Behavioural response of Chilocorus bipustulatus (Coleoptera: Coccinellidae) to variation in Unaspis eunymi (Homoptera: Diaspididae) density at spatial scales

Abstract :

The behavioral response of Chilocorus bipustulatus L. to variation in eunymus scale, Unaspis eunymi Comstock density at different patches was examined under laboratory conditions (27 ± 2°C, 70 ± 5 % of RH, 16L: 8D). Different densities of eunymus female scales were set on Eunymus japonicus leaves under a stereomicroscope and were placed in plastic containers. Plastic containers were arranged randomly equidistant from one another in the cage. The experimental procedure involved introducing different number of female predator separately in the center of the cage. The patterns of percentage of time spent on each patch, revealed a tendency for aggregation on the patches of high prey densities. Predators spent proportionately more time on high density patches than on low ones. The proportion of predators found in each patch also indicated aggregation of predators in high density patches. The values of aggregation index for 1 to 16 female predators were all greater than zero showing the concentration of the predator in patches with high prey densities. The percentage of prey eaten was variable in different prey patch densities, showing a density dependence tendency. It was found in this reseach that Chilocorus bipustulatus aggregated in high density patches of its prey, but the pattern of predation, was variable at different patch densities of the prey. Density dependent pattern of predation has been shown to suppress pest population and even contribute to population stability.

Keyword :

Aggregation, density dependent, Chilocorus bipustulatus, Unaspis eunymi

Author(s) : Jaihoni, M., Sahragard, A., Salehi, L.
Downloads : 2880
Published Issue : 2008 Vol. 3 Number 2

2008 Vol. 3 Number 2