Influence of Genetically Manipulated Brassica Genotypes on Parasitism Capacity of Diadegma semiclausum Parasitizing Plutella xylostella

Abstract

Plant quality in herbivores’ diet may affect the pe rformance of both herbivore and its parasitoids. In the present research, parasitism ca pacity of Diadegma semiclausum (Hellen) on Plutella xylostella (L.) reared on different genetically manipulated Brassica plants including the canola’s progenitor ( Brassica rapa L.), two cultivated canola cultivars (Cultivar-Oper a and Cultivar-RGS 003 ), one hybrid (Hybrid-Hyula 401 ), one gamma mutated (Mutant-RGS 003 ), and one transgenic (Transgenic-PF) genotype was determi ned. All experiments were carried out in a growth chamber at 25±1 ̊C, 65±5% RH, and a photope riod of 16:8 (L: D) hour. The value of the net parasitism rate ( C 0 ) of D. semiclausum was 14.94, 20.12, 14.95, 12.20, 13.94, and 12.55 hosts on B. rapa , Cultivar-Opera, Cultivar-RGS 003 , Hybrid-Hyula 401 , Mutant-RGS 003 , and Transgenic-PF, respectively. The transformation rat e from host population to parasitoid offspring ( Q p ) on all genotypes was close to 1 ( C 0 ≅ R 0 ). Moreover, the value of the finite parasitism rate ( ) was 0.271, 0.285, 0.277, 0.202, 0.205, and 0.202 ho st parasitoid -1 day -1 on the above-mentioned genotypes, respectively. The fi nite parasitism rate considers the finite rate of increase, the stable age-stage distribution, and the age-stage specific parasitism rate; therefore, this parameter could be used to assess t he efficiency of a parasitoid. In conclusion, D. semiclausum had higher parasitism capacity on canola’s progenit or and the cultivated genotypes which were more suitable for parasitoid’s host based on secondary metabolites concentration. Keywords : Diamondback moth, Finite parasitism rate, Manipul ated canola, Plant chemistry, Two- sex parasitism.