Comparing the Effect of Selected Cabbage Varieties on the Fitness of Diadegma insulare Cresson Parasitizing Plutella xylostella Linnaeus under Controlled Conditions
Comparing the Effect of Selected Cabbage Varieties on the Fitness of Diadegma insulare Cresson Parasitizing Plutella xylostella Linnaeus under Controlled Conditions
Riaz Hussain1*, Ata-ul-Mohsin1, M. Farooq Nasir1, Zahid Akram2, Muhammad Sajid Qureshi1 and Abdul Mannan Hamzah1
ABSTRACT
Plutella xylostella (Plutellidae: Lepidoptera) is the one of most destructive and critical cosmopolitan insect herbivores of brassica crops. Globally efforts have been undertaken to develop integrated management strategies for its control, based principally on manipulation of its parasitoids including Diadegma insulare. The research study was conducted to investigate the effects of two cabbage varieties on fitness parameters (i.e. percent parasitism, offspring sex ratio and developmental periods) of Diadegma insulare, a larval parasitoid of Plutella xylostella. All experiments were carried out under controlled conditions maintained at 23±2 ºC, 60±5% RH and 16L: 8D photoperiod. The findings revealed that developmental period was lower on Asha while higher on Golden acre whenever both second and third instars larvae were released on cabbage varieties. Parasitism efficacy was lower on third instars larvae as compared to the second. Higher parasitism (53.53%) was assessed on Asha while lower parasitism (44.95%) was observed on Golden acre when second instars larvae were exposed. Parasitism was higher (61.17%) on Asha while lower (50.1%) on golden acre when third instars larvae were exposed. Offspring sex ratio differed on stages of parasitized larvae. Higher male offspring emerged when second instars larvae were parasitized while more female offspring were emerged when third instars larvae were parasitized by D. insulare reared on both varieties. It was concluded that Asha was recognized as most suitable variety, as developmental period of D. insulare was shorter as well as parasitizing efficacy was also recorded higher on Asha.
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