Effects of Novaluron and Cyromazine, chitin synthesis inhibitors, on the larval hemogram of Spodoptera littoralis (Boisd.)(Lepidoptera: Noctuidae).

Manuscript History: The present study was carried out aiming to investigate the effect of two chitin synthesis inhibitors (CSIs), Novaluron and Cyromazine, on the larval hemogram of S. littoralis. Five main types of circulating hemocytes, viz., Prohemocytes (PRs), Plasmatocytes (PLs), Granulocytes (GRs), Spherulocytes (SPs) and Oenocytoides (OEs), had been identified in last instar (6 th ) larvae. The most important diagnostic characteristics of each type were described. After treatment of the newly moulted penultimate instar larvae with LC50 of Novaluron or Cyromazine, the successfully moulted last instar larvae were used to investigate the most important hematological responses. Novaluron remarkably enhanced the production of hemocytes at two limits of larval instar. On the other hand, Cyromazine exerted an inhibitory action on THC during the majority of larval instar, with few exceptions. Novaluron treatment resulted in slightly increasing PRs and PLs during the first half of instar but slightly decreasing during the second half. GRs were prohibited but SPs had been enhanced by Novaluron along most larval duration, with few exceptions. Cyromazine exerted a prominent prohibiting action on PRs and GRs but remarkably stimulated PLs along the larval life. Cyromazine exhibited contradictory effects on SPs, depending on the larval age. During the second half of larval instar, OEs were enhanced by both CSIs. The present CSIs exhibited some destructive cytopathological effects on all hemocyte types, morphologically and intercellulary, except Cyromazine against OEs.