Two new species and a key to species of the genus Eumenes Latreille(Hymenoptera:Vespidae:Eumeninae) from southwestern China

Two new species, Eumenes ferrugiantennus sp. nov. from Yunnan and E. nigriscutatus sp. nov. from Chongqing and Sichuan, China, are described. A key to the species in this genus from southwestern China is provided. Types of the new species are deposited in the Institute of Entomology and Molecular Biology, Chongqing Normal University.

沙湖自然保护区胡蜂科昆虫多样性研究

于2011年5～10月,通过随机网捕的方法对宁夏沙湖自然保护区的胡蜂科（Vespidae）昆虫进行了系统调查,共获得胡蜂总科昆虫标本91号,隶属于3科10属14种。中华长脚马蜂（Polistes chinesis antennalis）、北方黄胡蜂（Vespula rufa）、基蜾蠃（Eumenes pedunculatus pedunculatus）个体数量最多,共占总数量的76.9%,分别占总数量的61.5%、9.9%、5.5%。中华长脚马蜂是沙湖自然保护区中胡蜂总科的优势种。区系组成分析结果显示古北界种类有3种,东洋界有3种。在我国地理区划中华北成分和华中成分占优,蒙新区与西南区数量差不多,东北较蒙新区占优势,按区系相关性从近到远排列依次为华北/华中、东北、蒙新/西南、华南、青藏。区系型的组成方式共8种,其中无单区型、双区型5种、三区型7种、四区型2种。

Foraging behavior related to habitat characteristics in the invasive wasp Vespula germanica

When foraging on carrion resources, the wasp Vespula germanica usually makes repeated visits to the feeding site until depleting the resource. In the present study we analyzed how environmental cues affect wasps＇ behavior when re-locating a protein food source. We studied this behavior in two different natural habitats： closed and open habitats. As closed habitats have more references to orient wasps to the feeding site than open habitats, we hypothesized that they would return to the foraging site more frequently in closed habitats than in open ones. We tested this hypothesis by studying wasp behavior in three different natural habitat conditions： （i） closed habitats, （ii） open habitats, and （iii） open habitats artificially modified by adding five sticks with flagging. Experiments consisted of training individual wasps to feed from a certain array, and at the testing phase we removed food and displaced the array by 60 cm. Therefore, we recorded wasps＇ choices when returning to the training area, by counting both the wasps＇ first approaches and the number of visits to the original feeding site and the displaced array. Wasps＇ behavior while re-locating a protein food source was different if foraging at open or closed habitats. Wasps more frequently re- visited a previous feeding location when foraging in closed habitats than when foraging in open ones. Furthermore, wasps more frequently visited the displaced array than the original feeding site in all three treatments. Nevertheless, when wasps were trained in closed habitats, they returned to the original feeding site more frequently than if trained in open ones. Interestingly, when five sticks with flagging were added in open habitats, wasps responded similarly as in closed habitats without these references. The results show that foraging behavior in V. germanica seems to be different in closed and open habitats, probably associated with the existence of references that guide foragers when re-locating undepleted resources

Behavioral syndrome in a native and an invasive hymenoptera species

Recent studies have focused on the role of behavior in biological invasions. Individuals may differ consistently in time for several behavioral traits （personality） which covary （behavioral syndrome） resulting in different behavioral types, some of them favoring invasion. Social hymenopterans have a strong potential to be invaders and their success depends primarily on the foundresses＇ ability to found viable colonies. They are expected to be active, explorative and bold for optimally establishing their nest. In Europe, 2 homet species coexist： the native Vespa crabro and the invasive Vespa velutina. These 2 species may compete for nesting sites and we suggest that the initial success of V. velutina has been favored by its behavior in outperforming V. crabro for the traits involved in nest initiation. Here, we （i） defined the personality of V. crabro and V：. velutina, （ii） tested for the existence of behavioral syndrome in these species, and （iii） compared their performances using an open-field test. Our results show that V. crabro foundresses behave consistently but not V. velutina; this lack of consistency being mainly due to reduced variance among individuals. This result questions the possibility of detecting consistent behavioral differences in species having recently undergone a strong bottleneck. Both species exhibit the same correlations between activity, boldness and exploration and V. velutina clearly outperforms 14. crabro for all traits. Our results suggest that activity, boldness, and exploration are implicated in both hornet nest initiation and invasion process which contributed to explain why social hymenopterans are so successful at colonization.

Delayed sexual maturity in males of Vespa velutina

Vespa velutina var nigrithorax （Lepelletier, 1835） is an invasive predator of bees accidentally introduced in France in 2004, and it is having a serious impact on apiculture and ecosystems. Studying the reproduction of an invasive species is key to assess its population dynamic. This study explores the sexual maturation of IT. velutina males and the evolution of their fertility. The main studied parameters were physiologic （spermiogenesis, spermatogenesis） and anatomic （testes size and structure, head width）. Two populations of males were described based on their emergence period： early males in early summer or classic males in autumn. Each testis has an average of 108 testicular follicles. Spermatogenesis is synchronous, with only 1 sperm production wave, and completed, on average, at 10.3 d after emergence with the degeneration of the testes. The sperm counts in seminal vesicles of mature males are 3 x 106 in October/November and 0.8 ~ 106 in June. In com- parison, females store 0.1 x 106 sperm in their spermathecae. The early males emerged from colonies made by fertilized queens. The reproductive potential of these early males seemed limited, and their fimction in the colony is discussed. The sperm stock evolution in autumn males suggests the occurrence of a reproductive pattern of male competition for the access to females and a single copulation per male. The synchronicity of male and foundress emergences and sexual maturation is of primary importance for the mating success and the future colony development.

Spatial distribution of Vespa velutina individuals hunting at domestic honeybee hives： heterogeneity at a local scale

Since its recent introduction into Europe, the yellow-legged hornet, Vespa velutina, has become a major predator of the domestic honeybee, Apis mellifera, but little is known about its hunting behavior. We studied V. velutina hunting behavior by a capture- mark-recapture procedure in an experimental apiary. A total of 360 hornets were captured and tagged, and we determined： （i） the number of hornets visiting the apiary and the changes in time, （ii） the average number of individual visits per half-day and the time elapsed between consecutive recaptures, and （iii） the individual and global distribution of the hornets in the apiary. More than 50% of the marked hornets were recaptured at least once, this increased to 74% in considering the first marked individuals. We estimated 350 hornets visiting the patch daily with at least 1 visit per half-day. The number of marked hornets decreased over time while the number of unmarked ones increased, suggesting a turnover of individuals. The reduction of the delay between consecutive visits indicates that hornets became more efficient over time. Most of the hornets （88%） were recaptured in front of different hives but, overall, the global distribution was aggregative. Hornets were mainly recaptured in front of 1 hive which was neither the smallest nor the biggest colony, suggesting that the major cue used by hornets is not the amount of food. We hypothesize that the defensive behavior of the honeybee colony could explain our results which may be promising to further studies.