Efforts were carried out to isolate vegetative insecticidal protein genes from local isolates of Bacillus thuringiensis. The study focused on vip1/vip2 binary toxin, considering its insecticidal potential against coleopteran and hemipteran pests. Thirty nine B. thuringiensis local strains and one standard reference strain (HD 1) were screened for the presence of vip1/vip2 gene by using a PCR approach. Among 39 isolates only four isolates (PDKV-08, PDKV-27, PDKV-28 and NCIM-5112) showed the presence of the desired gene. SDS-PAGE screened profiling of the isolates showed the presence of 95 kDa and 50 kDa protein which confirmed our PCR study. For further characterization, the vip1/vip2 gene was cloned from the PDKV-08 isolate by using the pJET1 cloning vector. Sequence homologous analysis confirms the presence of the vip1/vip2 gene. A further BLAST analysis also revealed that the isolated vip1/vip2 gene is highly conserved and showed a maximum of 88% sequence homology with existing vip1/vip2 genes. Insect toxicological potential was also elucidated by performing bioassays of PDKV-08 supernatant proteins against the coleopteran store grain pest, Sitophilus zeamais. The results from a bioassay revealed 60% mortality.

Infection of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), with 'Candidatus' Liberibacter asiaticus (Las), the causal pathogen of citrus greening disease or huanglongbing, increases psyllid susceptibility to insecticides. Diaphorina citri populations in citrus occur year-round in tropical and sub-tropical habitats, and thus insecticide applications for managing this plant disease vector occur over a wide temperature range (10-40 °C). During the winter season, D. citri is occasionally exposed to periods of freezing temperatures, when temperatures fall below −6.5 °C. In this investigation, we compared insecticide susceptibility of uninfected and Las-infected D. citri at various temperatures (20-37 °C). Cold-acclimated (6 ± 1 °C) D. citri adults were less susceptible to neonicotinoid insecticides as compared with non-acclimated controls, but this trend was not observed for other insecticides tested. A positive correlation between temperature and percentage mortality caused by chlorpyriphos, imidacloprid, spinetoram, and thiamethoxam was found irrespective of infection status when evaluated at temperatures ranging between 20 and 37 °C. In contrast, a negative correlation between temperature and percentage mortality was observed for fenpropathrin for both infected and uninfected psyllids. Glutathione S-transferase levels were negatively correlated with temperature, whereas levels of cytochrome P450 and general esterase were not correlated with temperature fluctuations. These results indicate that altered insecticide susceptibility due to temperature may not be related to glutathione S-transferase, cytochrome P450, and general esterase levels. Diaphorina citri adults that carried the Las bacterium had reduced CYP4 transcript and protein levels, and ingested less than uninfected counterparts, as measured by the production of honeydew. Diaphorina citri adult feeding was greatest at 32 °C within the temperature range tested. Overall, annual temperature fluctuation does not appear to be a major factor impacting management of D. citri.

Life table studies of Earias vittella (Fabricius) on different hosts in the Insect Biotech Laboratory, Department of Entomology, Dr PDKV Akola, revealed that survival (lx) of immature stages of E. vittella on different hosts was 0.65 on okra, 0.56 on cotton, 0.54 on semi-synthetic diet and 0.51 on mesta. The net reproductive rate (Ro), at the end of each generation, of E. vittella was 81.91 on okra, 56.70 on cotton, 53.02 on semi-synthetic diet and 36.63 on mesta (Hibiscus cannabinus L.). The net reproductive rate (Ro) followed the same order as the survival rate (lx) on the different hosts. The innate capacity for increase in numbers (rm) ranged between 0.0888 and 0.1334 females/female/day. In descending order, the rm values on different hosts were okra (0.1334), cotton (0.1111), semi-synthetic diet (0.1029) and mesta (0.0888).Résumé. L'étude de la table de vie de E. vittella (Fabricius) élevé sur différentes plantes hô tes et sur milieu artificiel au laboratoire de Biotechnologie des insectes, du département d'entomologie (Dr PDKV Akola), a révélé que le taux de survie (lx) des stades immatures d' E. vittella sur les différents substrats est de 0,65 sur gombo, 0,56 sur coton, 054 sur milieu artificiel et 0,51 sur mesta (Hibiscus cannabinus L.). Le taux net de reproduction (Ro) d'E vittella par génération est de 81,91 sur gombo, 56,70 sur coton, 53,02 sur milieu artificiel et de 36,63 sur mesta. On observe une évolution comparable du taux net de reproduction (Ro) et du taux de survie sur les différents substrats. La capacité innée d'accroissement (rm) est comprise entre 0,0888 et 0,1334 femelles/femelle/jour. Les valeurs du rm sont par ordre décroissant 0,1334 (gombo), 0,1111 (coton), 0,1029 (milieu semi synthétique) et 0,0888 (mesta). Mots clés: table de vie, plante hô te, taux de survie, capacité innée d'accroissement, taux net de reproduction, Earias vittella, gombo, coton, Hibiscus cannabinus *

No abstract

The laboratory experiment was conducted during 2017-2018 to study the different biological attributes of Trichogramma chilonis Ishii as influenced by host eggs of different ages. Significantly maximum percent egg parasitization was noticed on eggs of Helicoverpa armigera (Hübner) with 62.39 percent which was at par with the Corcyra cephalonica (Stainton) eggs (60.36 percent). This was followed by Earias vittella Fabricius 46.31 percent. Less parasitized eggs were recorded in Leucinodes orbonalis Guenée (10.35 percent). Age of host eggs significantly affected the parasitization by T. chilonis. The maximum parasitization (58.87 percent) was noticed in fresh eggs i.e. 24 hrs old followed by 48 hrs (44.91 percent) while 72 hrs old eggs were less preferred by T. chilonis and could parasitize only 30.56 percent. Development period for parasitoid ranged between 8.66 to 9.44 days on different host eggs. The highest adult parasitoid longevity (7.22 days) was observed from the parasitized eggs of H. armigera which was at par with C. cephalonica (7.10 days), E. vittella (6.88 days) and L. orbonalis (6.88 days). However, the different lepidopteran eggs as well as age of host eggs did not show significant differences pertaining to percent adult parasitoid emergence. Fresh host eggs of 24 hrs could produce more female progeny of T. chilonis (54.30 percent) compared to 72 hrs old eggs (42.65 percent). The sex ratio (male: female) of emerging parasitoid progeny was observed highest on 24 hrs old eggs (1:1.55) followed by 48 hrs old eggs (1:1.23) while lowest sex ratio was observed on the eggs of 72 hrs old age (1:0.95). The maximum per day fecundity of T. chilonis was noticed on the 24 hrs old eggs (6.75) followed by 48 hrs old eggs (4.80). The lowest fecundity (2.05) of T. chilonis was observed on the 72 hrs old eggs, whereas the highest male-female ratio and fecundity was noticed on eggs of E.vittella among different hosts.