The comparative Effect of Hormone Mimics, Moulting Inhibitors, and Orthodox Insecticides on the Metamorphoses of Lucia cuprina (Wied) and Musca domestica (Linn.) (Dipteria Cyclorrhapha)
MOSES O.E. IWUALA
ABSTRACT: In a comparative study of the relative values of hormone analogues, synthetic moulting.; inhibitors, and some orthodox insecticides for the control of myiais producing insects, nine different compounds have been assayed against the egg, pupae and adults of susceptible and resistant strains of Lucilia cuprina (Wied) and Musca domestica (Linn.): Beside causing general delay of the insects’ metamorphosis, juvenile hormone (JH) analogue, were found to be strongly ovicidal and reasonably active against the 1st instar larvae. They were less toxic to the 2nd and 3rd instars, were found to interfere with larva-pupa transformation, and caused delayed mortality of the flies within puparia. Moulting hormone (MH), on the other hand, caused accelerated development (and moults), and was rather non-toxic to the larvae and pupae. The noulting inhibitors (PH 60-40, PH 60-38 and MON 0585) showed effects similar to those of the JH analogues although they are structurally unrelated to the latter. The two orthodox insecticides (gamma BHC and diazinon) showed acute toxicity to the different stages of insects, but did not, at sub-lethal concentrations, affect speed of development of the eggs, larvae or pupae . Organophosphorus resistant strains of L. cuprina and M, domestica were cross resistance to one of the JH analogues tested, but organochlorine resistant strains were not cross-resistant. Potential values of the hormone analogues, moulting inhibitors, and orthodox insecticides for fly control are discussed in terms of their relative potencies and their possible involvement in resistance. Also plausible explanations are adduced for the differences in modes of action of the various compounds.