The reception of chemical cues in the environment is essential for the survival of almost all organisms, including phytoseiid mites. Compared with the progress made in the field of insect olfaction, the understanding of how predatory mites perceive chemical compounds and react to their surroundings is merely fragmentarily documented in past decades. In this review, we provide a guide in the field from chemoecology of herbivore-induced plant volatiles (HIPVs) as early as 1980s to the advances made in comparative genomics of predatory mites in 2019. We present from three aspects, i.e., chemosensory-guided feeding behavior, sensory structures and chemoreceptors predicted from genomes. The molecular principles of chemosensory system remain exciting areas for future research, since insights into the mechanisms underlying the sensing of chemical signals will not only contribute to a better understanding of predator behavior and physiology but may also open new avenues for the development of more specific and sustainable approaches to control pests by manipulating behaviors in predators. We then suggest three directions for future research: 1) chemoreceptor gene identification and function verification; 2) neural response circuit to stimuli and 3) application of chemoperception on feeding behavior. The potential methods and techniques are provided as well.

In the last decade, unexpected high temperatures have been frequent in spring and early summer. Numerous studies have shown that such thermal stress has substantial effects on lifehistory traits that influence fitness of insects, but few have examined expression dynamics of heat shock proteins (Hsps) across developmental stages, especially as regards potential carry-over effects at the transcriptional level across metamorphosis. We exposed pupae of the oriental fruit moth ("OFM," Grapholita molesta Busck) to mild heat stress (38°C, 6 h) and then quantified expression patterns of six Hsps (Hsp90, 70, 60, 40, 21, and 11) from pupal through adult stages. Almost all Hsps showed a higher expression immediately after pupae were heat-stressed, but later dropped to normal levels after metamorphosis. Although upregulation of Hsps is transient and the effects carry over longer to early adult stage, upregulation will nonetheless have positive effects on adult fitness. The fitness of some insects may benefit from higher expression of chaperon genes after mild stress, in the form of higher fecundity and longer lifespan, as a carry-over effect. These results suggest that mild thermal stress can change genetic expression that later boosts adult fitness through a cascade effect.