• Korean journal of applied entomology
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• v.29 no.2
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• pp.123-131
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• 1990

To elucidate the role of tow environmental factors, temperatures and photoperiod, in diapause induction and development of the dark grey cutworm, Agrotis tokionis B., field and laboratory experiments were implemented. As larvae entered diapause later, the diapause duration became shorter resulting in the synchronization of pupation of the test population. The summer diapause of this insect was assumed to be obligatory because every mature larvae had to experience summer dormant period at all experimental conditions of temperature and photoperiod. It was suggested that the diapause stage could be divided into two different phases in relation to temperature reaction. as the temperatures examined, the duration of diapause was shortened by higher temperature in the early phase, while it was shortened by lower temperature in the late phase. Th diapause period was the shortest under short-day condition (LD 8:16)

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.173-177
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• 1986

This study was carried out to see what makes the 'dark grey cutworm', Agrotis tokionis Butler, inflict less damage in P.E. film-mulched tobacco fields than in nonmulched ones. In field plot experiment, the damage ratio of tobacco seed lings in mulched plots(m) was reduced by 63% compared with that in non mulched ones(n). The altered environments did not affect the cutworm in mortality, which was confirmed by recovery ratio, location of larvae in soil, and developmental age. But the m/n value and damage ratio in plots of different mulching methods strongly suggest that the P.E. film itself prevent larvae from cutting the plants. Larval mortality was rapidly increased between the end of July and the end of August.

• Journal of Sericultural and Entomological Science
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• v.33 no.1
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• pp.27-31
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• 1991

Microsporidian spores were isolated from yellow-hind winged arctiid, Eilema griseola (Hubner), and cutworm, Agrotis tokionis Butler, and their morphological characteristics and their indectivity to silkworms were investigated. The shape of the microsporidian isolates was oval and the sige of the spore isolated from yellow-hind winged was measured in 2.6$\times$1, 5$\mu$ and that of the isolated from cutworm was measured in 3.7$\times$20.$\mu$. Both the isolated microsporidians showed the infectivity to silkworms, but the isolates did transovarian transmission in silkworms and the silkworm moth infected with the isolate from yellow-hind winged laid eggs irregularly.