ABSTRACT In two independent bioassays, size and flight ability of parasitoids reared on eggs of Corcyra cephalonica for 19 generations and parasitoids reared on a natural host (Spodoptera frugiperda eggs) for 250 generations were compared as fast quality control procedures for insect rearing. The size of parasitoids was examined by morphometric analysis using a stereoscope. Length and width of the wings, right hind tibia, and the body of 20 individuals (males and females) were measured. In the analysis of flight ability, parasitoids were divided into three groups: individuals able to fly ("flyers"), individuals that did not fly but had no visible deformation ("walkers"), and individuals with visible deformation ("deformed"). We observed that parasitoids were larger when reared on the natural host than on the factitious host for all evaluated morphological characters. However, there was no significant difference between the treatments regarding the number of "flyers", "walkers" or "deformed" parasitoids. This indicates that even though the rearing of T. remus on a factitious host affects parasitoid size, it does not necessarily affect its flight ability and therefore suggests that C. cephalonica is suitable as a factitious host for mass rearing of T. remus. Other biological parameters still need to be evaluated, such as host finding ability, parasitism capacity, and parasitoid field efficacy in order to provide a more complete picture of the effects caused by a host change. However, because fast laboratory tests are needed in rearing facilities, the one used in this study might be useful to rapidly assess parasitoid quality.

Análogos do hormônio juvenil têm sido testados como reguladores de crescimento de insetos em Bombyx mori, com vistas ao incremento da produção de seda. Estes produtos químicos, quando aplicados em pequenas ou moderadas doses, promovem prolongamento do último ínstar larval. O presente estudo visou o entendimento das conseqüências fisiológicas na produção do bicho-da-seda da linhagem C115xN108 face a aplicação de methoprene, um análogo do hormônio juvenil, através da determinação de seus efeitos sobre o desenvolvimento larval e a produção de seda. Methoprene foi aplicado, por via tópica, 48 horas após a quarta ecdise larval, sobre o tegumento dorsal do segundo segmento torácico dos insetos, em sete doses entre 0 e 20 ng de i.a. Methoprene influenciou positivamente a duração do ínstar e o ganho de peso dos insetos. A aplicação de 1 ng de methoprene resultou nos pesos mais elevados de glândulas sericígenas (1,89 g), casulos cheios (2,36 g), casulos vazios (0,62 g) e pupa (1,74 g). Comparativamente ao controle, o incremento na produção de seda pelo uso de 1 ng de methoprene (aproximadamente 24%) foi mais acentuado que os correspondentes efeitos negativos na taxa de encasulamento (aproximadamente 12%).

Juvenile hormone analogues have been tested as insect growth regulators in silkworm (Bombyx mori), seeking an increment of silk production. These chemical products, when applied in small or moderate rates, promote the extension of the last larval instar. To understand the physiologic consequences on silk production by the silkworm strain C115 x N108, the application of methoprene, a juvenile hormone analogue, was performed to evaluate its effects on larval development and silk production. Methoprene was topically applied 48h after the fourth larval ecdysis, on the dorsal integument of the 2nd thoracic segment of the insects, at seven rates between 0 and 20 ng a.i. Methoprene influenced positively the duration of the fifth instar and the weight gain of the insects. The application of 1ng methoprene resulted in the heaviest silkglands, cocoons, shell cocoons and pupae weights. Comparatively to the control, the increment on silk production (approximately 24%) by the use of 1ng methoprene was more accentuated than the corresponding negative effects on the cocooning rate (approximately 12%).