Thermal Requirements and Degree-Day Accumulation Model for Adult Emergence of Eurygaster maura (Hemiptera: Scutelleridae)

Abstract

The sunn pest Eurygaster maura is a significant cereal pest, with adult emergence timing playing a critical role in outbreak prediction and management in wheat-based agroecosystems. Thermal requirements and degree-day (DD) accumulation models were developed to estimate adult emergence under variable environmental conditions. Field populations were monitored across multiple cereal-growing regions, and developmental stages were recorded in relation to daily temperature fluctuations. Laboratory rearing experiments were conducted under controlled temperatures to determine lower developmental thresholds and thermal constants for immature stages. Results indicated a clear temperature-dependent development pattern, with accelerated growth and reduced developmental time observed at higher temperatures within the optimal biological range. The lower developmental threshold for pre-adult stages was estimated using linear regression analysis, and the thermal constant required for adult emergence was calculated based on accumulated degree-days. Field validation demonstrated strong agreement between predicted and observed adult emergence timings, confirming the reliability of the model under natural conditions. Degree-day accumulation curves effectively captured seasonal emergence patterns, with peak adult emergence coinciding with late spring to early summer temperature regimes. Variability in emergence timing among regions was associated with local climatic differences, particularly in minimum temperature fluctuations and heat unit accumulation rates. The model provides a useful predictive tool for forecasting pest emergence and optimizing the timing of integrated pest management interventions. Early warning based on thermal accumulation can improve decision-making for insecticide application and reduce crop damage.