Morph and Age Structure of Pea Aphid, Acyrthosiphon pisum (Hemiptera: Aphididae) in Lentil

Abstract

The study was conducted for three consecutive years (2011/12 to 2013/14) at Debre Zeit and Chefe Donsa to generate information on the morph and age structure o f pea aphid population in lentil. The data were generated from pea aphid management trial on two lentil genotypes Alemaya and ILL7664. There were 12 plots per genotype and from each plot aphid sample was collected by beating the plant three times onto a counting board of 20cm x 39cm. Aphids dropped on the counting board were put in a labeled plastic bag, brought to laboratory and separated in to alate, adult apterae and nymphs. Morph and age composition were not affected
by lentil genotypes. Thus, the pattern of morph and age structure was similar on both genotypes in any one year and location. At Debre Zeit, depending on season and sampling date pea aphid population was composed of 0.0 to 10.0% alate, 6.6 to 34.4% adult apterae and 62.3 to 92.7% nymphs. The corresponding values for ILL7664 were 0.3 to 14.8%, 3.7 to 29.3%, and 68.9 to 92.9%. Similarly, at Chefe Donsa out of the total pea aphid population on Alemaya 0.0 to 10.2% were alate, 8.3 to 38.1% were adult apterae and 57.1 to 88.9% were nymphs. On ILL7664 the population constituted of 0.0 to 11.2% alate, 9.1 to 37.0% adult apterae and 59.3 to 89.9% nymphs. The presence o f larger proportion of nymph indicates either the population is at an increasing rate or the survival rate i.e. the number of nymphs reaching adult stage is low. Therefore, the generated information will enable to understand the population dynamics of pea aphid and helps to develop effective integrated pest management program.