Browsing by Author "Madhu T. N."

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    Effect of temperature on the biological parameters of pink bollworm, Pectinophora gossypiella Saunders (Lepidoptera: Gelechiidae)
    (2024) Madhu T. N.; Mohan, K.M; Keerthi, M.C; Prabhulinga, T; Thube, S. H.; Shah, V; Elansary, H.O.; Mousa, I.M.; Mohamed A. El-Sheikh
    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
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    Field detection, molecular characterization and biology of the tea tortrix, Homona coffearia Neitner (Lepidoptera: Tortricidae) on Cocoa (Theobroma cacao. L) from India
    (2024) Madhu T. N.; Saneera E. K; R. Thava Prakasa Pandian; Bhavishya; Nagaraja N. R; M. Chaithra; S. Elain Apshara; B. J. Nirmal Kumar; Diwakar Y; Suchithra M; Rajesh M. K; Vinayaka Hegde
    Cocoa (Theobroma cacao. L) is an important commercial crop widely cultivated in humid tropical regions; however, its production faces various constraints including insect pests. The survey conducted in 2022–2023 found significant damage to cocoa nurseries and fields caused by the larvae of H. coffearia. The caterpillars web the young leaves, feeds within the sheltered nests and affects the crop canopy. The percent incidence was 27.55 ± 1.81% in the nursery and 43.77 ± 3.42% in open fields. A detailed morphological examination and molecular characterization using the mitochondrial cytochrome c oxidase I (COI) gene confirmed the identity of the pest as H. coffearia. The study also documented the key biological parameters of H. coffearia on cocoa under laboratory conditions. The life cycle from egg to adult was completed in about 49 ± 2.32 days. Female moths laid an average of 106 ± 3.48 eggs, which hatched into larvae that underwent five instars before pupation. Both the larval and pupal stages lasted around 27.69 ± 0.72 and 7.72 ± 0.17 days respectively. To our knowledge, this is the first report of the tea tortrix, H. coffearia infesting cocoa in India. As a polyphagous pest, the ability of H. coffearia to adapt and feed on new host plants like cocoa poses a significant threat to cocoa production. The findings of this work highlight the need for further research on the population dynamics, damage potential and management strategies for this emerging pest in cocoa ecosystems.