Consequences of parasitized aphid prey feeding on the development and fitness attributes of predatory syrphid, Ischiodon scutellaris (Fabricius)

Abstract

A study was conducted to investigate the development and fitness of predatory syrphid, Ischiodon scutellaris on cowpea aphid host parasitised by Lysiphlebus fabarum. Number of eggs laid by I. scutellaris in the cowpea plants infested with healthy aphids (317.16 ± 14.84 eggs) and in plants with mixed population of healthy and parasitised aphids (302.20 ± 5.49 eggs) were statistically on par with each other. The number of healthy aphids (243 ± 36.65 aphids) and mixed population of healthy and parasitised aphids (206.60 ± 37.39 aphids) consumed by I. scutellaris was statistically on par with each other. Net reproductive rate (R₀) of I. scutellaris in the healthy and healthy + mummified aphid hosts were 289.90 ± 7.66 and 267.40 ± 2.74, respectively. The intrinsic rate of increase (r) of I. scutellaris on the healthy (0.15 ± 0.08) and healthy + mummified aphid hosts (0.14 ± 0.07) was significantly different from each other. The results of the study confirmed that adult flies of I. scutellaris could be maintained in the mixed population of healthy and mummified aphid host, A. craccivora without any interference in its oviposition and egg hatchability. The observations of this study are of practical significance in terms of culture maintenance of syrphid predator, I. scutellaris at times of non-availability of pure healthy aphid hosts.