Spatial Distribution and Interaction of Eriosoma lanigerum and Aphelinus mali on Apple Under Dry-Temperate Conditions of India

Abstract

Knowledge of the seasonal abundance and type of spatial distribution of any insect pest is the prerequisite to formulate a reliable sampling programme for that species. Apple woolly aphid, Erosoma lanigerum (Hausmann) (Hemiptera: Aphididae), is one of the most important insect pests of apple throughout the world. The present study was aimed to study the seasonal abundance and spatial distribution of this pest and its specialist parasitoid, Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) under dry temperate conditions of Himachal Pradesh, India during 2013 and 2014. Various dispersion indices were calculated to determine the type of spatial distribution and optimum number of samples. E. lanigerum assumed activity in the month of June and remained active till December by following negative binomial distribution during both the years. The aphelinid parasitoid acted in a density dependent manner by coinciding well with its host and also followed negative binomial distribution except at very low densities. Optimum number of samples required for the aphid and the parasitoid varied with the mean density and the desired precision level.