CLIMEX simulated predictions of Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) geographical distribution under climate change situations in India

An attempt was made to understand the influence of 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 AlB 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 time-frames 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.