Current Science

V. Sridhar ¹, A. Verghese ², L. S. Vinesh ¹, M. Jayashankar ¹, P. D. Kamala Jayanthi ¹

Affiliations
1 Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bengaluru 560 089, IN
2 National Bureau of Agriculturally Important Insects, Bellary Road, Bengaluru 560 024, IN

Abstract

climate change on future potential distribution of Oriental fruit fly (OFF), Bactrocera dorsalis (Hendel), a polyphagous pest on a wide variety of fruit crops in India. Prediction of the potential distribution of OFF was done for different time-frames (2030, 2050, 2070 and 2090) under the A1B climate change scenario (CSIRO-Mk3.0, a global climate model) using CLIMEX software. The model predicted an overall gradual decrease in terms of area suitability for OFF in India by 2090 due to increase in various stress factors to the pest. In temperate regions of the north and northeastern parts, incidence of the pest may increase due to rise in temperature coupled with decrease in cold stress. In North India, the model predicts the regions of Jammu&Kashmir, Himachal Pradesh, Uttarakhand, Haryana and Punjab to be more climatically suitable for OFF by 2030 and there is an expected steady increase in suitability by 2050, 2070 and 2090. The CSIRO model for North East indicated that by 2090, Assam, Arunachal Pradesh and Manipur would become highly suitable for the pest. The projected range expansion in terms of area suitability was recorded up to 100 km in temperate regions. Central and western India are projected to become progressively less suitable by 2030, 2050 and totally unsuitable by 2090. In South India, there was a slight reduction in climatic suitability for OFF in terms of ecoclimatic index over timeframes 2030, 2050, 2070, 2090 as highly suitable, optimal, suitable and marginally suitable respectively. Regression analysis was carried out using growth index obtained from CLIMEX and pest trap counts. Additionally, field level validation of the model was carried out for selected locations.

Keywords

Bactrocera Dorsalis, Climate Change, Geographical Distribution, Oriental Fruit Fly.

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N. Bakthavatsalam ¹, J. Vinutha ¹, P. Ramakrishna ¹, A. Raghavendra ¹, K. V. Ravindra ¹, A. Verghese ¹

Affiliations
1 ICAR-National Bureau of Agricultural Insect Resources, P. B. No. 2491, H. A. Farm Post, Bengaluru 560 024, IN

Abstract

Autodetection is an olfactory behavioural process where the females of some species respond to their own pheromonal blends. Through electroantennogram studies it has been proved that the gravid females of Helicoverpa armigera (Hubner) respond to their pheromone blend consisting of Z-11-hexadecenal and Z-9- hexadecenal in the ratio 97 : 3. Male antennae respond more strongly than virgin female antennae. However, antennae of gravid females elicit strong response than unmated males. Also, males showed strong responses in cross-wind flying in wind tunnel experiments, when sex pheromone blends were used. Virgin females and gravid females showed poor response in wind-tunnel studies. The ovipositional experiment where gravid females were allowed to oviposit in the presence and absence of pheromone odours indicated that there was no difference in the number of eggs laid. Through morphological studies, it has been proved that the females also possess sensilla trichoidea, destined to perceive the pheromone blends, though lesser in number than the males. These results support the hypothesis that autodetection of sex pheromones exists in females of H. armigera and is thought to function as a mechanism to induce dispersal under high population densities.

Keywords

Autodetection, Electroantennogram, Helicoverpa armigera, Oviposition, Synthetic Sex Pheromone.

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