Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) is an important type of thrip and a polyphagous pest, which poses a serious threat to many crops, especially those in tropical regions of China. Its feeding behavior and the damage caused vary among different host plant species and are affected by ambient temperature and plant nutrients as well. The digestion rate is an important index for directly observing the digestion process, but there have been no studies directly measuring the digestion in thrips under the influence of different temperatures and host plants. Here, the digestion rate of F. intonsa was assessed by using a molecular diagnostic tool. We also determined the nutrient content in three host plant (mango, cowpea, and pepper), including soluble proteins, free fatty acids, soluble sugars, and water. The results showed that the high and low temperatures (16 °C and 32 °C) both seemed to accelerate the digestion of F. intonsa compared to the optimal temperature (26 °C) and the protein content of plants played an important role in the digestive response of F. intonsa to temperature changes. The findings can help reveal the feeding damage caused by F. intonsa to different plants and help to better understand its feeding ecology, according to its interaction with the host plant.

Predators can induce phenotypic plasticity in prey through selection driven by predation risk. However, defense plasticity is rarely reported in insects, let alone trans-generational plasticity, meaning the mechanisms underlying plasticity, how it impacts ecosystem evolution and how it might be exploited in pest control are poorly understood. Here we examine the morphological plasticity of small brown planthoppers (SBPHs), Laodelphax striatellus, elicited by caged predators, Paederus fuscipes in the parent or F1 generation and reveal the risk cues mediating these effects. We also uncover the survival outcomes in SBPHs with predator-induced defensive morphological traits by examining their survival probability and behavioral plasticity. Results showed that caged predators or predator odor cue gave rise to a higher proportion of long-winged, female SBPHs in the parent and F1 generations, but the proportion of males and their wing length were unaffected. The visual cue from predators elicited weaker effects. Surprisingly, we discovered these long-winged forms suffered a lower predation rate when attacked by P. fuscipes, owing to an enhanced agility level. Our results suggest the within- and trans-generational plasticity of induced defenses may cause profound effects on SBPH population dynamics and prey-predator interaction. Understanding this interaction and its underlying mechanisms illuminates important aspects of ecosystem evolution and helps predict pest dispersal or migration, which in turn may be exploited for pest control.

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.