The sample sizes of some of the leaf-reared and parasitized diet-reared larvae were limited because * This paper (No. First stadium larvae were parasitized by exposure to Apanteles congregatus wasps over a 24-hr period after which time they were reared on a diet under the same conditions as unparasitized dietreared larvae. The hornworm diet was somewhat modified from that described by Yamamoto (1969), and the leaf diet consisted of field-grown burley tobacco. MATERIALS AND M E T H O D S Larvae were reared according to methods described by Dahlman (1969) under a 15L : 9D photoperiod. The objectives of the present investigation were to compare hemolymph trehalose and glucose levels of developing tobacco hornworm larvae as they were influenced by diet and parasitization. Preliminary studies showed greatly reduced levels of trehalose in the hemolympb_ of hornworms from which parasitoids had emerged (Dahlman, 1970). Fat body is a major site of trehalose synthesis (Wyatt, 1967), and cursory observations of larval fat body of tobacco hornworm, Manduca sexta, indicated reduced amounts in individuals parasitized by the braconid wasp, dpanteles congregatus (Dahlman, 1970). Wyatt (1967) reviewed papers describing the distribution and metabolism of trebalose in insects and cited examples of trehalose content being influenced by the diet. INTRODUCTION TREHALOSEis the most abundant free sugar found in insects and with few exceptions (Leader & Bedford, 1972) has been found in at least some stage in the life history of all species examined. Trehalose, but not glucose, levels were lower in diet-reared larvae parasitized by Apanteles congregatus than in unparasitized diet-reared larvae. Fourth stadium levels of trehalose were generally greater than fifth stadium levels. Levels of trehalose were higher in the earlier part of each stadium. Glucose and trehalose levels in the hemolymph were significantly lower in leaf-reared larvae. Tobacco hornworms, Manduca sexta, were reared on either tobacco leaves or synthetic diet. DAHLMAN Department of Entomology, University of Kentucky, Lexington, Kentucky 40506, U.S.A.
Printed In Great Britain TREHALOSE AND GLUCOSE LEVELS IN HEMOLYMPH OF DIET-REARED, TOBACCO LEAF-REARED A N D PARASITIZED TOBACCO HORNWORM LARVAE* D.
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