Influence of The Different Onion Varieties on the Population Density of the Main Insect Pests Infesting Onion Crop in Kafr El-Shekh Region.

Abstract

The current experiments were carried out in the Research Farm of the Agricultural Research Station in Sakha, Kafr El Sheikh Governorate, where three main onion varieties (Giza 6, Giza 20 and Giza Red) were cultivated, during 2013/14 and 2014/15 seasons, to study the influence of different onion varieties on the population density of the most important insect pests. The highest populations of all investigated insects were recorded on variety Giza 6 followed by Giza 20 and Giza Red during the two-successive season. This study showed that the highest average numbers of the onion thrips Thrips tabaci Lind. on Giza 6 were 316.6 ± 36.6 and 286.4± 34.1 nymphs during the first and second season, respectively. The highest average number of the onion aphid Aphis gossypii Glov was also recorded on Giza 6 and represented by 1124 ± 22.4 and 1061± 18.7 individuals, during the first and second season, respectively. The highest average numbers of the Onion maggot Dalia allairia Fonseca was also recorded on Giza 6 and represented by 37.7 ±7.6 and 41.3 ±8.5 during the first and secon season, respectively. The onion varieties showed significant differences in their attraction to T. tabaci and A. gossypii, but not for D.allairia. For the Integrated Pest Management strategy for onion crop, Giza 6 has to be excluded from the approach of crop breeders and farmers due to its higher susceptibility for infestation.