This review focuses on two potential strategies for pesticide resistance management: mixtures of chemicals with different modes of action, and the optimization of control intensity（i.e., pesticide concentration and the rate of pest exposure to pesticides）. By comparing and re-modeling several theoretical studies, the review elucidates the principles by which these approaches delay resistance evolution and assesses their practical feasibility for pesticide use. The principle underlying mixtures is historically termed “redundant kill,” whereby individuals resistant to one pesticide are eliminated by another. In contrast, the high-dose/refuge strategy in Bt crops delays resistance by applying high concentrations that kill even heterozygotes within treated fields, while maintaining refuges where pests survive regardless of genotype, and utilizing pre-mating dispersal to prevent mating among resistant survivors. Although high doses have been considered impractical for conventional pesticides, a recent dose–response modelling study indicates that mixtures can delay resistance using realistic concentrations（within several times the current label doses）. Furthermore, in mixtures, even without refuges, the fates of the pests within the field are separated into “killed by multiple agents” or “surviving without exposure,” thereby delaying resistance. This proactive containment of resistance alleles contrasts with the postponement of resistance achieved by rotational application.

The establishment of alien species is one of the major causes of biodiversity loss and can have serious impacts on native ecosystems. The Saga Plain is an important area for biodiversity conservation, where many endangered aquatic organisms are distributed. In recent years, the alien freshwater shrimp Palaemon sinensis（Sollaud）（Decapoda: Palaemonidae）has been reported to have invaded domestic freshwater ecosystems in Japan and is suggested to have displaced a native congener, Palaemon paucidens De Haan, at various localities. In this study, we investigated the distribution of these species in the Saga Plain. As a result, P. sinensis was found widely in the central and southern parts of the Saga Plain. In these areas, P. paucidens was not found at most localities, suggesting that the alien species is replacing the native species. Based on monthly surveys of body size and ovigerous individuals, P. sinensis reproduces once in the spring.

Panonychus osmanthi Ehara et Gotoh—a species closely related to the citrus red mite, Panonychus citri—occurs on sweet osmanthus. Satsuma mandarins are poor hosts for P. osmanthi in terms of the development status and egg production, and P. citri cannot develop on sweet osmanthus. Therefore, P. osmanthi-infested sweet osmanthus plants are likely to serve as sites for the preservation of the natural enemies of P. citri in citrus orchards. We investigated the growth status of sweet osmanthus as a windbreak hedge and the occurrence of P. osmanthi and its natural enemies. The young sweet osmanthus trees grew into a windbreak hedge 5 years after being planted. Panonychus osmanthi was found to be widely distributed on sweet osmanthus in parks and on roadsides. Common natural enemies of P. citri and P. osmanthi—predaceous insects and phytoseiid mites—occurred on the sweet osmanthus. When citrus and sweet osmanthus were planted close to each other, the mite occurrence patterns on both types of trees were nearly identical, but the peak period of P. osmanthi density on sweet osmanthus sometimes occurred slightly earlier than that of P. citri on citrus trees. These results suggest that sweet osmanthus windbreak trees function as sites for the preservation of native natural enemies in citrus orchards.

Stenotus rubrovittatus（Matsumura）（Heteroptera: Miridae）is a serious pest that causes pecky rice grains by sucking out the contents of developing rice kernels. Because the adult S. rubrovittatus migrates to rice paddy fields during the heading stage, the occurrence of this pest in the paddy fields is likely to depend on the heading date of the rice. This study investigated the heading dates of rice and the peak occurrence dates of S. rubrovittatus adults in several rice paddy fields in Ibaraki Prefecture from 2021 to 2024. The occurrence peak of the adults in each paddy field was then predicted by using a developmental-rate-type（DVR-type）phenological model of rice. The DVR-type model predicted the occurrence peak of S. rubrovittatus adults more accurately than the traditional effective accumulated temperature model for insects, with a root mean square error of 1.59 days, a mean absolute error of 0.84 days, and an R² value of 0.77. These results demonstrate the effectiveness of the DVR-type phenological model in predicting the occurrence peaks of S. rubrovittatus in rice paddy fields.