Development of an effective hydrogel bait and an assessment of community-wide management targeting the invasive white-footed ant, Technomyrmex brunneus.

BACKGROUND: Ants are one of the most serious household pests. White-footed ants in the genus Technomyrmex (Hymenoptera: Formicidae) are invasive species of increasing global importance as evidenced by recent range expansion, nuisance pest status in residential areas and control difficulties driven mainly by lack of effective bait products. The goal for the current study was to develop an effective hydrogel bait and community-wide management program for controlling the invasive T. brunneus in a residential area of Hachijo Island, Japan. RESULTS: In laboratory insecticide screening, hydrogel baits containing thiamethoxam achieved higher T. brunneus mortality than those containing dinotefuran, imidacloprid, boric acid or fipronil at the concentrations tested. Hydrogel baits containing 0.01% and 0.001% thiamethoxam resulted in ≥90% mortality within seven days. However, the horizontal transfer effect was not strong with either concentration. Field experiments confirmed that hydrogel baits containing 10% and 30% sugar are highly attractive to T. brunneus. The community-wide treatment utilizing hydrogel bait containing 0.001% thiamethoxam and 30% sugar significantly suppressed T. brunneus. Town residents were given the opportunity to participate in the program by applying hydrogel baits around their homes, and a follow-up survey revealed that the residents regarded hydrogel baits as easy to apply and highly attractive and effective against T. brunneus. CONCLUSION: The hydrogel bait and management program developed in this study can be used to suppress T. brunneus. Furthermore, our results demonstrate that a large network of highly motivated and properly trained members of the public can be highly effective in managing invasive ant populations. © 2022 Society of Chemical Industry.

Revision of Taiwanese and Ryukyuan species of Pristepyris Kieffer, 1905, with description of a new species (Hymenoptera, Bethylidae).

The pristocerine genus Pristepyris comprises 38 valid species recorded worldwide, except in the Australian Region. Of them, three species, namely P.mieae (Terayama, 1995), P.tainanensis (Terayama, 1995) and P.takasago (Terayama, 1996), have been recorded from Taiwan and three species, i.e. P.ishigakiensis (Yasumatsu, 1955), P.minutus (Yasumatsu, 1955) and P.ryukyuensis (Terayama, 1999), from the Ryukyus in Japan. In the present study, the species-level classification of both Taiwanese and Ryukyuan species of Pristepyris was revised using newly-collected specimens by the external and male genital morphological as well as molecular phylogenetic analysis. Overall, six species of Pristepyris were recorded from Taiwan and the Ryukyus. Among these, five were previously recorded for the region and were revised here: P.ishigakiensis, P.mieae, P.ryukyuensis, P.tainanensis and P.zhejiangensis. Additionally, a new species, P.seqalu sp. nov., is herein described and illustrated. Furthermore, the species P.minutus is transferred to Eleganesia and P.takasago is synonymized under P.minutus. Due to the new combination of Pristepyrisminutus, a key to Taiwanese and Ryukyuan species of the genus Eleganesia, based on male morphology, is provided in Appendix 1. We confirmed for the first time the correspondence between the male and female species of P.zhejiangensis by molecular data. High compatibility in species delimitation patterns, suggested by the morphological and molecular phylogenetic approaches, highlighted the significance of the former approach for accurately classifying aged voucher specimens of Pristocerinae in public collections.

Ultramorphological Characteristics of Falsogastrallus sauteri Pic (Coleoptera: Ptinidae) and a New Species of Cephalonomia Westwood (Hymenoptera: Bethylidae): A Book-Boring Beetle and Its Natural Enemy in Taiwan.

Libraries are invaluable resources, documenting significant events that have shaped human history. However, the preservation of old books is severely threatened by insects commonly referred to as bookworms. In this study, a sample of infested books in a historic library in Taiwan was randomly selected and examined. An anobiid book-boring beetle, Falsogastrallus sauteri Pic, 1914 (Coleoptera: Ptinidae) was identified as the major bookworm species present. To facilitate its identification, both adults and larvae of F. sauteri are redescribed, with emphasis on its ultramorphological characteristics as revealed by scanning electronic microscopy. Furthermore, an undescribed parasitoid wasp in the Bethylidae was discovered in the frass, holes and tunnels created by F. sauteri. The new species, Cephalonomia formosiensis sp. nov. is described, and we suggest that it probably uses F. sauteri as host.

Revision of Taiwanese and Ryukyuan species of Propristocera (Hymenoptera: Bethylidae), with description of a new species.

The genus Propristocera Kieffer was very recently revived from the synonymy of the genus Apenesia Westwood, and consists of a total of 25 valid species recorded from the Afrotropical, Oriental and Palaearctic regions. Only two of its species, P. formosimonticola and P. pingtungensis, have been previously recorded from Taiwan. In this study, we examined species of Propristocera collected from Taiwan and the Ryukyus based on external morphology, male genital morphology and molecular phylogenetic analyses, gene markers: nuclear 28SrDNA, mitochondrial COI. In consequence, four species were recognized. Propristocera okinawensis had its record expanded from the Ryukyus to Taiwan, whereas P. kusigematii previously known from the Ryukyus was synonymized under P. pingtungensis, which was known from Taiwan. Furthermore, one new species, Propristocera seediq sp. nov., was discovered in Taiwan and the Ryukyus.

Redefinition of the genus Bannapone and description of B. cryptica sp. nov. (Hymenoptera: Formicidae: Amblyoponinae).

The ant genus Bannapone was established by Xu in 2000 and has been recognized as one of the rarest ant genera in the world. In the course of our careful examination of Asian species of Stigmatomma, we have found that the following Stigmatomma species share a unique morphological characteristic in mandibular dentition with Bannapone mulanae and B. scrobiceps: Stigmatomma caliginosum (Onoyama, 1999), Stigmatomma fulvida (Terayama, 1987), S. pertinax (Baroni Urbani, 1978), S. zwaluwenburgi Williams, 1946 and an unnamed species "Stigmatomma sp. eg-3". In the present paper, we redefine Bannapone, describe "Stigmatomma sp. eg-3" as a new species of Bannapone, and transfer S. caliginosum, S. fulvida, S. pertinax and S. zwaluwenburgi Williams, 1946 to Bannapone.

Discovery of the genus Formosiepyris Terayama, (Hymenoptera, Bethylidae) in Vietnam, with a description of a new species.

Formosiepyrisvietnamensis sp. n. (Hymenoptera: Bethylidae) is described based on material collected from Da Lat, southern Vietnam. This is the first record of Formosiepyris Terayama from Vietnam. The new species can be distinguished from other Formosiepyris species by a narrow and rounded clypeus; a mandible with three teeth; a second metasomal tergite having small, sparsely distributed punctures and smooth interspaces, except for anterior 2/5, which is microreticulate; and a head length : width aspect ratio of 10 : 11. A key to the Oriental species of Formosiepyris is provided.

Combined use of a synthetic trail pheromone and insecticidal bait provides effective control of an invasive ant.

BACKGROUND: Except for sex pheromones, use of pheromones in pest management has been largely unexplored. A high concentration of trail pheromone disrupts ant trail following and foraging, and thus synthetic trail pheromone can be a novel control agent for pest ants. In this study, a year-long treatment of small areas (100 m(2) plots of urban house gardens) with synthetic trail pheromone, insecticidal bait or both was conducted to develop a novel control method of the invasive Argentine ant Linepithema humile (Mayr). RESULTS: The ant population could be maintained lower than or similar to the initial level only by combined treatment with synthetic trail pheromone and insecticidal bait. Actually, the ant population was nearly always lowest in combination treatment plots. Throughout the study period, the ant population in plots treated with either one of synthetic trail pheromone or insecticidal bait remained similar to no-treatment plots. CONCLUSIONS: Combination treatment may be a more effective and environmentally friendly method for controlling invasive ants than conventional methods. Extermination of ants by insecticidal bait and inhibition of re-infestation by pheromone may be the mechanism of the combination effect. This is the first study to show a significant effect of synthetic trail pheromone on ant population.

Workers select mates for queens: a possible mechanism of gene flow restriction between supercolonies of the invasive Argentine ant.

Some invasive ants form large networks of mutually non-aggressive nests, i.e., supercolonies. The Argentine ant Linepithema humile forms much larger supercolonies in introduced ranges than in its native range. In both cases, it has been shown that little gene flow occurs between supercolonies of this species, though the mechanism of gene flow restriction is unknown. In this species, queens do not undertake nuptial flight, and males have to travel to foreign nests and cope with workers before gaining access to alien queens. In this study, we hypothesized that male Argentine ants receive interference from workers of alien supercolonies. To test this hypothesis, we conducted behavioral and chemical experiments using ants from two supercolonies in Japan. Workers attacked males from alien supercolonies but not those from their own supercolonies. The level of aggression against alien males was similar to that against alien workers. The frequency of severe aggression against alien males increased as the number of recipient workers increased. Cuticular hydrocarbon profiles, which serve as cues for nestmate recognition, of workers and males from the same supercolony were very similar. Workers are likely to distinguish alien males from males of their own supercolony using the profiles. It is predicted that males are subject to considerable aggression from workers when they intrude into the nests of alien supercolonies. This may be a mechanism underlying the restricted gene flow between supercolonies of Argentine ants. The Argentine ant may possess a distinctive reproductive system, where workers participate in selecting mates for their queens. We argue that the aggression of workers against alien males is a novel form of reproductive interference.

Intraspecific variation of cuticular hydrocarbon composition in Formica japonica Motschoulsky (Hymenoptera: Formicidae).

Cuticular hydrocarbons and morphological features were compared among 80 Formica japonica colonies collected in Japan. Although a few morphological differences were found in workers among the colonies, four different types of cuticular hydrocarbon composition were observed. This was supported by a principal component analysis. We further compared the cuticular hydrocarbons among a total of approximately 400 F. japonica colonies, and categorized the hydrocarbon components into four types based on the result of discriminant analyses for the first 80 colonies. Type 1 was observed in colonies mainly collected in southern Honshu, Shikoku, and Kyushu. Types 2, 3, and 4 were from colonies with primary collections in Southern Honshu, central and Pacific coast northern Honshu, and the Sea of Japan coasts of northern Honshu and Hokkaido, respectively. The occurrence of four distinct types of CHC composition suggests that the colonies that produce them are separate species.