STUDIES ON PARASITIZATION POTENTIAL OF Encarsia formosa Gahan AGAINST GREENHOUSE WHITEFLY, Trialeurodes vaporariorum (Westwood)
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Date
2020-10
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NAUNI,UHF
Abstract
ABSTRACT
The present investigations entitled “ Studies on parasitization potential of Encarsia formosa Gahan
against greenhouse whitefly, Trialeurodes vaporariorum (Westwood)” was conducted during the year 20192020
at Dr. Y S Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh. The study
reveals that E. formosa parasitized all the nymphal instars of T. vaporariorum with highest parasitism (50%) and
total host kill (52%) with fourth instar whereas the parasitism and total host kill with third instar was 46 and 50
per cent, respectively. The host feeding was highest (28%) with first nymphal instars. The total developmental
period from egg to adult emergence, longevity and fecundity of the parasitoid with third nymphal instars were
18.8, 8.3 days and 27.78 eggs/ female, respectively and with fourth nymphal instars it was 16.2, 8.8 days and
29.93 eggs/ female, respectively. The adult longevity was highest (13.6 days) with 100 per cent honey solution
and lowest (2.5 days) with distilled water. The gross reproductive rate, net reproductive rate, innate capacity of
natural increase, true intrinsic rate of increase, true generation time, finite rate of increase, doubling time and
weekly multiplication rate with third nymphal instars were 27.78 females/ female, 26.71 females/ female,
0.1458, 0.1472 females/female/day, 22.32 days, 1.16 females/ day, 4.71 days, 2.80 times, respectively and with
fourth instar these values were 29.93 females/ female, 27.15 females/ female, 0.1581, 0.1596
females/female/day, 20.69 days, 1.17 females/ day, 4.34 days and 3.06 times, respectively.E. formosa exhibited
type II functional response with third nymphal instars on the bases of parasitism with handling time and attack
rate of 0.361h and 0.031 h-1, whereas with total host kill it was 0.575h and 0.037 h-1. Similarly this parasitoid
exhibited type II functional response on fourth nymphal instars with handling time of 0.629h and attack rate of
0.039 h-1 on the bases of parasitism and total host kill (handling time: 0.518h; attack rate: 0.044 h-1). Mutual
interference of parasitoid with third and fourth nymphal instars of greenhouse whitefly occurred (m= 0.166) and
(m= 0.285) among the searching parasitoids when their density increased from 2 to 8 females, respectively.
Both E. formosa and E. sophia multiparasitized and kill the host by feeding the host nymphs already parasitized
by the other parasitoid, however, parasitoids offered in combination to third and fourth nymphal instars resulted
higher parasitism (third instar: 42 %; fourth instar: 46%) and host feeding (third instar: 30%; fourth instar: 32%)
and E. formosa showed higher parasitism with third and fourth (46 and 50 per cent) instar as compared to E.
sophia (36 and 38 per cent). Thus, E. formosa proved an effective biocontrol agent for the management of
greenhouse whitefly. Hence, it can be utilized as a component of integrated pest management programme of
greenhouse whitefly, T. vaporariorum after evaluating under field conditions.