Comparative Study on Reproductive Biological Characteristics of Helicoverpa Armigera and Helicoverpa Assulta (Lepidoptera:Nuctuidae)
|School||Henan Agricultural University|
|Course||Agricultural Entomology and Pest Control|
|Keywords||Helicoverpa armigera Helicoverpa assulta reproductive behavior internal genital organs total carbohydrate total protein cathepsin L gene cloning and prokaryotic expression|
Two sibling species Helicoverpa armigera(Hübner) and Helicoverpa assulta(Guenée)are serious crop pests in China. They have the similar morphological, biological and ecological characterstics,as well as they can even hybridize With each other. however, Their host plant ranges are largely different. The former is a typical polyhpagous species, and the latter is an oligophagous species with a narrower host plant range. In this paper, the behavioral, morphological, physiological, mechanism of H. armigera and H. assulta to their reproductive biological characteristics were studied comparatively, and the main results were summarized as follows:1. Reproductive behaviors of Helicoverpa armigera and H. assulta (Lepidoptera: Nuctuidae): (1) The mating capacities of female and male in two sibling species had no significant differences. The mating rates of two sibling species on the third-day adults were relatively high. Furthermore, The mating duration of H.assulta were longer compared with that of H.armigera. Mating duration gradually prolonged with the increase of the mating ages. The stage of daily mating activity of two sibling species were significant differences. (2) The preoviposition periods of H.armigera and H.assulta were 2.5 days and 3.6 days on 1-d-old adults respectively, the preoviposition periods of H.armigera were significantly shorter than H.assulta among different aged pairs. The premating periods of H.armigera were significantly longer than H.assulta among different aged pairs. The egg fertilities of H.armigera were significantly higher than that of H.assulta among different aged pairs .Both oviposition periods and fecundities were significant differences between the two sibling species. The fecundities of H.armigera were much more than that of H.assulta among different aged pairs.2. Internal genital organs of H.armigera and H.assulta: The morphologics of female and male internal genital organs of H.armigera and H.assulta on developmental stage were similar. The length of median oviduct, lateral oviduct and ovariole increased as developmental stage increased. The length of median oviduct, lateral oviduct and bursa copulatrix corpus of H.armigera were longer than H.assulta among different stages and there were significant differences. The length of ovariole and bursa copulatrix collum, the width of bursa copulatrix corpus of H.armigera were longer than H.assulta among different stages and there were no significant differences. However, The diameter of testes decreased as developmental stage increased, and The diameter of testes of H.armigera were significant longer than H.assulta among different stages.3. The content of total carbohydrate and protein in reproductive system of H.armigera and H.assulta: The content of total carbohydrate and protein in male reproductive system and male accessory gland of H.armigera and H.assulta were increased as developmental stage increased, and them of two sibling species were significant differences on developmental stage . The Content of total carbohydrate and protein in reproductive system after mating were significantly higher than before-mating, but them in male accessory gland were opposite. The Content of protein in female reproductive system of two unmated sibling species on 3-d-old were 94.30 and 81.89μg/mg, and them after mating were 135.96 and 112.24μg/mg increased by 1.44 and 1.37 fold. The content of total protein in female reproductive system of two sibling species were significant differences on developmental stage.4. Cloning and sequencing of cathepsin L gene from Helicoverpa assulta and its expression in Escherichia coli: The cathepsin L cDNA from ovary of Helicoverpa assulta was cloned by reverse transcription polymerase chain reaction (RT- PCR) and 3’ RACE. The results of cloning and sequencing showed that the full length of HassCL was 1383 bp (Genbank accession NO.JN017204), encoding 341 amino acid residues,and the N-terminus hydrophobic region was predicted containing16 amino acid residues within the HassCL displayed the characteristic features of a signal peptide. Thus the predicted mature weight (MW) is 36.2 kDa, and isoelectric point (IP)of 6.01. The HassCL without signal peptide was then constructed into the expression vector pGEX-4T-2 for over expression in prokaryotic cells. The SDS-PAGE and Western blot analysis showed that induced by IPTG,The HassCL was expressed in Escherichia coLi BL21, and its MW was found to be about 62kDa by checking with SDS-PAGE,nearly equal to the predicted result.