Changes in life history and morphological traits over 8 generations in the brown marmorated stink bug (Hemiptera: Pentatomidae) under mass-rearing conditions

Developing and establishing a permanent insect population under mass-rearing conditions is challenging, but it offers the opportunity to collect and compare life history, physiological, morphological, and behavioral traits in real-time and over multiple generations. Halyomorpha halys (St & aring;l, 1855) (Hemiptera: Pentatomidae), a serious agricultural insect pest in northern Italy, was used to establish a permanent mass-rearing protocol under controlled abiotic conditions. The study aimed to evaluate the impact of permanent laboratory rearing on various life history and morphological traits over 8 generations. Development time and developmental success rate of the eggs and nymphal stages, fecundity, mortality rate and body size of the adults were documented. In general, a significant variability was observed in both developmental success rate and developmental time for eggs and juvenile stages, although without an obvious trend. In adults, on the other hand, a common trend in fecundity, number of egg masses and survival was observed. All 3 parameters exhibited a marked decline beginning in the second generation, followed by a significant recovery starting from the seventh generation, indicating potential laboratory adaptation. The body size, on the other hand, showed a slight decrease from the second generation that remained almost constant in subsequent generations. While the results demonstrate the clear success of a continuous H. halys mass-rearing, they also show the current challenges and limits of rearing this invasive insect species under laboratory conditions over several generations without the addition of new individuals.