The present study features the estimation of number of generations of tobacco caterpillar, Spodoptera litura. Fab. on peanut crop at six locations in India using MarkSim, which provides General Circulation Model (GCM) of future data on daily maximum (T.max), minimum (T.min) air temperatures from six models viz., BCCR-BCM2.0, CNRM-CM3, CSIRO-Mk3.5, ECHams5, INCM-CM3.0 and MIROC3.2 along with an ensemble of the six from three emission scenarios (A2, A1B and B1). This data was used to predict the future pest scenarios following the growing degree days approach in four different climate periods viz., Baseline-1975, Near future (NF) -2020, Distant future (DF)-2050 and Very Distant future (VDF)—2080. It is predicted that more generations would occur during the three future climate periods with significant variation among scenarios and models. Among the seven models, 1–2 additional generations were predicted during DF and VDF due to higher future temperatures in CNRM-CM3, ECHams5 & CSIRO-Mk3.5 models. The temperature projections of these models indicated that the generation time would decrease by 18–22% over baseline. Analysis of variance (ANOVA) was used to partition the variation in the predicted number of generations and generation time of S. litura on peanut during crop season. Geographical location explained 34% of the total variation in number of generations, followed by time period (26%), model (1.74%) and scenario (0.74%). The remaining 14% of the variation was explained by interactions. Increased number of generations and reduction of generation time across the six peanut growing locations of India suggest that the incidence of S. litura may increase due to projected increase in temperatures in future climate change periods.

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Predicted increase in temperature and atmospheric CO 2 concentration will influence the growth of crop plants and phytophagous insects. The present study, conducted at the Central Research Institute for Dryland Agriculture, Hyderabad, India, aimed at 1) construction of life tables at six constant temperatures viz ., 20, 25, 27, 30, 33, and 35 ± 0.5°C for Spodoptera litura (Fabricius) (Noctuidae: Lepidoptera) reared on sunflower ( Helianthus annus L.) grown under ambient and elevated CO 2 ( e CO 2 ) (550 ppm) concentration in open top chambers and 2) prediction of the pest status in near future (NF) and distant future (DF) climate change scenarios at major sunflower growing locations of India. Significantly lower leaf nitrogen, higher carbon and higher relative proportion of carbon to nitrogen (C:N) were observed in sunflower foliage grown under e CO 2 over ambient. Feeding trials conducted on sunflower foliage obtained from two CO 2 conditions showed that the developmental time of S. litura (Egg to adult) declined with increase in temperature and was more evident at e CO 2 . Finite (λ) and intrinsic rates of increase ( rm ), net reproductive rate ( Ro ), mean generation time, (T) and doubling time (DT) of S. litura increased significantly with temperature up to 27–30°C and declined with further increase in temperature. Reduction of ‘ T ’ was observed from maximum value of 58 d at 20°C to minimum of 24.9 d at 35°C. The DT of population was higher (5.88 d) at 20°C and lower (3.05 d) at 30°C temperature of e CO 2 . The data on these life table parameters were plotted against temperature and two nonlinear models were developed separately for each of the CO 2 conditions for predicting the pest scenarios. The NF and DF scenarios temperature data of four sunflower growing locations in India is based on PRECIS A1B emission scenario. It was predicted that increased ‘ rm ’, ‘λ’, and ‘ Ro ’ and reduced ‘ T ’ would occur during NF and DF scenario over present period at all locations. The present results indicate that temperature and CO 2 are vital in influencing the population growth of S. litura and pest incidence may possibly be higher in the future.

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