Thumbnail Image

Thesis

Browse

20151
Reset filters
Subject: Entomology × Author: Kaur, Arshdeep × End date: 2015 × Start date: 2015 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Phenotypic and genetic variability in Helicoverpa/Heliothis spp. in Punjab
    (PAU, 2015) Kaur, Arshdeep; Arora, Ramesh
    The studies on phenotypic and genetic variability in Helicoverpa armigera populations collected from different crops, viz. American (non-Bt) cotton, pigeon pea, Egyptian clover (berseem), sunflower and tomato, and different locations, viz. Ludhiana, Abohar and Gurdaspur were conducted during 2012-2013. The morphometric studies showed that larvae, male and female pupae and male and female adults belonging to different locations and collected from different host plants differed significantly with regard to weight and length. The cotton population recorded the maximum larval weight (532.36± 4.45 mg) while minimum was recorded in the sunflower population (402.07± 4.46 mg). Among locations, maximum larval weight was recorded in the Gurdaspur population (505.37± 3.82 mg) followed by the Ludhiana population (456.32± 3.78 mg). Minimum larval weight was recorded in the Abohar population (380.09± 4.91 mg). The male genitalic studies showed identical shape indicating that all the populations represent the same species, i.e. H. armigera, however, the populations differed significantly with regard to male genitalic morphometry. Inter-host and inter-location breeding studies on different populations of H. armigera revealed that all crosses were fertile. Maximum fecundity and per cent egg hatch was recorded in the cotton♂×pigeon pea♀ cross (384.90 eggs per female and 79.86%, respectively) and minimum fecundity was recorded in the cotton♂×sunflower♀ (172.20 eggs per female) pairing. Among the crosses of H. armigera populations collected from different locations, maximum fecundity and per cent egg hatch was recorded in Ludhiana♂×Gurdapur♀ pairing (272.20 eggs per female and 80.12%, respectively) and minimum in case of the Gurdaspur♂×Abohar♀ cross (64.25 eggs per female and 65.88%, respectively). The molecular characterization of H. armigera populations revealed that two clusters were formed based on RAPD-PCR in both inter-host and inter-location experiments. The nucleotide sequences of all the seven mt COI region variants of H. armigera were submitted to Boldsystems and Bold IDs were granted accordingly. Based on sequence analysis of mitochondrial cytochrome oxidase I gene, the Ludhiana population differed from Gurdaspur population by the 0.5 per cent and from Abohar population by 0.2 per cent while the latter two differed from each other by 0.7 per cent. Among populations infesting various host plants, the cotton population differed from sunflower by 0.2 per cent, Egyptian clover by 0.3 per cent and tomato and pigeon pea by 0.4 per cent. The study thus found little genetic variation based on alignment of DNA sequences based on mitochondrial cytochrome oxidase I region, supporting the idea that H. armigera represented a single species with no specialized sub-species. The beet armyworm Spodoptera exigua was recorded as a new pest on Egyptian clover.