K. K. Sharma

Attractancy potential of culturable bacteria from the gut of peach fruit fly, Bactrocera zonata (Saunders)

Bacteria were isolated from the midgut of laboratory and field adult flies of Bactrocera zonata (Saunders) (Diptera: Tephritidae), a widely distributed fruit crop pest in India. Nine bacteria were isolated and identified as members of genera Bacillus, Enterobacter, Klebsiella and Stenotrophomonas based on culture-dependent and 16S rRNA gene sequence analysis. The results showed that bacterial diversity in the gut of B. zonata adults differed between the laboratory and field flies but Stentrophomonas maltophilia, Enterobacter cloacae and Klebsiella pneumoniae were present in both populations. A significant difference was found in the attractancy between the different age groups when flies were fed with protein or were protein-starved. Among bacteria, E. cloacae and K. pneumoniae had the highest attraction to flies over other bacteria across all age groups of flies. This study provides the first description of the gut microbial community of B. zonata and their role as attractants.

Characterization of culturable gut bacterial isolates from wild population of melon fruit fly (Bactrocera cucurbitae) and assessing their attractancy potential for sustainable pest management

The melon fruit fly, Bactrocera cucurbitae (Coquillett) poses a serious threat to cucurbit production worldwide. Its management by conventional means remains difficult due to their proclivity to oviposite in fruit. In view of the increasing environmental safety concerns, use of biocontrol agents for sustainable pest control holds immense potential. Given this, the study intended to identify the cultivable bacteria inhabiting the intestinal tract of adult male and female melon fruit flies (Bactrocera cucurbitae) separately from field-collected population, and to assess the attractiveness of these bacteria to the fly. All selected bacterial isolates were identified and characterized based on morphological, biochemical and 16S rRNA gene sequence. Bacterial community identified in the gut of B. cucurbitae predominantly composed of Enterobacteriaceae followed by Staphylococcaceae, Enterococcaceae, Bacillaceae and Brucellaceae. Further, the laboratory bioassay was employed to examine the attractiveness of the supernatant as well as whole culture broth of 10 different species of bacteria to B. cucurbitae adults. Among these, Klebsiella oxytoca and Citrobacter freundii followed by Bacillus cereus were found highly attractive to fruit flies. The field experiment using supernatant of two bacteria demonstrated that the K. oxytoca was significantly more attractive to female flies followed by C. freundii.

Persistence of thiacloprid and deltamethrin residues in tea grown at different locations of North-East India

In order to examine the residues of thiacloprid (90 and 180 g a.i./ha) and deltamethrin (10 and 20 g a.i./ha) in fresh tea leaves, made tea and tea infusion, field experiments were conducted at three different locations viz. Kamalpur tea estate, Darjeeling; West Bengal, Teok tea Estate and AAU, Jorhat; Assam in India. Regardless of location and doses, residues of both the insecticides dissipated following first order kinetics. The half-life of Thiacloprid (4.93-5.38 days) was longer than that of deltamethrin (1.78-1.94 days). Processing of green tea leaves reduced the residue level of thiacloprid and deltamethrin in made tea. No residues of both these insecticides could be detected in tea infusion. With respect to the phenolic distribution in tea, a marked increase in total catechin monomers with thiacloprid and greater accumulation of EGCG and ECG (indices of phenol quality) with deltamethrin were observed.

Persistence, dissipation and consumer risk assessment of a combination formulation of flubendiamide and deltamethrin on Cucumber

ABSTRACT Multi-location supervised field trials were conducted in India at four locations of the All India Network Project (AINP) on Pesticide Residues to study the persistence, dissipation and risk assessment of flubendiamide and deltamethrin on cucumber (Cucumis sativus). Residues of flubendiamide and deltamethrin on cucumber resulting from three spray applications of a combination formulation (flubendiamide 90% + deltamethrin 60%, 150 SC) at recommended (22.5 + 15 g a.i./ha) and double the recommended (45 + 30 g a.i./ha) dose were analysed. On the basis of persistence and dissipation studies, the half- life (T1/2) of flubendiamide on cucumber varied from 1.40 to 2.98 (recommended dose) and 1.55 to 2.76 days (double the recommended dose), while that of deltamethrin ranged from 2.5 to 4.9 (recommended dose) and 2.7 to 3.9 days (double the recommended dose) at the four locations. On the basis of supervised field trial data and using OECD calculator, MRLs in the combination product of 3 mg kg−1 for flubendiamide and 1.5 mg kg−1 for deltamethrin has been proposed for consideration by the Food Safety and Standards Authority of India (FSSAI). Codex, EU and EPA have fixed MRL of 0.2 mg kg−1 for flubendiamide and deltamethrin.