Dispersion of flightless adults of the Asian lady beetle, Harmonia axyridis, in greenhouses containing cucumbers infested with the aphid Aphis gossypii: effect of the presence of conspecific larvae

Description

Most females of the Asian lady beetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), stop laying eggs if conspecific larvae are present. We studied the effect of this inhibition on the dispersion of this insect in a greenhouse containing cucumbers uniformly infested with the aphid Aphis gossypii Glover (Homoptera: Aphididae). In the absence of conspecific larvae, the adults moved around at random, sinuously, and independently. They spent most of their time walking on the ground and only a little time on the aphid-infested plants. When the cucumber plants in one half of the greenhouse had conspecific larvae on them, the whole adult population migrated to the larva-free half of the greenhouse. Consequently, most eggs were laid in that part of the greenhouse which was devoid of larvae. The consequences of this spatio-temporal interaction between larvae and adults for the biological control of aphids is discussed.

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