Insects have developed dormancy mechanisms to survive coldness in winters. The specific forms of winter dormancy, however, vary among different geographical and climatic zones and species. While there is extensive research on winter dormancy in insect pests and parasitoids in temperate zones, our understanding of how predatory insects, such as predatory stink bugs in subtropical regions, cope with cold winters and the specific forms of dormancy they undergo remains limited. The effects of winter temperatures on the population dynamics, development, and reproduction of the predatory stink bug Eocanthecona furcellata in the subtropics were investigated through greenhouse and laboratory experiments. E. furcellata exhibits two distinct peaks in population distribution throughout the year: one in April–May and another in October–November. Interestingly, the proportions of adults show an opposite pattern to the population dynamics, with the highest proportions of adults observed during the winter and summer seasons, when temperatures are the lowest and the highest, respectively. Laboratory studies showed that E. furcellata reared at lower temperatures (16 °C, 18 °C, and 20 °C) experienced prolonged development and higher mortality rates for eggs and nymphs compared to higher temperatures (22 °C and 26 °C). Further experiments observed that E. furcellata adults reared at 16 °C, 18 °C, and 20 °C entered into winter dormancy, where ovarian development was either completely halted or slowed down. The observed high proportion of E. furcellata adults and low proportion of nymphs during the cold winter months align well with the dormancy period. This study sheds light on the underlying mechanisms driving the population dynamics of E. furcellata during the subtropical winter. These findings have significant implications in accurately predicting the population dynamics of E. furcellata, implementing effective field release strategies, and optimizing cold storage techniques in the context of biological control programs.

Eocanthecona furcellata is an important predatory stinkbug that attacks many lepidopteran pests. For mass-rearing, artificial diets are used to rear this predator in the laboratory; however, the fitness of the predators is reduced, and little is known about the cause. Since gut microbiota plays vital roles in the digestion and development of many hosts and can consequently affect host fitness, an understanding of the microbial community composition of E. furcellata may help to solve this unresolved problem. We compared the development and reproduction of E. furcellata reared on an artificial diet, and a natural (Spodoptera litura) or semi-natural (Tenebrio molitor) diet, and then the midgut microbiota were assessed using high-throughput 16S rRNA. The results of the high-throughput 16S rRNA show that the bacterial richness and diversity in the artificial diet gut samples increased considerably compared with the other samples. Proteobacteria and Firmicutes were the dominant phyla in E. furcellata. At the genus level, Serratia (however, the relative abundance was lower in the artificial diet gut samples), Enterococcus, and an uncultured bacterium genus of family Enterobacteriaceae, were dominant. The midgut microbiota components significantly differed among the diets, indicating that the gut bacteria had a dietary association with E. furcellata. This study provides a better understanding of midgut microbiota and the artificial diets that might affect them in E. furcellata.