Makoto Hatakoshi

An inhibitory mechanism over oviposition in the tobacco cutworm, Spodoptera litura by juvenile hormone analogue pyriproxyfen

Abstract The effects of a juvenile hormone analogue, pyriproxyfen, on the reproduction of tobacco cutworm, Spodoptera litura, were examined. Topical application of 0.3 ng to day-0 female pupae reduced the number of eggs oviposited. Ovarian development and egg maturation in pyriproxyfen-treated moths were normal in most females. The reduction in eggs oviposited was due to the lack of an oviposition stimulating factor which was present in female haemolymph but not in male haemolymph. A lower activity of the factor was present in virgin females and pyriproxyfen-treated females. Precipitation with ammonium sulphate, heat treatment, dialysis and protease treatment showed that the factor is a protein and its molecular weight is more than 14 kDa.

Hormonal control of cuticular melanization in the common cutworm, Spodoptera litura

Abstract The penultimate-instar larvae of Spodoptera litura raised under crowded conditions deposited melanized cuticle, which could be labelled by injected [ 14 C]dopamine, while those reared in isolation deposited non-melanized cuticle. In crowded culture, melanization-and-reddish-colouration hormone was secreted between 6 and 9 h after head-capsule slippage, followed by melanization about 4 h later. Extirpation of the suboesophageal ganglion from the crowded larvae totally blocked melanization, while removal of the brain allowed 50% of the melanization as after denervation between the two organs. This suggests that the melanization-and-reddish-colouration hormone is secreted from the suboesophageal ganglion, and the brain regulates its secretion from that organ. Injection of melanization-and-reddish-colouration hormone of Bombyx mori into an isolated abdomen induced melanization, while this treatment combined with methoprene blocked it. Application of methoprene to crowded larvae up to 2 h before head-capsule slippage greatly reduced the black pigmentation. Allatectomy of the larvae reared in isolation could induce full melanization. These results indicate that a decrease in juvenile hormone titre at around the time of head-capsule slippage is essential for exhibiting the action of melanization-and-reddish-colouration hormone.

Antifeedant and Insecticidal Activity of Quassinoids against Diamondback Moth (Plutella xylostella)

The antifeedant and insecticidal activities of sixteen quassinoids against 3rd instar larvae of the diamondback moth (Plutella xylostella) were compared with those of known insect antifeedant chlordimeform (1), and the structure-activity relationship was discussed. The insecticidal activity of quassin (2) was higher than that of 1, although its antifeedant activity was nearly the same as that of the reference compound.

New Trifluoromethanesulfonanilide Compounds Having High Miticidal Activity against House Dust Mites

Several 2-alkoxycarbonyltrifluoromethanesulfonanilides were prepared to examine their miticidal activity. 4-Halo-2-alkoxycarbonyltrifluoromethanesulfonanilides in particular showed good miticidal activity against Tyrophagus putrescentiae (Tp), Dermatophagoides farinae (Dp) and Chelacaropsis moorei (Cm). Amidoflumet (methyl 5-chloro-2-[(trifluoromethyl)sulfonyl]aminobenzoate) was selected and has been developed as a new miticide for house dust mites.

CYCLOPROPANEGARBOXYLATE WITH FOUR SUBSTITUENTS ON THE CYCLOPROPANE RING, A POTENT PYRETHROID

Novel spiro-fused cyclopropanecarboxylic acids have been prepared. One of esters derived from these acids and α-cyano-3-phenoxybenzyl alcohol was more active to housefly than fenpropathrin and cypermethrin. Synthesis of these acids and activities of the esters derived from the acids against various insects are presented.