The myosuppressins represent a subfamily of the insect FMRFamide-related peptides that share the common C-terminal heptapeptide sequence Asp-His-Val-Phe-Leu-Arg-Phe-NH,,' and have been identified in diverse insect species including the cockroach Leucophaea maderae, locusts Schistocerca gregaria and Locusta migratoria, the fleshfly Neobelleria bullata, and the fruitfly Drosophila melanogaster. Members of this family affect insect muscles, being potent inhibitors of cardiac and visceral muscle in addition to having effects on skeletal muscle and salivary glands. A related peptide, named ManducaFLRFamide, was isolated from the hawkmoth Manduca sexta and demonstrates myostimulatory activity on dorsal longitudinal flight muscles.'The related sulfakinin insect peptide family shares the C-terminal octapeptide sequence Xaa-Asp-Tyr(S03H)-G1y-His-Met-Arg-Phe-NH2 (Xaa = Glu or Asp) that terminates in HMRFamide, rather than the FLRFamide of the myosuppressins. The sulfakinins also share sequence similarities with the vertebrate gastrin/ cholecystokinin (CCK) hormone family with a C-terminal gastrin octapeptide sequence of Glu-Ala-Tyr(S0,H)-G1y-Trp-Met-Arg-Phe-NH2. Unlike the myosuppressins, the sulfakinins stimulate contractions of the isolated cockroach hindgut, the original bioassay used to isolate t h e~n .~,~ In this study, we report that members of the myosuppressin and sulfakinin Corresponding author. 335 336 ANNALS NEW YORK ACADEMY OF SCIENCES 35 -7

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Protease, amylase, lipase and trehalase are present in the larval and adult mid guts of Oryctes rhinoceros; cellulase is absent. Invertase is present only in the adult. The presence of trehalase in the pupal midgut suggests that food digestion is not the normal function of gut trehalase. Quantitative studies reveal that protease and amylase in the third instar larvae reach very low levels as the larvae become older and consume little or no food. These two enzymes are not measurable in the non-feeding prepupa and pupa and reappear in the adult with commencement of feeding. Secretion of digestive enzymes is correlated with feeding.

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