Effects of Temperatures on Immature Development and Survival of the Invasive Stink Bug (Hemiptera: Pentatomidae)

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a non-native stink bug that feeds primarily on cole crops and wild mustards. Its invasion into desert agriculture in California and Arizona presents a conundrum between rapid pest development at warm temperatures and severe damage to cool season crops. In this study, the development and survival of B. hilaris were determined at nine constant temperatures (ranging from 20-42 degrees C) when reared on organically grown broccoli florets. Egg hatching was greatly delayed at 20 degrees C, and first instar nymphs did not survive at this temperature. No eggs hatched at 42 degrees C. The highest survival rates (70.0-86.7%) of B. hilaris were observed at temperatures ranging from 24 to 35 degrees C. The total developmental rate of B. hilaris from egg to adult increased from 0.027 to 0.066/d from 24 to 35 degrees C, and then slightly dropped to 0.064/d at 39 degrees C. Based on the linear model, B. hilaris requires 285.4 degree-days to complete its development. The Briere 1 model predicted the lower and upper temperature thresholds as 16.7 and 42.7 degrees C, respectively. The optimal temperature for development (T-Opt) was estimated as 36 degrees C. According to the results, B. hilaris is well adapted to warm conditions, and temperatures of 33-39 degrees C are well suited for B. hilaris development. Information from this study helps explain the rapid range expansion of B. hilaris across the southern United States and will be instrumental in predicting future expansion across the rest of the country and in other parts of the world. The relationship between thermal thresholds and invasion dynamics of this pest are discussed.