The aim of this study was to analyze the morphologically the fatty body of fourth-instar Anticarsia gemmatalis larvae under light, transmission and scanning electron microscopy. Two distinct portions of the fat body were detected: the parietal (PA) and perivisceral (PV). The PA, the parietal portion, presented a long-stripped shape located below the tegument and lateral to the digestive tube. The PV, rarely observed, was in dorsal region, adhered to digestive wall. Both the portions were constituted of only one cellular type, the trophocytes. These cells in the PA were organized in one layer of thickness showing cylindrical contiguously morphology, whereas the PV was comprised by a mass of small cells, superposed as clusters. Both the portions were covered by a layer of connective tissue, grouping the trophocytes and keeping them separated from the hemolymph. The cytoplasm of the trophocytes from the PA presented acidophilic stain, while the basophilic cytoplasmic of the trophocytes from the PV was due to the large amount of rough endoplasmic reticulum. From the results, it could be concluded that the fat body presented morphological and ultrastructural differences according to the portion and that these features could characterize distinct functions.

Os efeitos iniciais da infecção por AgMNPV nas contagens total e diferencial dos hemócitos em Anticarsia gemmatalis (Lepidoptera: Noctuidae) foram estudados. O número total de hemócitos não diminuiu nas larvas infectadas, como ocorreu nas larvas não infectadas. Nas larvas infectadas, os tipos de hemócitos apresentaram as seguintes freqüências: plasmatócitos - 47,8%, esferulócitos - 25,9%, granulócitos - 15,8%, oenocitóides - 7,2%, prohemócitos - 2,8%, vermiformes - 0,5%. Apenas a porcentagem de granulócitos foi diferente entre larvas infectadas e não infectadas, indicando que estas células responderam rapidamente à infecção viral inicial. Estes resultados mostraram o papel efetivo que dos hemócitos na resposta de A. gemmatalis à infecção por AgMNPV. A compreensão dos mecanismos imunológicos deste inseto é uma ferramenta importante para compreender seu controle biológico.

The initial effects of the infection by AgMNPV in the total and differential counts of the hemocytes in Anticarsia gemmatalis (Lepidoptera: Noctuidae) larvae were studied. The total number of the hemocytes did not decrease in infected larvae, as it occurred in non infected larvae. In infected larvae, the hemocyte types showed the following frequencies: plasmatocytes - 47.8%, esferulocytes - 25.9%, granulocytes - 15.8%, oenocytoids - 7.2%, prohemocytes - 2.8%, vermicytes - 0,5%. Only the percentage of the granulocytes was different among infected and non infected larvae, indicating that these cells responded quickly to the initial viral infection. These results showed the effective role of the hemocytes in the response of the A. gemmatalis to the infection by AgMNPV. The comprehension of the immunological mechanisms of this insect is an important tool to understand its biological control.