Invasion risk of the South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in India: predictions based on MaxEnt ecological niche modelling

The South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a recent invasion in India, causing widespread infestations in tomato crop in the States of central peninsula, especially Maharashtra and Karnataka. Hitherto, this pest was not reported to occur in India and thus presumed to be of exotic origin. The present study attempted to delineate the potential habitat suitability of geographical areas for spread and distribution of T. Absoluta in India. We have modelled the potential habitat distribution of T. absoluta using algorithm in Maxent, a maximum entropy modelling program. The climate niche for T. absoluta was developed based on the relationship between presence only data for 64 places and a reference climate data for the year 2000. This established relationship was then used to predict the changes in potential distribution under future climatic conditions of 2050. The future climate data from SRES A1b emission scenario at a resolution of 10 arc minutes were used for analysing climate change impacts. The predictions from Maxent were mapped in DIVA GIS, an open source computer aided tool for mapping and analysing spatial data. The established model in Maxent gave a reasonable estimate of T. absoluta range with better discrimination of suitable and unsuitable areas for its occurrence under current and future climatic conditions. This was evident from the highest value of AUC i.e. 0.968 and 0.874 for training and test data, respectively. A Jacknife test for variable importance indicated that Bio3 (isothermality) with highest gain value was the most important abiotic factor influencing the potential habitat distribution of T. absoluta. Temperatures >30 degrees C and precipitation >500 mm were found to have detrimental effects on distribution of T. absoluta. The modelled habitat distribution of T. absoluta will be a useful guide for researchers and plant protection workers to frame appropriate management strategies against this invading pest insect to cope with the future climate change conditions.