Geographic variation in morphometry genetics and insecticide resistance in cotton bollworm helicoverpa arllligem hubner populations occuring in south indian cotton ecosystems and validation of IPM and IRM modules

Abstract

Phenotyping for various morphometric traits at larval, pupal and adult stages of newlineHelicoverpa armigera (Hubner) revealed significant variation between the populations form newlinetwelve different geographic locations of south Indian cotton ecosystem. Study on the newlinerelationship between larval resistance to different insecticides and morphometry of H. newlinearmigera population revealed positive and significant relationship in most of the cases with newlinesome exceptions. Insecticide bioassay of F1 generations for most widely used conventional newlineinsecticides clearly indicated that resistance to synthetic pyrethroid (cypermethrin) is newlineprevalent in all most all the study locations highest being Raichur of Karnataka and Guntur of newlineAndhra Pradesh. Overall populations form northern part of south India comprising Andhra newlinePradesh and Maharashtra and Raichur of Karnataka found to posses significantly higher newlinephenotypic attributes for all the quantitative morphometric traits and hgher level of newlineinsecticide resistance than those from Southern states (Tamil Nadu and part of Karnataka). newlineGenetic similarities among geographical population from the mitochondrial marker data were newlinewithin the similarity coefficients ranging form 0.13 to 0.52, indicating high level, of genetic newlinedifferences between population. On the basis of simple matching coefficients all the selected newlinepopulations were grouped into 4 clusters. Cluster 2 is having maximum of five populations newlinefollowed by cluster 1 with four populations, cluster 4 with two and cluster 3 with single newlinepopulation. None of the populations compared to one another beyond a similarity coefficient newlineequivalent to 0.52. Field validation of IPM and R-IPM modules based on genetic diversity at newlineMaradagi village, yielded maximum yield of 16.00 q ha-1 from IPM module at Maradagi newlinevillage followed by 13.80 q ha-1 in R-IPM module. On the contrary, farmers check plot newlinerecorded a lowest seed cotton yield of 11.15 q ha-1. IRM module at Eklaspur village of newlineRaichur recorded a highest seed cotton yield of 15.30 q ha-1 compared to 10.88 q ha-1