K. C. Sharma ¹, O. P. Bhalla ¹

Affiliations
1 Department of Entomology, Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan 173230, H.P., IN

Abstract

Life table studies on Eupeodes corollae (Fabricius), an important syrphid predator of the cabbage aphid, Brevicoryne brassicae (Linnaeus) in the mid-hill region of Himachal Pradesh revealed that the net reproductive rate (Ro) of the species was 187.52 female eggs/female. The true intrinsic rate of natural increase (r_m) was 0.134. The population multiplied 1.14 times per day during the generation and was able to multiply 2.55 times every week. On reaching a stable age-distribution, the population comprised approximately 97 per cent of immature stages.

Keywords

Brevicoryne brassicae, Eupeodes corollae, Intrinsic Rate of Increase, Life-Table, Net Reproductive Rate.

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A. K. Sood ¹, O. P. Bhalla ¹, K. C. Sharma ¹, Anil Kumar ¹

Affiliations
1 Department of Entomology, Dr. Y. S. P. University of Horticulture and Forestry, Nauni, Solan 173230, H.P., IN

Abstract

Studies conducted on the natural enemies of Pieris brassicae (Linnaeus) in the mid-hill region of Himachal Pradesh, revealed that mortality caused by hymenopteran parasitoids,  Cotesia glomeratus (Linnaeus) and Hypersota ebeninus Gravenhorst ranged between 3.9-23.6% with its peak during mid April, while the mortality due to bacterial pathogens viz., Bacillus sp. and Serratia marcescens Bizio varied between 1.2-23.7%. Predators like Episyrphus balteatus (de Geer), Coccinella septempunctata Linnaeus and Polistes hebreus (Fabricius) though active, their role in suppressing the population of P. brassicac was negligible. The role of meteorological factors in the dynamics of natural enemies is also discussed.

Keywords

Abiotic Factor, Parasitoids, Pathogens, Pieris brassicae, Predators, Seasonal Activity.

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K. C. Sharma ¹, O. P. Bhalla ¹, Usha Chauhan ¹

Affiliations
1 Department of Entomology, Dr. Y.S. Parmar University of Horticulture and Forestry, Solan - 173 230 H.P., IN

Abstract

Syrphids have been recognised as important predators of aphids (Ghorpade, 1981; Agarwala et al., 1984). In the mid-hill regions of Himachal Pradesh Eupeodes frequens Matsmura has been found to predate upon Brevicoryne brassicae (L.) (Aphididae, Homoptera) infesting cauliflower. The present study was undertaken to study the life-table and intrinsic rate of increase of E.frequens under laboratory conditions to understand the dynamics of this predator as biological agent of the aphid.

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