Cotesia flavipes Cameron (Hymenoptera: Braconidae) alters the nutrients in the hemolymph, fat body, and cytochemistry of Diatraea flavipennella Box (Lepidoptera: Crambidae) hemocytes

Abstract

Nutritional and physiological interactions depend on the evolutionary history of the host-parasitoid interaction considering that the host’s regulation by the parasitoid is species-specific. Cotesia flavipes Cameron was introduced in Brazil in the 70’s to be used in the control of Diatraea sugarcane borer complex; however, Diatraea flavipennella Box is restricted to Brazil. Thus, this study investigated the possible nutritional changes in the hemolymph and fat body, and cytochemistry of D. flavipennella hemocytes parasitized by Cotesia flavipes. The levels of nutrients were quantified using colorimetric tests in the hemolymph and fat body. Levels of acidic polysaccharides, mucin, and lipids were investigated only in hemocytes using cytochemical techniques. In addition, histological sections of parasitized and non-parasitized caterpillars were prepared to observe volume changes and the presence of glycogen in the fat body. The results showed a reduction in protein and lipid concentration in the hemolymph of parasitized caterpillars. The parasitism reduced the levels of total carbohydrate, glycogen, and protein in the fat body and almost completely consumed the perivisceral fat body. It changed the cytochemistry of hemocytes and reduced acidic glycans in prohemocytes and oenocytoids, mucin in plasmatocytes and granulocytes, and lipids in adipohemocytes, granulocytes, and prohemocytes. We concluded that the presence of the parasitoid leads to different changes in D. flavipennella hemolymph and fat body and alters the cytochemistry of hemocytes causing a significant reduction in the reserve tissue. The results from this study contribute to consolidating the use of C. flavipes in biological control programs targeting D. flavipennella in sugarcane crops.