a study of the population dynamics of nipaecoccus viridis newstead in shiraz region: effective factors on population decrease

the spherical mealybug (nipaecoccus viridis newsted) is one of the most harmful pest of citrus, oleander and mulberry in green space of shiraz region. this study was carried out to detect the population dynamics of this pest and the role of biotic and abiotic factors on it in 2007-2008. the spherical mealybug, in both years, started its activity from early may on citrus and oleander trees, but the first sign of its infection on mulberry was detected in early august in most regions. the first population peak of mealybug occurred in the mid-june,َََthough its population decreased in august because of high temperature, and increased under  suitable weather condition when the second peak appeared in mid september. the negative effect of ants on natural enemies’ activity, especially during the egg-laying time, was determined. among the abiotic factors, pruning and pesticide application through the mealybug activity period had the most influence on the pest population dynamics.