Refugial populations in Quaternary glaciations are critical to understanding the evolutionary history and climatic interactions of many extant species. Compared with the well-studied areas of Europe and Northern America, refugia of species in eastern Asia remain largely unknown. Here, we investigated the phylogeographic history of a globally important insect pest, the oriental fruit moth Grapholita molesta, in its native range of China. Genetic structure analyses unveiled three distinct groups and a set of populations with admixture. Approximate Bayesian Computation (ABC) analyses support range expansion of this moth from southwest groups of Yunnan and Sichuan to northern and eastern China. A set of admixed populations was found around these two ancestral groups. This pattern of genetic structure points to two refugia located in the Yunnan region and Sichuan Basin. The split of the two refugia was dated to 329.2 thousand years ago in the penultimate glacial period. One of the lineages was exclusively found around the Sichuan Basin, indicating the formation of endemic populations in this refugium. Ecological niche model analysis suggested a shrinking distribution from the LIG period to the MID period in the Sichuan lineage but a wide and stable distribution in the other lineage. Our results for the first time suggest that Yunnan and Sichuan jointly served as two large-scale refugia in eastern Asia in Quaternary glaciations, helping to maintain genetic diversity overall.

The barley yellow dwarf virus (BYDV) of cereals is thought to substantially increase the high-temperature tolerance of its aphid vector, Rhopalosiphum padi, which may enhance its transmission efficiency. This is based on experiments with North American strains of BYDV and R. padi. Here, we independently test these by measuring the temperature tolerance, via Critical Thermal Maximum (CTmax) and knockdown time, of Australian R. padi infected with a local BYDV isolate. We further consider the interaction between BYDV transmission, the primary endosymbiont of R. padi (Buchnera aphidicola), and a transinfected secondary endosymbiont (Rickettsiella viridis) which reduces the thermotolerance of other aphid species. We failed to find an increase in tolerance to high temperatures in BYDV-infected aphids or an impact of Rickettsiella on thermotolerance. However, BYDV interacted with R. padi endosymbionts in unexpected ways, suppressing the density of Buchnera and Rickettsiella. BYDV density was also fourfold higher in Rickettsiella-infected aphids. Our findings indicate that BYDV does not necessarily increase the temperature tolerance of the aphid transmission vector to increase its transmission potential, at least for the genotype combinations tested here. The interactions between BYDV and Rickettsiella suggest new ways in which aphid endosymbionts may influence how BYDV spreads, which needs further testing in a field context.

The tree-of-heaven trunk weevil, Eucryptorrhynchus brandti (Harold) (Coleoptera: Curculionidae), is one of the most harmful pests that damage the tree of heaven, Ailanthus altissima Swingle (Sapindales: Simaroubaceae). Aggregation behavior tests of E. brandti adults were conducted in laboratory conditions. The effects of temperature and light on the aggregation behavior of adults were tested, and the effect of sex and host was conducted with binomial choice experiments. The results showed that (1) the adults aggregate in both light and dark environments but preferred the dark environment, (2) temperature can drive the aggregation of E. brandti adults, (3) host plants could trigger E. brandti adults’ aggregation behavior, which is probably related to phytochemicals and insect feeding and localization, (4) there was mutual attraction of males and females and chemical attraction of crude intestinal extracts of males and females, and (5) aggregation behavior of E. brandti adults may also be related to the mediating of physical signals in insects. In this study, aggregation behavior can help us understand conspecific interactions and discover some strategies for effective control.

Moths of the family Tortricidae (Insecta: Lepidoptera) usually distribute in temperate and tropical high upland regions. The oriental fruit moth (OFM) Grapholita molesta is a globally important pest of stone and pome fruit from this family. In this study, we assembled a chromosome-level genome for the OFM and conducted a comparative genomic analysis with other lepidopterans. This genome was assembled to 28 chromosomes with a size of 517.71 Mb, an N50 of 19.5 Mb, and a BUSCO completeness of 97.1%. In total, 19968 protein-coding genes were predicted, among which 15269 were functionally annotated. We manually annotated ten gene families for 13 representative genomes from the Lepidopteran. In general, two tortricid moths have a moderate number of detoxification and receptor genes and the lowest number of HSP genes, congruent with their polyphagous dietary and pattern of distribution. However, the OFM has the highest number of P450, I Rs and ORs among all species. Compared to the other tortricid species of the codling moth Cydia pomonella , the OFM has more genes in all gene families. Our results indicate that the high number of some detoxification and receptor genes may be related to the strong adaptation of OFM as a global pest. The high-quality genome of OFM provides an invaluable resource for understanding the ecology, genetics, and evolution of tortricid moths.

Temperature is a critical determinant of development and reproduction in predatory bugs of the genus Geocoris. Here, we examined thermal effects on life-history traits of Geocoris xishaensis Zhou, Cai & Gao (Hemiptera: Geocoridae), a species recently described from Hainan, China. Individuals were reared on embryo-inactivated eggs of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) at six constant temperatures (16, 20, 24, 28, 32, and 36 °C), and developmental duration, survival, and fecundity were recorded. Age-stage, two-sex life tables were constructed, and 60-day population dynamics were projected. Geocoris xishaensis failed to complete a whole generation at 16 °C and 20 °C. Between 24 °C and 36 °C, developmental duration of each stage decreased with increasing temperature. Female fecundity was highest at 32 °C (241.12 eggs) and 28 °C (184.00 eggs). For the total generation period (including the adult preoviposition period), the lower developmental threshold was estimated to be 17.35 °C, with a corresponding thermal constant of 376.42 degree-days. The estimated number of annual generations of G. xishaensis in Hainan ranges from 7.3 to 8.45. The intrinsic rate of increase (r) and finite rate of increase (λ) both peaked at 32 °C, reaching 0.0961 day⁻¹ and 1.1008 day⁻¹, respectively. Sixty-day population projections revealed increasing trends at 28–36 °C. These results indicate that, of the temperatures tested, 32 °C gave the best overall performance, followed by 28 °C; both can therefore be recommended as suitable temperatures for mass rearing.