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The brown planthopper, Nilaparvata lugens Stal is a key pest of rice in Asia, causing extensive crop losses and transmitting major viruses. We analysed mitochondrial cytochrome oxidase I ( mt COI) sequences from 63 field-collected samples representing 21 populations across ten states to understand its genetic structure across India’s diverse agroclimatic zones. Our analysis revealed two highly conserved haplotypes, with one major haplotype shared across over 85% of individuals. This consistent haplotype distribution is supported by a TCS network and minimal mutational steps and this reflects strong genetic cohesion across geographically distant populations. Population genetic parameters, neutrality tests, and mismatch distribution patterns support a recent demographic expansion of N. lugens in India. A majority of genetic variation was observed within populations, with only subtle regional differences, as confirmed by AMOVA and phylogenetic tree topology. These results indicate robust gene flow and suggest that Indian populations are highly interconnected, likely facilitated by seasonal migration and shared agricultural practices. Our study offers one of the most comprehensive mitochondrial diversity assessment of Indian N. lugens to date and provides critical genetic benchmarks for future monitoring, resistance management, and predictive modelling of BPH outbreaks in the subcontinent.

Rhizospheric bacteria are soil bacteria inhabiting the near-root zone, with multifarious activities including the promotion of plant growth, nutrient mobilization, and biological control of pests and diseases. Rhizobacteria produce microbial volatile organic compounds (mVOCs) that can be utilized as biocontrol components against phytopathogenic fungi. Here, we analyzed the mVOCs produced from cotton rhizobacteria and their role in biological control of the fungus Macrophomina phaseolina . Twelve endospore-forming rhizobacterial strains were isolated from the cotton rhizosphere and screened for their biocontrol potential. Three rhizobacterial strains , Bacillus cereus CICR-D3, Bacillus aryabhattai CICR-D5 and Bacillus tequilensis CICR-H3 were evaluated for mVOCs using gas chromatography-mass spectrometry (GC-MS). Major antifungal mVOCs i.e. Benzene, 1, 3-diethyl- and Benzene, 1, 4-diethyl followed by naphthalene, m-ethylacetophenone and ethanone, 1-(4-ethylphenyl) were produced by these strains. The relative abundance of mVOCs released was highest from CICR-D3 followed by CICR-D5 and CICR-H3. Bi-compartmental Petri plate assay against M. phaseolina showed that the CICR-D3 strain was the most effective in inhibiting the mycelial growth (86.70 ± 0.50%), followed by the CICR-D5 (69.27 ± 0.17%) and CICR-H3 (62.84 ± 0.50%) strains. Furthermore, in vivo co-inoculation in a polyhouse revealed that severity of root rot caused by M. phaseolina was reduced by 72.74% in potted cotton plants inoculated with CICR-D3 strain, followed by strains CICR-D5 (69.04%) and CICR-H3 (66.60%). To the best of our knowledge, the specific volatiles are being reported for the first time from native cotton rhizobacterial strains, which provides new insight into cotton rhizobacteria and their antifungal mVOCs as an eco-compatible strategy for cotton root rot management.

Background Following the introduction of Bacillus thuringiensis ( Bt ) cotton in India, its cultivation expanded rapidly from 29 000 hectares in 2002–2003 to 3 353 000 hectares in 2006–2007 with Bollgard I. To delay and manage resistance to the Cry1Ac toxin, genotypes expressing two toxins, Cry1Ac and Cry2Ab (Bollgard II), were introduced in 2006. By 2010, these Bollgard II genotypes had gradually replaced Bollgard I to enhance resistance management. However, the widespread use of Bt cotton increased selection pressure, leading to field resistance in the pink bollworm (PBW), Pectinophora gossypiella . Conventional bioassays used to confirm resistance are time-consuming. To address this limitation, bulk segregant analysis (BSA) has been employed to identify simple sequence repeat (SSR) markers for Cry resistance, providing a quicker and more cost-effective assessment method. Results Among the 59 Pectinophora gossypiella populations analyzed across India during 2022–2023, the Nagpur population exhibited the highest resistance levels, with median lethal concentration (LC 50 ) values of 7.682 µg·mL −1 for Cry1Ac (resistance ratio = 960) and 12.574 µg·mL −1 for Cry2Ab (resistance ratio = 2 096). Furthermore, the Nagpur PBW strain was used in bulk segregant analysis and identified three polymorphic SSR markers (notr15F/r15allR2, 164Pgcad5F/163Pgcad3R and gF47/gR47) linked to Cry1Ac resistance. The marker pair gF47/gR47 also showed polymorphism in Cry2Ab-resistant individuals. These markers were further validated during the 2023–2024 season using samples collected from 15 locations across India, including larvae, pupae, and adult males. The molecular marker results were consistent with traditional larval bioassay outcomes, confirming their association with resistance phenotypes. Conclusion Using specific SSR markers, a rapid and highly reliable technique for identifying resistance in Indian populations of pink bollworms to Cry toxins (Cry1Ac and Cry2Ab) has been found. The whole process was dependable, quick, robust, and cost-effective.

Oviposition deterrents are the info-chemicals that modifies the behavior of conspecific female insects either to settle on the treated surface or to lay eggs thereafter, reducing intra-specific competition. Drawing from our prior research, it has been established that the fatty acids (Oleic and linoleic acid) found in vegetable oils exhibit properties of oviposition deterrence. The present study was designed to investigate the oviposition deterrent activity of vegetable oils against pink bollworm. Six different vegetable oils, namely groundnut, sunflower, soybean, rice bran, safflower and sesame containing oleic and linoleic acid as major fatty acids were selected and evaluated under laboratory and field conditions. Under laboratory conditions, oils were tested at concentrations ranging from 0.5 to 3.0%, with methanol as control. Cotton twigs with squares served as the oviposition substrate and the total number of eggs laid by the moth was counted and compared to control. The results demonstrated a significant reduction in number of eggs laid as evident from the avoidance index (AI) and percent effective deterrence (PED) values of vegetable oil treatments. Descending order of oviposition deterrent efficacy as revealed from AI and PED values, groundnut (AI = 0.74, PED = 84.40%) > soybean (0.67, 79.87%) > sesame (0.65, 78.59%) > sunflower (0.59, 74.09%) > rice bran (0.57, 71.93%) > safflower (0.55, 71.09%). Our findings were further validated through field studies conducted during 2019–2020 and 2020–2021, confirming effectiveness of the selected vegetable oils in reducing the boll damage. Study demonstrates the promising oviposition deterrent effect of vegetable oils against Pectinophora gossypiella and hold great potential as an eco-friendly component in integrated pest management program of cotton.

Aim: This preliminary study aimed to investigate the movement patterns of Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) larvae in the rosette flowers. Methodology: Field experiments conducted on the migration behavior of pink bollworm larvae with respect to rosette flowers in cotton fields. Observations included monitoring infested flowers, larval stage duration within rosette flowers, and larval movement to soil for pupation, larval mortality post-drop, and larval migration to early bolls, all conducted without insecticide application to reflect natural conditions. Results: The movement of the larvae was tracked and recorded from the start of flowering to the boll formation stage. Nearly, 44.88% of the larvae present on the infested flowers had moved to the soil for pupation, while 14.29% had moved to newly formed bolls on the same rosette flower. Additionally, 30.90% of the larvae had moved to dry leaf debris on the soil, and the remaining 9.93% either escaped or died due to environmental factors such as damp soil. Notably, the study showed that dry soils or light debris accumulation were the most favorable environments for pink bollworm larvae. Interpretation: The present study has generated useful information regarding the movement of PBWs larvae from rosette flowers to bolls that contribute to infestation. Hence, by implementing integrated pest management strategies during the early crop periods between 60 and 100 DAS, green boll infestations can be avoided and economic yields improved. Key words: Larval movement, Pest carryover, Pest management, Rosette flower

Aim: To identify natural incidence pattern of pink bollworm larval parasitoids across different cotton growing zones in India. Methodology: Green bolls of cotton were collected from farmers field across India encompassing Northern, Central and Southern regions of cotton cultivation. In total 59 locations were selected for sampling and from each cotton field, five hundred matured green bolls were collected, packed and transferred to laboratory at CICR, Nagpur. Dead/inactive larvae were placed individually in plastic tubes under controlled laboratory conditions to monitor párásítóid emergence. Percent parasitization and párásítóid emergence were calculated accordingly. Results: The pink bollworm larval recovery varied among locations, with the highest average recovery and parasitised larvae observed in the Northern zone (480.50 and 12.10 larvae). Additionally, the average parasitization rate was higher in the Northern cotton zone (2.46 %) compared to the Southern (2.16 %) and Central zones (1.70 %). In terms of parasitoids, the Southern zone exhibited the highest average number of Bracon lefroyi (9.17 ± 3.59) with a range of 3.0-17.0 parasitoids, while the Northern zone recorded the highest average number of Apanteles angaleti (9.70 ± 2.83) with a range of 6.0-15.0 parasitoids. Interpretation: The natural parasitization of pink bollworm larvae by Bracon lefroyi and Apanteles angaleti ranged from 0.43 to 4.33 per cent across various cotton-growing zones. This natural occurrence presents a hopeful strategy for controlling pink bollworm populations, potentially reducing the need for chemical interventions and minimizing crop damage.

Aim: To identify natural incidence pattern of pink bollworm larval parasitoids across different cotton growing zones in India. Methodology: Green bolls of cotton were collected from farmers field across India encompassing Northern, Central and Southern regions of cotton cultivation. In total 59 locations were selected for sampling and from each cotton field, five hundred matured green bolls were collected, packed and transferred to laboratory at CICR, Nagpur. Dead/inactive larvae were placed individually in plastic tubes under controlled laboratory conditions to monitor parasitoid emergence. Percent parasitization and parasitoid emergence were calculated accordingly. Results: The pink bollworm larval recovery varied among locations, with the highest average recovery and parasitised larvae observed in the Northern zone (480.50 and 12.10 larvae). Additionally, the average parasitization rate was higher in the Northern cotton zone (2.46 %) compared to the Southern (2.16 %) and Central zones (1.70 %). In terms of parasitoids, the Southern zone exhibited the highest average number of Bracon lefroyi (9.17 ± 3.59) with a range of 3.0-17.0 parasitoids, while the Northern zone recorded the highest average number of Apanteles angaleti (9.70 ± 2.83) with a range of 6.0-15.0 parasitoids. Interpretation: The natural parasitization of pink bollworm larvae by Bracon lefroyi and Apanteles angaleti ranged from 0.43 to 4.33 per cent across various cotton-growing zones. This natural occurrence presents a hopeful strategy for controlling pink bollworm populations, potentially reducing the need for chemical interventions and minimizing crop damage. Key words: Apanteles angaleti, Bracon lefroyi, Cotton, Larval parasitoid, Pink bollworm

Pink bollworm, Pectinophora gossypiella (Saunders) infestation on Bt cotton is a major concern to cotton production in India. The genetic diversity and phylogeographic structure of the insect in light of PBW resistance needs to be revisited. The objective of this study was to identify different haplotypes of pink bollworm and their distribution in India. To achieve this we studied the population structure in 44 cotton growing districts of India. The partial mitochondrial COI sequence analyses of 214 pink bollworm populations collected from 44 geographical locations representing 9 cotton growing states of India were analysed. Genetic diversity analysis exhibited presence of 27 haplotypes, among them Pg_H1 and Pg_H2 were the most common and were present in 143 and 32 populations, respectively. Distributions of pairwise differences obtained with partial COI gene data from the overall Indian populations are unimodal, suggesting population expansion in India. Significant neutrality test on the basis of Tajima’ D and Fu’s Fs presented a star-shaped haplotype network together with multiple haplotypes. The unimodal mismatch distribution, rejection of neutrality test with significant negative values supported the theory of demographic expansion in cotton pink bollworm populations in India. Genetic data not only provides us with a perspective of population genetics, but also that the two populations of pink bollworm, those occurring early in the season are genetically close to the late season populations with respect to their partial CO1 region. Resistance to Cry toxins does not seem to have had an impact on this region of the mt DNA in populations of pink bollworm.

Pink bollworm (PBW) Pectinophora gossypiella is an important pest cotton worldwide. There are multiple factors which determines the occurrence and distribution of P. gossypiella across different cotton growing regions of the world, and one such key factor is ‘temperature’. The aim was to analyze the life history traits of PBW across varying temperature conditions. We systematically explored the biological and demographic parameters of P. gossypiella at five distinct temperatures; 20, 25, 30, 35 and 40 ± 1 °C maintaining a photoperiod of LD 16:8 h. The results revealed that the total developmental period of PBW shortens with rising temperatures, and the highest larval survival rates were observed between 30 °C and 35 °C, reaching 86.66% and 80.67%, respectively. Moreover, significant impacts were observed as the pupal weight, percent mating success, and fecundity exhibited higher values at 30 °C and 35 °C. Conversely, percent egg hatching, larval survival, and adult emergence were notably lower at 20 °C and 40 °C, respectively. Adult longevity decreased with rising temperatures, with females outliving males across all treatments. Notably, thermal stress had a persistent effect on the F1 generation, significantly affecting immature stages (egg and larvae), while its impact on reproductive potential was minimal. These findings offer valuable insights for predicting the population dynamics of P. gossypiella at the field level and developing climate-resilient management strategies in cotton.