The small tomato borer, Neoleucinodes elegantalis (Guenée, 1854) is a multivoltine pest of tomato and other cultivated solanaceous plants. The knowledge on how N. elegantalis respond to temperature may help in the development of pest management strategies, and in the understanding of the effects of climate change on its voltinism. In this context, this study aimed to select models to describe the temperature-dependent development rate of N. elegantalis and apply the best models to evaluate the impacts of climate change on pest voltinism. Voltinism was estimated with the best fit non-linear model and the degree-day approach using future climate change scenarios representing intermediary and high greenhouse gas emission rates. Two out of the six models assessed showed a good fit to the observed data and accurately estimated the thermal thresholds of N. elegantalis. The degree-day and the non-linear model estimated more generations in the warmer regions and fewer generations in the colder areas, but differences of up to 41% between models were recorded mainly in the warmer regions. In general, both models predicted an increase in the voltinism of N. elegantalis in most of the study area, and this increase was more pronounced in the scenarios with high emission of greenhouse gases. The mathematical model (74.8%) and the location (9.8%) were the factors that mostly contributed to the observed variation in pest voltinism. Our findings highlight the impact of climate change on the voltinism of N. elegantalis and indicate that an increase in its population growth is expected in most regions of the study area.

Experiments were conducted to establish low temperature thresholds for initiation of bud sprouting in dormant vegetative propagules of johnsongrass, purple nutsedge, and yellow nutsedge, and seed germination in cotton. Weed propagule sprouting and cotton seed germination responses to temperature were determined in a series of experiments conducted on a temperature gradient bar. Four calculated indices were used to quantify germination: mean percent germination per day, reciprocal median response time, and two versions of germination rate index. Data were analyzed as a series of regressions of germination indices against temperature. Maximum and minimum temperatures for germination were derived directly from the regressions and compared among species. Yellow nutsedge had the lowest temperature threshold (6 C), while the other species had low temperature thresholds of 11 to 12 C. Upper temperature thresholds were similar among species and ranged from 42 to 44 C. The lower low temperature threshold of yellow nutsedge sprouting compared to those for cotton, johnsongrass, and purple nutsedge suggests that early establishment by yellow nutsedge is an important factor in competitiveness in mixtures of these species. The results presented here suggest that application of principles derived from studies in seed biology might advance our understanding and ability to manage perennial weeds.