Sexual Size Dimorphism and Aggressive Interactions under Starvation Conditions in the Seed Bug Togo hemipterus (Heteroptera: Lygaeidae)

Males of the seed bug Togo hemipterus are larger in size and have considerably larger front legs compared to females. This size discrepancy is likely related to the fact that males fight for food using their enlarged forelegs. A "hungry" bug, i.e. one previously without food, is expected to behave in a certain way when food is present. Here, we demonstrate that aggressive "fighting and chasing" behavior was frequently observed only between males under starvation conditions and became especially severe when food was present. Togo hemipterus males may adopt a resource-defense mating system that is beneficial for males because females aggregate near food when it is scarce. This strategy strongly suggests that the aggressive behavior acts as male–male competition. In a second set of experiments, aggressive behavior occurred between two small males, two large males, or one large and one small male. Fighting ensued mainly when large males were involved, and larger males won fights. Consequently, the male-biased sexual size dimorphism in T. hemipterus appears to be partially attributable to sexual selection favoring larger males

Prey size affects the costs and benefits of group predation in nymphs of the predatory stink bug Andrallus spinidens (Heteroptera: Pentatomidae)

Group predation promotes foraging efficiency because it increases the size of prey that can be killed and improves hunting success compared to solitary predation. However, group predation may increase competition among group members during feeding. Earlier studies have focused on the advantages of group predation, but little is known about the costs and benefits of group predation for individual members of the group. Here, we show that the costs and benefits of group predation for individuals of the predatory stink bug Andrallus spinidens vary with prey size in laboratory experiments. We found that when A. spinidens fed on small prey, group predation did not significantly increase foraging efficiency but did increase competition for food among group members. In contrast, when prey was large, group predation promoted foraging efficiency, and competition over food was not detected. Our results suggest that group predation by A. spinidens nymphs is advantageous for individual members because it enables each member to hunt larger prey that could not be hunted alone. However, when group size was large or prey size was small, group predation increased competition among group members

The eradication projects and preventative control of quarantine pests in Okinawa, Japan

Of the several exotic insect species in Japan, five quarantine plant pest taxa: the oriental fruit fly, Bactrocera dorsalis complex, the melon fly, Zeugodacus cucurbitae, the solanaceous fruit fly, Bactrocera latifrons, the sweet potato weevil, Cylas formicarius, and the West Indian sweet potato weevil, Euscepes postfasciatus, have been targeted in eradication programs using the male annihilation technique (MAT) and/or the sterile insect technique (SIT). Although all targeted fruit flies have successfully been eradicated, the incidences of re-invasion by Bactrocera dorsalis complex have been increasing in recent years, indicating the necessity for reinforcement and improvement of countermeasures for fruit fly re-invasion and/or recolonization. The program targeted at C. formicarius achieved the goal of complete eradication in Kume Island. The program for E. postfasciatus has yet to achieve eradication, even though it was initiated at the same time as that for C. formicarius. Major technical improvements are required for successful eradication of E. postfasciatus

First case of successful eradication of the sweet potato weevil, Cylas formicarius (Fabricius), using the sterile insect technique.

This paper presents the first case of the successful eradication of a Coleoptera pest species over a wide area using a combination of male annihilation technique (MAT) and sterile insect technique (SIT) application. The sweet potato weevil, Cylas formicarius, is one of the most destructive and widely distributed pests of sweet potato, Ipomoea batatas. A project to eradicate it was launched in 1994 on Kume Island, Okinawa Prefecture, Japan. The MAT application was first used from November 1994 to January 1999 to reduce the density of wild populations. The distribution and densities of weevils were assessed by trapping them and surveying infestation rates in wild hosts and sweet potatoes in the field. The C. formicarius populations were suppressed by approximately 90% and plant infestations were reduced from 9.5% to less than 0.1% by using the MAT. Then, hundreds of thousands to millions of sterile weevils were released each week (ca. 460 million in total from 1999 to 2012). As a result, based on an analysis of 12748 stems and 48749 tubers, no weevil infections were detected in the stems or tubers of sweet potato since 1997. Since 2009, almost no wild weevils were captured in traps, and in wild host and sweet potato surveys no weevils have been found in any of the 580 locations and 8833 samples since October 2011. As of 28 December, 2012, C. formicarius is considered to have been eradicated from Kume Island. This paper describes the process of eradicating C. formicarius using SIT application integrated with MAT application for the first time and discusses some of the main challenges associated with the weevil eradication campaignl

Genotypes of the invasive ant Brachyponera chinensis in its native and introduced ranges

Genotypes of the invasive ant Brachyponera chinensis in its native and introduced ranges. The dataset contains samples names, locations, castes and genotypes at 20 microsatellite loci

Sequence_COI_EYER

Mitochondrial sequences of the Cytochrome oxidase 1 marker for the invasive ant species Brachyponera chinensis in its native and introduced ranges

Data from: Inbreeding tolerance as a pre-adapted trait for invasion success in the invasive ant Brachyponera chinensis

Identifying traits that facilitate species introductions and successful invasions of ecosystems represents a key issue in ecology. Following their establishment into new environments, many non-native species exhibit phenotypic plasticity with post-introduction changes in behavior, morphology or life history traits that allow them to overcome the presumed loss of genetic diversity resulting in inbreeding and reduced adaptive potential. Here we present a unique strategy in the invasive ant Brachyponera chinensis (Emery), in which inbreeding tolerance is a pre-adapted trait for invasion success, allowing this ant to cope with genetic depletion following a genetic bottleneck. We report for the first time that inbreeding is not a consequence of the founder effect following introduction, but it is due to mating between sister queens and their brothers that pre-exists in native populations which may have helped it circumvent the cost of invasion. We show that a genetic bottleneck does not affect the genetic diversity or the level of heterozygosity within colonies and suggest that generations of sibmating in native populations may have reduced inbreeding depression through purifying selection of deleterious alleles. This work highlights how a unique life history may pre-adapt some species for biological invasions