Evidence for population expansion of Cotton pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) in India

Abstract

pink bollworm, Pectinophora gossypiella (Saunders) infestation on Bt cotton is a major concern to cotton production in india. the genetic diversity and phylogeographic structure of the insect in light of PBW resistance needs to be revisited. The objective of this study was to identify different haplotypes of pink bollworm and their distribution in India. To achieve this we studied the population structure in 44 cotton growing districts of India. The partial mitochondrial COI sequence analyses of 214 pink bollworm populations collected from 44 geographical locations representing 9 cotton growing states of India were analysed. Genetic diversity analysis exhibited presence of 27 haplotypes, among them Pg_H1 and Pg_H2 were the most common and were present in 143 and 32 populations, respectively. Distributions of pairwise differences obtained with partial COI gene data from the overall Indian populations are unimodal, suggesting population expansion in India. Significant neutrality test on the basis of Tajima' D and Fu's Fs presented a star-shaped haplotype network together with multiple haplotypes. The unimodal mismatch distribution, rejection of neutrality test with significant negative values supported the theory of demographic expansion in cotton pink bollworm populations in india. Genetic data not only provides us with a perspective of population genetics, but also that the two populations of pink bollworm, those occurring early in the season are genetically close to the late season populations with respect to their partial CO1 region. Resistance to Cry toxins does not seem to have had an impact on this region of the mt DNA in populations of pink bollworm.Cotton is one of world's most essential fiber crops having global significance, cultivated in tropical and subtropical regions of more than 70 countries 1,2 . In India, cotton is mainly cultivated in three distinct agro-ecological zones (North, Central and South) 3,4 . Cotton is cultivated on an area of 12.43 million ha with average productivity of 505.46 kg/ha in India during 2017-18 5 . Several biotic and abiotic stresses are constraints in cotton production including the bollworm complex and sucking pests 6 . Among the bollworm complex, pink bollworm (PBW), is one of the major damaging insect pests of cotton with an extensive range across India leading to severe loss to cotton production 7,8 .Pink bollworm has become apparent as a threat to cotton cultivation in south and central cotton growing zones of India where the pest has developed resistance to Cry1Ac and Cry2Ab expressing cotton also developing resistance to insecticides and infesting late season cotton 8,9 . The PBW is assuming a major pest status even in some regions of northern India where there are ginning and oil extraction units which are procuring cotton seeds from central and south Indian cotton states where PBW has demonstrated resistance to Cry toxins in the field. So there is possibility of resistant pink bollworm infesting Bt cotton in North India through movement of seed. The evolution of...

Assessing Genetic Diversity of Three Species of Potato Tuber Moths (Gelechiidae, Lepidoptera) in the Ecuadorian Highlands

“…Overall, low genetic diversity of P. gossypiella population was attributed to invasion bottlenecks (Liu et al 2010). The haplotype prevalence in both S. tangolias and P. operculella in our study were similar to what was described in Liu et al (2010) and Naik et al (2020), and that was the presence of 1 dominant haplotype along with multiple less common haplotypes. It is possible that these 2 species underwent population expansion, rapid growth from a small-sized founder population (Grapputo et al 2005;Saw et al 2006).…”

“…Many lepidopteran pests are highly mobile and have a great propensity to invade new agricultural regions. Using COI genetic marker, Naik et al (2020) found 2 common haplotypes of cotton pink ballworms, Pectinophora gossypiella Saunders (Lepidoptera: Gelechiidae), across cotton-growing regions of India. The star-shaped haplotype network, with the most common haplotype at the center surrounded by rare haplotypes with a few mutational steps, suggested a recent population expansion of this Gelechiidae moth.…”

“…Examples are the observed differences in host preference by 2 fall armyworm strains (Pashley 1986) and the presence of allochronic populations of processionary moth (Santos et al 2013;Leblois et al 2018). There were only a handful of studies that examined genetic diversity and variation of Gelechiidae (Liu et al 2010;Medina et al 2010;Torres-Leguizamón et al 2011;Naik et al 2020). It is in our future interest to test whether haplotypes of each potato tuber moth species show differences in host preference, behavior, and life-history traits.…”

Comparative Genetic Analysis of Invasive Fall Armyworm Populations Provides Evidence for Population Expansion in India

“…(http://mowr.gov.in/agro-climatic-zones), which is partly responsible for the observed diversity in India. Previous studies on intra-species diversity of certain insect pests in India have suggested geographical sub-structuring within different regions of India [26][27][28]. We looked at the distribution of the different haplotypes in India but most of the novel haplotypes in India at present are too infrequent and dispersed to attribute them to speci c ecozones of India.…”

Fertilizers, BT technology, and insecticides contributed to 60%, 23%, and 17%, respectively to the increase in BT cotton yield: An analysis from 2000 to 2014 in India

“…Thus, Bt cotton can be considered as the major technological achievement which has been benefiting more than 6 million farmers in India. However, high incidence of pink boll worm was recently reported in Bt cotton field in India (Naik et al, 2020;Mahesh and Mohan, 2020). In this regard, approaches such as releasing sterile moths, and planting of cotton hybrids developed through the cross between Bt and non-Bt cotton can be employed for the management of Cry genes resistant bollworms (Wan et al, 2017;Tabashnik and Carriere, 2019).…”