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 revisited 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.     

蜜蜂嗡嗡吓跑植物害虫

人类失去蜜蜂,世界将会怎样？这些小昆虫为我们带来蜂蜜,并且在全世界为数以百计的粮食作物授粉。研究人员如今发现,蜜蜂在保障人类的粮食安全方面还扮演了一个重要角色——它们发出的嗡嗡声能够保护庄稼和其他植物免遭甜菜黏虫的侵袭。植物的叶、花和果实都能成为甜菜黏虫的食物。但是甜菜黏虫也有自己的天敌：黄蜂。为了防范黄蜂,甜菜黏虫进化出了感觉毛——能够感知黄蜂拍打翅膀所产生的空气震动。     

Influence of host age and host deprivation on longevity, egg load dynamics and oviposition rate in Microplitis rufiventris

Adult size, longevity, egg load dynamics and oviposition ofMicroplitis rufiventris Kok. which began their development in the first, second, third （preferred hosts） or fourth （non-preferred hosts） instar larvae of Spodoptera littoralis （Boisd.） were studied. The parasitoid size was largely determined by the initial host size at parasitism. Non-ovipositing females derived from older hosts lived for longer periods than those derived from younger ones. However, the ovipositing females, irrespective of their size, lived for almost the same periods. At emergence, the oviducts of adult females contain a significant amount of mature eggs available for oviposition for a few hours on eclosion day. Egg load increases during the early phase of adult life. The amount of additional mature eggs and rate of egg maturation per hour was greater for wasps derived from preferred hosts compared with those in females derived from non-preferred hosts. The pattern of egg production in M. rufiventris females depended on the availability of hosts for parasitization. Host-deprived females depleted the egg complement with aging; the longer the host deprivation, the lower the oviduct egg load. Marked reduction in both realized or potential fecundity of host-deprived females was observed following host availability. Host privation for more than 3 days induced a marked deficit fecundity pattern through the female＇ s life. The realized fecundity was determined by the interaction among host availability, the number of eggs that are matured over the female＇ s life span, oviposition rate and host size from which the female was derived. These results suggest that： （i） M. rufiventris wasp is a weak synovigenic species; （ii） the maturation of additional eggs is inhibited once the maximum oviduct egg load is reached; （iii） the egg load of the newly emerged female is significantly less than the realized fecundity; and （iv） because M. rufiventris females oviposit fewer eggs when they begin depleting their egg supply at 3 days, augmentative releases will require release immediately following emergence to ensure the highest parasitization rate in the field.     

蛇伤胶囊治疗黄蜂蜇伤临床疗效观察

目的观察蛇伤胶囊治疗黄蜂蜇伤的临床疗效。方法将321例黄蜂蜇伤患者随机分为两组,对照组158例采用局部处理、抗感染、注射破伤风抗毒素、应用糖皮质激素、保护胃黏膜、改善细胞代谢及对症处理等治疗;治疗组163例在对照组治疗的基础上加用蛇伤胶囊治疗。比较两组患者治疗前、后的中医证候积分,并进行临床疗效评价。结果治疗前两组患者的中医证候积分无显著差异（P〉0．05）,治疗后两组患者中医证候积分差值比较有显著性差异（P〈0．01）;两组的临床疗效比较差异显著（P〈0．05）。结论蛇伤胶囊可以改善黄蜂蜇伤患者的临床症状,提高临床疗效。     

The influence of past experience on wasp choice related to foraging behavior

Memory has been little studied in social wasps. Vespula germanica （Fab.） （Hymenoptera： Vespidae） frequently revisits nondepleted food sources, making several trips between the resource and the nest. In this study, we analyzed this relocating behavior in order to evaluate whether this species is capable of remembering an established association after 1 h. To this end, we trained wasps to feed from a certain array. Then it was removed, setting it up again 1 h later, but this time 2 baited feeders were put in place, one at the original feeding site and the other opposite the first. We recorded the proportion of returning foragers, and their choice of feeder, after either 1 or 4 feeding trials. After 1 h, 78% of wasps trained with 4 feeding trials and 65% trained with 1, returned to the experimental area. Furthermore, during the testing phase, wasps trained with 4 feeding trials collected food from the previously learned feeder significantly more frequently than from the nonlearned one （P 〈 0.05）. In contrast, wasps that had been trained only once chose both feeders equally. Thus, memory retrieval could be observed 1 h after wasps had collected food on 4 consecutive occasions, but not after only 1. To our knowledge, this is the first study showing that V. germanica is capable of remembering an association 1 h after the last associative event, demonstrating that 1 h does not impair memory retention if4 feeding experiences have occurred.     

Seasonal Changes in the Trade-off Among Fig-supported Wasps and Viable Seeds in Figs and Their Evolutionary Implications

Abstract: What the real trade-off is among fig-supported wasps and the viable seeds of figs is heatedly debated in the studies of fig/fig wasp mutualism. In the present study, we collected wasp offspring (galls) and the viable seeds of premature fruits, and determined the foundress number in receptive fruits and all the types of wasps supported by Ficus racemosa L. during both the rainy and dry seasons in Xishuangbanna, China. The data show that the galls were positively correlated with viable seeds ( n = 32; r = 0.74; P < 0.001) when the proportion of vacant female flowers (PVFF) was high, in April (68.0%), and were negatively correlated with viable seeds ( n = 48; r =−0.59; P < 0.05) when PVFF were limited (PVFF = 42.6%) during a colder month (January). The mean foundress number per fruit during the colder months is significantly lower than during the warmer months ( F _{5, 603}= 27.9; P < 0.001) and pollinator wasps can live longer during the colder months. During the colder months, the proportions of non-pollinators and wasp offspring are higher than those found during other months, whereas the proportion of viable seeds is not different compared with that of other months. Non-pollinator wasps tend to oviposit the female flowers that have been oviposited by pollinator wasps. The non-pollinators only negatively affect pollinator wasps and there is no obvious negative effect of non-pollinator wasps on viable seeds, so ovipositing by non-pollinator wasps will not result in the extinction of the figs during the process of evolution. The results of the present study indicate that figs can allow less foundresses to be in fruit cavities when PVFF are limited, which provides supporting evidence for the previous assumption that the plants have developed a mechanism to maintain a stable system because of the conflicts between the parties involved.
(Managing editor: Ya-Qin HAN)     

Fragmentation Effects on Diversity of Wasp Community and Its Impact on Fig／Fig Wasp Interaction in Ficus racemosa L.

Habitat fragmentation usually results in alteration of species composition or biological communities. However, little is known about the effect of habitat fragmentation on the fig/fig wasp system.In this study, we compared the structure of a fig wasp community and the interaction between figs and fig wasps of Ficus racemosa L. in a primary forest, a locally fragmented forest and a highly fragmented forest.Our results show that, in the highly fragmented forest, the proportion of pollinator wasps is lower and the proportion of non-pollinator wasps is higher compared with the primary forest and locally fragmented forest. The proportion of fruits without pollinator wasps in mature fruits is also greatly increased in the highly fragmented forest. The proportion of galls in all female flowers increases in the highly fragmented forest, whereas the proportion of viable seeds does not change considerably. The disruption of groups of fig trees results in a decrease in pollinator wasps and even might result in the extinction of pollinator wasps in some extreme cases, which may transform the reciprocal interaction between figs and fig wasps into a parasite/host system. Such an effect may lead to the local extinction of this keystone plant resource of rain forests in the process of evolution, and thereby, may change the structure and function of the tropical rain forest.     

共生菌可保护黄蜂免受真菌侵害

研究者发现了一种黄蜂和新发现细菌种之间的有趣的共生关系,而这种关系将有助于了解高等生物体防御其他微生物的防御机制。欧洲狼蜂,一种地面筑巢的黄蜂,链霉菌以一种特殊的方式共生于它的触角中,雌性黄蜂则用这些共生细菌来保护黄蜂幼虫免受致病真菌的侵害。     

Biodiversity of vespid wasps in spatial and temporal dimensions in northern Zanjan Province of Iran

Vespidae is one of the major families of Hymenoptera with more than 115000 described species. In the present paper, Simpson and Shannon-Wiener diversity indices, Simpson,Camargo, Smith and Wilson, and modified Nee evenness indices, and richness index based on rarefaction method were adopted to study the biodiversity of vespid wasps in spatial and temporal dimensions in northern Zanjan Province of Iran. In spatial dimension, Zanjan and Gilvan showed the highest and the lowest species diversity, evenness, and richness, respectively; while in tem-poral dimension, 16 July-6 August showed the highest species diversity and richness, and 18 May -27 May and 23 August -2 September showed the highest and the lowest species evenness,respectively. Significant differences in species abundance between localities of study area were observed by Kruskal-Wallis nonparametric test.