Ecological and control studies of the cotton aphids, Aphis gossypii (Glover.) on eggplant, Solanum melongena L.

Abstract

The present study was conducted to estimate the distribution of apterous and alates cotton aphids within and between plants. Also, population dynamic of cotton aphid and its predators, and the effects of foliar spray with elicitors viz, salicylic acids (SA), jasmonic acids (JA) and β-aminobutyric acid (BABA) on the population density of A. gossypii were estimated. The experiments were carried out in an eggplant field at Nobaria district, El-Beheira Governorate, Egypt. The results of spatial distribution of apterous A. gossypii by using the diffusion coefficient (S2/ m) was >1, by using David-Moore index (IDM) was positive value for negative binomial, by using patch index (m*/m) was >1 and with using Cassie index (Ca)was>0 and positive values. All these indices are indicative of aggregation (the individuals tend to occur in clumps) distribution model for the apterous A. gossypii in all the sampling dates throughout the two successive seasons 2019 and 2020. On contrary, all of these indices refer to a uniform spatial distribution for the alates A. gossypii., there were proportionally greater numbers of the alates individuals on the middle part of eggplants. The results also showed that the seasonal mean population of cotton aphids was higher during 1st season than during the 2nd season The apterous aphid populations were significantly higher within the upper level than other levels of the plant. The foliar spray of JA, SA and BABA resulted in decreasing the cotton aphid population density in eggplant crop. SA proved to be less efficacious than JA and BABA.