Laboratory observations on the ability of Ephestia cautella (Walker) (Lepidoptera: Phycitidae) to locate,and to oviposit in response to a source of grain odour

Grain odour influenced oviposition behaviour was investigated amongst free-flying, gravid Ephestia cautella females. Females released into a 5 m³ or 10 m³ cage readily located, and oviposited in the vicinity of, small sources of diffusing grain odour or grain odour in an airstream. Oviposition increased at the odour source when 30% of an airstream carrying grain odour was replaced by CO₂, whereas it decreased when 95% was replaced by N₂, and did not change when 60% was replaced by either CO₂ or N₂. Females released into a wind-runnel responded to grain odour by increased frequency of upwind flight and by landing at the odour source. These responses are discussed in the context of grain stores sealed for treatment with controlled atmospheres or fumigants.