ABSTRACT
Aim: The study aimed to develop and validate weather based prediction model for beet armyworm (Spodoptera exigua) population in chickpea through adult catches in pheromone traps. Methodology: The data on adult trap catches of S. exigua were recorded daily and weekly means were computed. Log transformed trap catches data were used for correlation with weather parameters of current week, 1-lag, 2-lag and 3-lag weeks. Thereafter, multiple-linear regression analysis was done and a model was developed. The prediction model of S. exigua was validated with the appropriate statistical tools. Results: Peak incidence of S. exigua was recorded during 45th standard meteorological week (SMW) with 15.6 moths per trap per week. Amongst current, 1-lag, 2-lag and 3-lag week weather parameters, the male moth population had significant positive correlation with maximum temperature (Tmax) and minimum temperature (Tmin), and negative correlation with morning relative humidity (RH1) of 2-lag week. The sunshine hours/day (SSH) of current week had a significant negative association with S. exigua male moth catches, while the soil temperature (ST) of 2-lag week had highest positive correlation with trap catches. Regression equation was computed by regressing male moth catches of S. exigua against weather data of weeks with highest correlation coefficient. Interpretation: Often, pest-weather models are developed based on current week weather factors. However, it has been witnessed in this study that weather of preceding weeks (up to 3-lag) may also influence the pest population, and thus it needs to be considered for proper understanding of pest dynamics
ABSTRACT
The beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) is difficult to control using chemical insecticides because of the development of insecticide resistance. Several pest control agents are used to control the beet armyworm. Entomopathogenic fungi are one of the candidates for eco-friendly pest control instead of chemical control agents. In this study, among various entomopathogenic fungal strains isolated from soil two isolates were selected as high virulence pathogens against larva of beet armyworm. Control efficacy of fungal conidia was influenced by conidia concentration, temperature, and relative humidity (RH). The isolates Metarhizium anisopliae FT83 showed 100% cumulative mortality against second instar larvae of S. exigua 3 days after treatment at 1 x 10(7) conidia/mL and Paecilomyces fumosoroseus FG340 caused 100% mortality 6 days after treatment at 1 x 10(4) conidia/mL. Both M. anisopliae FT83 and P. fumosoroseus FG340 effectively controlled the moth at 20~30degrees C. M. anisopliae FT83 was significantly affected mortality by RH: mortality was 86.7% at 85% RH and 13.4% at 45% RH. P. fumosoroseus FG340 showed high mortality as 90% at 45% RH and 100% at 75% RH 6 days after conidia treatments. These results suggest that P. fumosoroseus FG340 and M. anisopliae FT83 have high potential to develop as a biocontrol agent against the beet armyworm.
Subject(s)
Beta vulgaris , Fungi , Humidity , Insecticide Resistance , Insecticides , Larva , Metarhizium , Mortality , Moths , Paecilomyces , Pest Control , Soil , Spodoptera , Spores, Fungal , VirulenceABSTRACT
In this paper, the function of the iel gene from baculovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV), belonging to group Ⅱ nucleopolyhedrovirus, was studied in mammalian cells.We amplified the SeMNPV ie1 gene and expressed it by fusing to the C terminal of enhanced GFP protein in HEK 293 cells. Confocal microscopy revealed that the IE1-GFP fusion protein was localized in the nucleus of the mammalian cells. The promoter sequences of AcMNPV gp64, SeMNPV F protein and Drosophila hsp70 were also analyzed, to further study the function of SeMNPV IE1. The results showed that, in the absence of the hr sequence, IE1 improved the expression of the F promoter but didn't influence the gp64 promoter significantly, but IE1 moderately stimulated the hsp70 promoter.
ABSTRACT
By the breeding model of physics mutagenests (60Co,UV light) and re-strong in the body of insects, We obtained a Bt strain Bt99985 with high insecticidal activity. The shake flask and 40t tank fermentation tests showed that, this strain showed special activity against Spodoptera exjgua, Comparing with original Bt strain: 93005, CK strain: HD-1-580 and GC-91, the value of potency increased respectively by 429%, 655% and 114% in shake flask test. Comparing with GC-91, the value of potency increased by 180% in 40t tank fermentation test.
ABSTRACT
Specific primers 1CaA/1CaB for full cry1C gene in Bacillus thuringiensis subsp.colmeri strain 15A3 were designed. The 4.0kb PCR product included the whole ORF and regulation region of cry1C gene. This PCR product was linked with shuttle vector pHT315 by two cloning steps. The recombined plasmid pHT-1C was electroporated into Bacillus cereus 9509, a kind of bacteria that beneficial to crops. The transformant could produce bipyramidal-shaped parasporal inclusions. The 60kD protein band was detected by SDS-PAGE. The bioassay result showed that the cry1C gene transformant of Bc 9509 had insecticidal activity to Spodoptera exigua.