THERMAL REQUIRMENTS, BIOLOGICAL AND LIFE TABLE PARAMETERS OF Exochomus nigromaculatus (GOEZE) (Coleoptera: Coccinellidae) REARED ON THREE APHID SPECIES.

Document Type : Original Article

Authors

1 Economic Entomology Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, EGYPT

2 Plant Protection Research Institute, Agricultural Research Center, Ministry of Agriculture, Giza, Egypt.

Abstract

 
Developmental time and rate of immature stages, growth index, survival percentage, longevity, fecundity, and life table parameters of Exochomus nigromaculatus (Goeze) when reared on Aphis gossypii, Aphis craccivora, and Myzus persicae were studied at three constant temperatures (20, 24, and 28oC). The relationship between developmental rate of each stage and tested temperatures was also regressed.
There were significant variations in total developmental time of immature stages of the predator (male and female) among the three tested temperatures when the predators reared on the three studied preys.Meanwhile, there were no significant variations among the three aphid species at the same temperature. Growth index and developmental rate of E. nigromaculatus male were higher at 28oC than 20 and 24oC when reared on the tested aphid species. Survival percentage of immature stages when reared at 24 and 28oC was higher (100%) on M. persicae than on A. gossypii and A. crccivora (90%).  Exochomus nigromaculatus male and femalerequired 263.16 DD to complete their development from egg to adult male when reared on when it was reared on A. gossypii, A. craccivora, and M. persicae. There were no significant differences in pre-ovipositional period among the three tested temperatures. In addition, there were significant variations between inter-oviposition, oviposition, and total longevity when the predator was reared at the three tested temperatures. Male longevity was significantly shorter at 28oC than at 20oC and 24oC which fed on the same prey. Fecundity rate was significantly higher at 28oC than at 20oC and 24oC, when fed on the same prey. The mean generation time (T) and doubling time (DT) were shorter at 28oC than at 20oC and 24oC when fed on the same prey at 28oC. Generally, the value of gross reproductive rate (GRR), the net reproduction rate (Ro), the intrinsic rate of increase (rm), the finite rate of increase (λ) were higher at 28oC than at 20oC and 24oC.

Keywords

Journal of Plant Protection and Pathology
Volume 34, Issue 7
July 2009
Pages 8263-8282

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