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Insecticidal effect on a population of S pilarctia obliqua ( L epidoptera: A rctiidae)
Author(s) -
Ansari M. Shafiq,
Ali Haidar,
Shafqat Shazia
Publication year - 2012
Publication title -
entomological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 20
eISSN - 1748-5967
pISSN - 1738-2297
DOI - 10.1111/j.1748-5967.2012.00478.x
Subject(s) - dichlorvos , biology , fecundity , endosulfan , imidacloprid , toxicology , hatching , population , lepidoptera genitalia , zoology , instar , population dynamics , larva , pesticide , botany , agronomy , medicine , environmental health
Survivors of S pilarctia obliqua derived from 3 rd instars that had ingested LC 50 of imidacloprid (0.025%), dichlorvos (0.014%) and endosulfan (0.012%) were studied through the life table method. Survivorship was reduced in insecticide exposed populations as compared to 45‐day in the control groups. Egg hatching was significantly decreased for the insecticide treated populations. Total larval mortality was the highest for endosulfan (36.76%) as compared to the individuals that died among control groups (14.29%). Life expectancy (e x ) was decreased gradually over time and stage of development for insecticides tested and the control groups. Dichlorvos (0.014%) has caused a significant reduction in the potential fecundity i.e. 315 females/female/generation, while 415 in the unexposed cohorts. Net reproductive rate ( R o ) was the lowest in endosulfan (118.47 females/female/generation) treatment followed by dichlorvos (141.97), imidacloprid (144.49) and the control groups (272.42). Similarly, the intrinsic rate of increase (r m ) was substantially decreased after exposure with endosulfan (0.124 females/female/day) as compared to 0.135 in the unexposed cohort. The finite rate of increase (λ) was not significantly different among the insecticide treatments and control groups. Mean generation time was significantly reduced after exposure to dichlorvos (37.19 days). However, 41.34 days were required to complete one generation by S . obliqua in the absence of insecticides. Based on these results, population of S . obliqua would double in 5.19 days under the influence of dichlorvos while requiring 5.13 days for unexposed cohorts.