Yoshiharu Matsumoto

Fungal volatiles as oviposition attractants for the yellow peach moth, Conogethes punctiferalis (Guenée) (Lepidoptera: Pyralidae)

Abstract Attraction and oviposition responses of the yellow peach moth to seven species of fungi were investigated in laboratory and field cages. The gravid moths were attracted to and oviposited on fruits of the codling, a host plant. The attractancy was removed from a fresh codling fruit by dipping it in ether, but higher attractancy reappeared subsequently when the fruit was inoculated with fungi. Similar attractancy was observed on a mouldy rice cake. By contrast, a rotten codling or rice cake, infected with bacteria rather than fungi inhibited oviposition by the moths. From the mouldy codling or rice cake, four fungi (Penicillium sp., Cladosporium sp., Aspergillus fumigatus and Mucor sp.) were isolated. When grown on Czapeks medium, the first two species showed the highest attractancy, while the last two species were less attractive. Among four phytopathogenic fungi tested, Endothia parasitica and Alternaria solani were also attractive. In a field cage, the moths oviposited significantly more on the oviposition substrates baited with Penicillium sp. than on a fresh codling or unbaited control.

Low-temperature tolerance of the vegetable weevil, Listroderes costirostris Schönherr (Coleoptera: Curculionidae).

The vegetable weevil, Listroderes costirostris SCHONHERR, hibernates in a non-diapause state in winter and can survive in northern Japan despite regional low temperatures. For these reasons, the low-temperature tolerance of larvae and adults was determined. The supercooling points of the adults and last-instar larvae were -9.0°C and -6.7°C, respectively. All adults and 50% of tested larvae could not tolerate -10°C for 3 hours. As air temperature decreases, adults and larvae move beneath the bottom leaves in contact with the ground surface or around the stalks where temperatures are higher than in aerial parts. Their behavior for avoiding freezing temperatures may enable them to survive winter in northern Japan, although their low-temperature tolerance is poor.