Long‐term spatial memory in Vespula germanica social wasps: the influence of past experience on foraging behavior

Social insects exhibit complex learning and memory mechanisms while foraging. Vespula germanica (Fab.) (Hymenoptera: Vespidae) is an invasive social wasp that frequently forages on undepleted food sources, making several flights between the resource and the nest. Previous studies have shown that during this relocating behavior, wasps learn to associate food with a certain site, and can recall this association 1 h later. In this work, we evaluated whether this wasp species is capable of retrieving an established association after 24 h. For this purpose, we trained free flying individuals to collect proteinaceous food from an experimental plate (feeder) located in an experimental array. A total of 150 individuals were allowed 2, 4, or 8 visits. After the training phase, the array was removed and set up again 24 h later, but this time a second baited plate was placed opposite to the first. After 24 h we recorded the rate of wasps that returned to the experimental area and those which collected food from the previously learned feeding station or the nonlearned one. During the testing phase, we observed that a low rate of wasps trained with 2 collecting visits returned to the experimental area (22%), whereas the rate of returning wasps trained with 4 or 8 collecting visits was higher (51% and 41%, respectively). Moreover, wasps trained with 8 feeding visits collected food from the previously learned feeding station at a higher rate than those that did from the nonlearned one. In contrast, wasps trained 2 or 4 times chose both feeding stations at a similar rate. Thus, significantly more wasps returned to the previously learned feeding station after 8 repeated foraging flights but not after only 2 or 4 visits. This is the first report that demonstrates the existence of long‐term spatial memory in V. germanica wasps.     

Evidence of associative blocking during foraging in the social wasp Vespula germanica

While foraging, Vespula germanica usually return to abundant food sites. During this relocation behavior, these wasps learn to identify contextual cues associated with food position. We analyzed associative blocking in this species, that is, how an association with a conditioned stimulus (CS1) blocks subsequent learning when a novel stimulus (CS2) is added on a second foraging visit. Three groups of wasps (A, B, and C; total 74 individual wasps) were observed while collecting meat during one or two consecutive visits. In group A, an environmental cue (CS1) was paired with food placed at a specific site, and on the second visit, a second cue (CS2) was added while food remained in the same position. In a subsequent testing phase, CS1 was removed and the food source displaced nearby. We then recorded the number of hovers performed over the empty dish (previously baited). Group A wasps appeared to ignore the addition of CS2 on their second visit because they performed fewer hovers over the learned site. For group A, the duration of the decision-making process to finally fly toward the baited dish was shorter than when CS1 and CS2 were presented together on their first visit (group B). This is the first study to demonstrate the occurrence of associative blocking in vespids, confirming that a prior foraging experience influences subsequent food relocation in V. germanica. Our findings reveal that first learning episodes block further associations with novel contextual cues, contributing to understanding of complex cognitive processes involved in V. germanica´s foraging behavior.     

The influence of habitat use and foraging on the replacement of one introduced wasp species by another in New Zealand

Abstract.

• 1 New Zealand was colonized by the German wasp, Vespula germanica (F.), in the 1940s and it subsequently became established throughout the country. The common wasp, V.vulgaris (L), colonized in the late 1970s and is still spreading.
• 2 The common wasp has replaced the German wasp in some habitats in New Zealand. Samples from a nationwide postal survey indicate that the common wasp is now the more abundant species in honeydew beech forests (Nothofagus spp.), and to a lesser extent in other native forests. The German wasp is still the more abundant wasp in rural areas (excluding forest). The two species are at present co-dominant in urban areas, although this may be a transient phase.
• 3 In honeydew beech forest the two species show different foraging patterns that provide the potential for local coexistence. Although both species are generalist feeders, the German wasp is more commonly found foraging for protein amongst the forest litter, whereas the common wasp forages more on shrubs and tree saplings. Despite this difference, the common wasp can still replace the German wasp in honeydew beech forest within a few years of invasion.
• 4 In honeydew beech forests in which the German wasp is the more abundant species it dominates honeydew trunks (sugar resource), whereas the common wasp dominates honeydew trunks in areas where it is the more abundant species. The change from German to common wasp domination of honeydew trunks is more rapid than the change in dominance in other microhabitats. Aggressive interactions may be taking place on this high quality, potentially defensible sugar resource.

     

The importance of location and visual cues during foraging in the German wasp (Vespula germanica F.) (Hymenoptera: Vespidae)

Abstract

The way in which foraging wasps use cues for prey location and choice appears to depend on both the context and on the type of prey. Vespula germanica is an opportunistic, generalist prey forager, and individual wasp foragers often return to hunt at sites of previous hunting success. In this paper, we studied which cues are used by this wasp when relocating a food source. Particularly we analysed the response to a displaced visual cue versus a foraging location at which either honey or cat food had been previously presented. We conclude that location is used over a displaced visual cue for directing wasp hovering, although the landing response is directed differently according to bait type. When wasps are exploiting cat food, location also elicits landing, but if they are exploiting honey, a displaced visual cue elicits landing more frequently than location.     

Contrasting foraging related behaviours in two sympatric wasps (Vespula maculifrons and V. germanica)

ABSTRACT.

• 1 Using pinned freshly killed wasps (yellowjackets) to simulate feeding animals, it was found that V. germanica was socially facilitated, and concentrated its foraging activity on those feeders with the most pinned wasps (twenty). V. maculifrons foragers responded inversely, preferentially foraging at feeders with few or no pinned wasps.
• 2 Using hand-painted drawing pins (thumb tacks) as wasp models, similar results were found, indicating that visual, rather than olfactory, cues were responsible for the observed distribution.
• 3 Vespula maculifrons and V. germanica exhibit aggression while foraging at honey-baited feeders. Both species attack conspecifics at frequencies lower than would be expected under random encounter.

     

社群学习对植食性鸟类和哺乳动物觅食行为的作用

社群学习是动物的一种可塑性行为表现型式。综述了社群学习对植食性鸟类和哺乳动物觅食行为的作用,并述评了其学习机制。社群同伴对动物个体觅食地点、时间和取食方式均有影响,母体摄食的食物信息可通过胎盘和乳汁显著影响幼体的食物选择。动物通过观察学习、嗅闻学习以及味觉厌恶学习,不仅能更快找到食物资源,提高觅食效率,而且能有效降低中毒与被捕食的风险,从而提高其适合度。     

Influence of caterpillar-feeding damage on the foraging behavior of the paper waspMischocyttarus flavitarsis (Hymenoptera: Vespidae)

Experiments were performed to determine the effect of caterpillar feeding damage on wasp foraging behavior and to determine the relative importance of visual and olfactory plant cues for foraging wasps. In an experiment using caterpillar-damaged leaves, wasps took significantly more larvae from the previously damaged plants compared to the controls in the experiments with tobacco plants, but wasps did not distinguish between damaged and control plants in the experiments with tomato plants. Another experiment indicated that wasps use a combination of visual and olfactory cues of plant damage in their search for prey rather than just visual or olfactory cues alone. Furthermore, these results suggest that leaf shape may affect wasp detection of caterpillar feeding damage and thus detection of prey.     

The spread of the social wasp,Vespula germanica,in Australia

Abstract

Between 1977 and 1989 the social wasp Vespula germanicacolonised mainland Australia and became established in New South Wales, Victoria, and South Australia. Accidental transport between towns is the main mechanism of spread. In many towns wasp nests have not been detected until they became widespread; therefore, eradication is difficult Successful eradication has, however, been achieved in many other towns.

Nesting places vary considerably among localities but relatively little among years at anyone locality. Peak wasp abundance occurs between January and April. Control of V. germanica nests costs Australia an estimated $600,000 (Aust. $) annually.     

寄生经历对川硬皮肿腿蜂寄主搜索行为的影响

研究寄生经历对川硬皮肿腿蜂SclerodmasichuanensisXiao寄主搜索行为的影响的结果表明,在指形管内,有寄生经历的川硬皮肿腿蜂产卵准备时间比无寄生经历蜂短,寄主搜索控制时间更少,寄主搜索控制成功率更高。1～3次经历蜂随着经历次数的增加,产卵准备时间逐渐缩短。无经历、1次、2次、3次经历蜂的产卵准备期分别为:6.3,5.3,4.9,4.6d。但3次经历后,准备时间的变化即不显著。无经历蜂与1次经历蜂、5次经历蜂的搜索控制寄主时间分别为:820,240,30min,对寄主的搜索控制成功率分别为72.97%,100%,100%。寄生经历蜂接蜂3d时卵子发育速率更快,寄生经历蜂与无寄生经历蜂在替代寄主上的产卵量差异不显著。     

蜜蜂花粉采集行为的调控机制

蜜蜂Apisspp.是一种社会性昆虫。社会性昆虫在对它们群体自身数量和巢穴环境的调节方面表现出明显的稳态特点,Emerson将这种稳态调节称为社会性稳态。蜂群中花粉的储存量就具有稳态的特点。蜂群的花粉采集行为是由蜂群对花粉的需要决定的。关于蜜蜂花粉采集行为的调控机制,目前的研究主要集中于是哪些信息以及蜂群是如何识别这些信息从而调控其采粉行为,主要形成了直接识别和间接识别2种假说。对这2种假说进行综述。     

Distribution of social wasps (Hymenoptera: Vespidae) in New Zealand in 1987

Abstract

More than 50 000 social wasps (Hymenoptera: Vespidae) were collected between March and August 1987 from throughout New Zealand. The most widespread species is the German wasp (Vespula germanica). The common wasp (V. vulgaris) has colonised about half the country and appears to be still spreading. It tends to appear in urban areas first, presumably because it is transported there with people and/or their belongings. The Asian paper wasp (Polistes chinensis) and Australian paper wasp (P. humilis), are confined to the northern half of the North Island, but the former species is spreading south.     

Structure-guided foraging in long-tailed macaques

The aim of this study was to identify some of the cues that macaques follow when they search for new food sites. A social group of 37 long-tailed macaques was confined to a holding cage while an experimenter concealed food in an outdoor enclosure according to one of the following rules: (1) along the edge of a visible environmental border, (2) within structures of the same general type, or (3) along an ecologically irrelevant, invisible straight line. To provide the animals with a cue for detecting the rule, three piles of visible food were also presented according to the rule. Each of the 60 trials involved a different location in the 880 m² enclosure. The animals showed clear evidence of utilizing the first two rules from the outset of testing and the third rule about five trials. The animals found concealed food along environmental borders and within matching objects more quickly than along invisible lines. They also showed a rapid improvement in food finding on the invisible line. The results suggest that long-tailed macaques extend their search for food to a given class of environmental structure rather than exclusively by pure spatial gradients. © 1996 Wiley-Liss, Inc.     

Amygdaloid and non-amygdaloid fear both influence avoidance of risky foraging in hungry rats

Considerable evidence seems to show that emotional and reflex reactions to feared situations are mediated by the amygdala. It might therefore seem plausible to expect that amygdala-coded fear should also influence decisions when animals make choices about instrumental actions. However, there is not good evidence of this. In particular, it appears, though the literature is conflicted, that once learning is complete, the amygdala may often not be involved in instrumental avoidance behaviours. It is therefore of interest that we have found in rats living for extended periods in a semi-naturalistic ‘closed economy’, where they were given random shocks in regions that had to be entered to obtain food, choices about feeding behaviour were in fact influenced by amygdala-coded fear, in spite of the null effect of amygdalar lesions on fear of dangerous location per se. We suggest that avoidance of highly motivated voluntary behaviour does depend in part on fear signals originating in the amygdala. Such signalling may be one role of well-known projections from amygdala to cortico-striate circuitry.     

A variable-response model for parasitoid foraging behavior

An important factor inducing variability in foraging behavior in parasitic wasps is experience gained by the insect. Together with the insect's genetic constitution and physiological state, experience ultimately defines the behavioral repertoire under specified environmental circumstances. We present a conceptual variable-response model based on several major observations of a foraging parasitoid's responses to stimuli involved in the hostfinding process. These major observations are that (1) different stimuli evoke different responses or levels of response, (2) strong responses are less variable than weak ones, (3) learning can change response levels, (4) learning increases originally low responses more than originally high responses, and (5) hostderived stimuli serve as rewards in associative learning of other stimuli. The model specifies how the intrinsic variability of a response will depend on the magnitude of the response and predicts when and how learning will modify the insect's behavior. Additional hypotheses related to the model concern how experience with a stimulus modifies behavioral responses to other stimuli, how animals respond in multistimulus situations, which stimuli act to reinforce behavioral responses to other stimuli in the learning process, and finally, how generalist and specialist species differ in their behavioral plasticity. We postulate that insight into behavioral variability in the foraging behavior of natural enemies may be a help, if not a prerequisite, for the efficient application of parasitoids in pest management.     

The effects of foraging demand on social interactions in a laboratory group of Bonnet Macaques

The relationship between foraging demand and social behavior was experimentally studied in a laboratory group of bonnet macaques. Fourteen adult animals were housed in a large outdoor enclosure containing three shallow gravelfilled circular containers that served as the foraging sites. During the experimental foraging sessions raisins were placed in the containers and the social and foraging behaviors of the group were observed for 50 min following the distribution of raisins. Three types of foraging conditions were inter-spersed with one another on different test days: (1) surface load— raisins placed on top of the gravel; (2) buried load— raisins hidden underneath the gravel; and (3) sham load— no raisins placed at the foraging sites. Three basic foraging patterns, defined along a temporal dimension, were seen. One group of animals completed 50% of their total foraging by the end of the first 15 min. A second group foraged more steadily through the session. A third group foraged late, completing 50% of their foraging during the last half of the session. The foraging patterns were similar in the buried and surface condition, although the patterns were more compressed during the surface condition. More aggression and more avoidance of other animals occurred in the buried condition than in the surface condition. Very little foraging occurred during the sham condition. There was no clear relationship between the patterns of interaction during foraging and nonforaging observation sessions. The results suggest the value of manipulative laboratory studies in examining the relationship between ecological variables and social behavior in nonhuman primates.     

Size effects on the hygrothermal balance and foraging patterns of a sphecid wasp, Cerceris arenaria

Abstract. 1. Cerceris arenaria (L.) females nest in sandy burrows, foraging for prey weevils to stock cells in which eggs are laid. Nests are easily distinguished and observed, and tunnel diameter correlates well with the occupying females' size (range 68–128 mg).
2. Foraging depends on ambient temperature and occurs only during periods of insolation. Large females can forage earlier in the day, and usually make a greater number of successful trips per day, than smaller ones.
3. Size differences of females affect heat exchange and resultant temperature excesses (T_ex). At the highest ambient temperatures T_ex for the largest wasps can exceed physiological tolerances, thus reducing foraging activity relative to the smaller females.
4. On very hot days wasps forage more frequently for nectar, probably to reduce their water deficits. Larval water balance is controlled less directly, by the architecture of burrows and the nature of cell walls and contents.
5. Temperature effects on foraging and nesting bring about a roughly two-fold increase in success as cell provisioners (and hence egg-layers) of larger over smaller females. Possible countering effects of very hot weather and of parasitism, either of which might favour small females in some conditions, are discussed.     

Study on foraging mechanism of leeches with different feeding habits based on chemoreception and foraging behavior

The leeches Whitmania pigra and Hirudo nipponia live in similar environments but have different feeding habits. At present, there are few studies of the foraging mechanism of leeches with different feeding habits. In this study, we first used maze tests to show that these two species of leeches could locate and distinguish their prey through chemosensory activity without mechanical stimulation. However, the two leech species have different foraging behaviors: Individuals of W. pigra move slowly and repeatedly adjust direction through probing and crawling to detect the location of prey (snails), whereas individuals of H. nipponia move quickly, and after determining the location of food (porcine blood), they quickly swim or crawl to the vicinity of their prey. Scanning electron microscopy (SEM) revealed that there are two types of sensory cilia and pore structures related to mucus secretion in the heads of both leeches. There are two differently sized types of chemoreceptors on the dorsal lip in W. pigra, which may have different functions during foraging, whereas in H. nipponia there is only one type of chemoreceptor, which is small. We detected the chemical components in the natural food of these two leech species by UHPLC–MS. There were 934 metabolites in the body fluid of snails and 751 metabolites in porcine serum; five metabolites unique to the body fluid of snails and to porcine serum were screened as candidate feeding attractants. Of these metabolites, betaine and arginine effectively attracted individuals of W. pigra and H. nipponia, respectively. In summary, leeches with different feeding habits use chemoreceptors to sense external chemical signals when foraging, and there are significant differences between species in foraging behavior, chemoreceptors, and attractants.