The predatory miteNeoseiulus barkeri(Acari: Phytoseiidae) is typically used for biocontrol ofTetranychus urticaeon strawberries. However, its biological characteristics are greatly affected by temperature in hot summer days. In this study, the influence of different short‐term heat stresses on the functional response and prey consumption of unmated female ofN. barkerion three stages (egg, protonymph and adult) ofT. urticaewas evaluated. Three temperatures (38, 40 and 42°C), three short‐term heat duration (2, 4 and 6 hr), eight prey densities (3, 6, 9, 12, 15, 18, 21 and 24 individuals), (85 ± 5) % RH and a 16‐hr: 8‐hr (L:D) photoperiod were used during a 24‐hr period in functional response experiments. The results showed that the eggs ofN. barkericould not hatch at 42°C and the type II functional response was determined for adult females ofN. barkeriat all treatments by using the logistic regression analysis. TheN. barkerihad the highest attack rate of 1.029, 2.044 and 0.913 hr^‐1for three stages ofT. urticaeat 25°C and the lowest value of 0.585, 0.973 and 0.498 hr^‐1at 40°C, 6 hr. On the contrary, the handling time of the predator prolonged when the temperature increased from 25°C to 40°C and the maximum level was observed at 40°C, 6 hr (0.126, 0.153 and 0.172 hr). Our study indicated that the effects of short‐term heat stress were negative on the predation ability ofN. barkeriand heat stress should be avoided as much as possible to achieve the best predation and control effect ofN. barkeriin indoor rearing and field release.

Phytoseiid mite Neoseiulus barkeri is a crucial biological control agent utilized to control pest mites and many insects in crops all over the world. However, they are vulnerable to multiple environmental pressures, with high-temperature stress being the most significant challenge. Heat stress disrupts the balance of reactive oxygen species (ROS) levels in organisms, resulting in oxidative stress within the body. Antioxidant enzymes play a crucial role in effectively neutralizing and clearing ROS. In this study, comparative transcriptomics and quantitative real-time PCR (qRT-PCR) were employed to assess the impact of short-term heat stress on the transcript expression of antioxidant enzyme genes in N. barkeri. We primarily identified four antioxidant enzyme genes (NbSOD, NbPrx, NbCAT, and NbGPX) in N. barkeri after exposure to short-term heat stress. Then, new data on the expression patterns of these genes were generated. RNA sequencing and bioinformatics analysis revealed that NbSOD belongs to the Fe/Mn family of superoxide dismutase (SOD), which was identified as MnSOD. NbPrx was classified as a 1-Cys peroxiredoxin of the peroxidase family, whereas NbCAT was recognized as a classical catalase, and NbGPX was determined as cytoplasmic glutathione peroxidase-1 (GPX1). Transcriptional expression analysis of these four genes was conducted at different high temperatures: 36 °C, 38 °C, and 40 °C for 2, 4, and 6 h. The results also showed that all four genes exhibited significant up-regulation in response to short-term heat stress. Similarly, the highest expression levels for NbSOD, NbPrx, and NbCAT were observed at 40 °C for 4 h. However, NbGPX displayed its maximum expression value at 38 °C for 4 h. Overall, the obtained data suggest that short-term heat stress increases levels of ROS generated inside living organisms, which disrupts the oxidative balance and leads to alterations in the expression levels of antioxidant enzyme genes.

Tetranychus urticae, a globally ubiquitous mite, poses a significant threat to agriculture. Elevated temperatures exacerbate the growth, development, and reproduction of T. urticae, leading to substantial crop damage. In this study, we employed comparative transcriptomic approaches with whole-genome information of T. urticae to identify six Glutathione S-transferase genes (GSTs) implicated in heat stress response. Through comprehensive bioinformatics analyses, we elucidated the tertiary structure and active sites of the corresponding proteins, providing a thorough characterization of these GST genes. Furthermore, we investigated the expression patterns of these six GST genes under short-term heat shock conditions. Our findings unveiled the involvement of T. urticae GST genes in combating oxidative stress induced by heat, underscoring their role in antioxidant defense mechanisms. This study contributes valuable insights into the molecular mechanisms underlying the response of T. urticae to heat stress, laying a foundation for the development of strategies aimed at mitigating its impact in high-temperature environments.