas.