Subterranean termites (Isoptera: Rhinotermitidae): Exploitation of equivalent food resources with different forms of placement

Abstract Coptotermes gestroi and Heterotermes tenuis have been described as important urban pests in Brazil. The establishment of control technologies using baits that consider the social behavior of termites requires a better knowledge of their foraging behavior. Thus, this study analyzed the feeding behavior of these species with three different forms of food placement: food on the surface of a substrate and food either partially or completely buried in the substrate. Experimental arenas were composed of a central chamber connected to three food chambers. Each central chamber contained 550 foragers of C. gestroi or 517 foragers of H. tenuis. Blocks of Pinus elliottii were placed in the different food chambers. After 28 days, the consumption of each wood block and the percentage of foraging individuals recruited for food chambers were verified in relation to the total survival rate obtained for each one of the 20 replicates. Results showed that completely buried food was most consumed for H. tenuis and presented a higher recruitment rate of workers and soldiers for both species. Although the consumption had non‐significant differences for C. gestroi, these termites exhibited a tendency to prefer completely buried food. In these conditions, it can be concluded that the forms of food placement used in the present research influenced the recruitment of individuals for both species. Data also suggests that when the foraging subterranean termites find food resources in the tunneling substrate, they tend to concentrate their efforts on it, a behavior regime that reduces exposure to external environment.     

Partner effects on food consumption in brown capuchin monkeys

It has been claimed that capuchin monkeys (Cebus apella) show inequity aversion in relation to food rewards for a simple exchange task. However, other factors may affect the willingness of a monkey to consume foods of high or low value in the presence of a conspecific. In this study, pairs of monkeys were presented with unequally valued foods, but without any task-performance: they simply received the food under four experimental conditions. By looking at the rate of collection and consumption of low-valued cucumber slices we expected to see variation dependent on whether the partner either had 1) cucumber (equity), 2) grape (inequity), 3) inaccessible cucumber or 4) inaccessible grape. Testing 12 adult capuchin monkeys, our findings differed from those of other authors in that the monkeys failed to show negative reactions to inequity, but rather responded with scramble competition (i.e., fast food collection) in the presence of a conspecific without access to food. They also showed facilitated consumption in the presence of a conspecific consuming high-valued food. Possibly, (in)equity plays a different role if food serves as a reward for a task rather than if it is simply made available for consumption.     

Hazel grouse (Bonasa bonasia) pairs during the nonbreeding season: mutual benefits of a cooperative alliance

During the nonbreeding season (autumn and winter), hazel grouse(Bonasa bonasia) males and females associate as loosely boundpairs, not as strongly bound pairs as previously thought. Thesepairs could be considered cooperative alliances, with each membergaining both direct and indirect benefits. The most importantdirect benefit appeared to be mutual vigilance against predators.This benefit was found at two levels: at the level of arborealfeeding sites, two birds could forage faster and farther fromcover than single birds, and at the territory scale, the pairwas together more in dangerous habitats. By foraging fartherfrom cover, two birds could use about 23% more of the preferredfood trees and 9%–10% more of the food available withina territory than a single bird, partially mitigating the costof having two birds feeding on limited winter food in the samespace. Defending a common territory appeared to be a less importantdirect benefit of the alliance because the members of a pairdid not defend the same territory and often associated withneighboring birds of the opposite sex. A future benefit of thealliance was having breeding partners in the spring; this wasmost beneficial for males, as the sex ratio was male biased.Members of the pair were often apart. At arboreal feeding sites,this separation was perhaps because the most preferred trees,black alders (Alnns glutinosa) with the most staminate catkins,were located in areas with the most cover, where one bird maybe safer from predators than two. Members of pairs in more securehabitats were more often with extrapair birds of the oppositesex. This suggested a trade-off; birds in safe habitats mayhave visited potential breeding partners, but birds in dangeroushabitats may have had to remain together, foregoing this option,to increase their survival probability. This social organizationappeared to be an adaptation to surviving in a heterogeneoushabitat, with some of the winter food located in dense coverand some located in more open and dangerous situations.     

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.     

拟小食螨瓢虫成虫对朱砂叶螨的觅食行为

为明确拟小食螨瓢虫的觅食特性,揭示其觅食行为机制,本研究针对拟小食螨瓢虫成虫对朱砂叶螨不同虫态的取食选择、日取食节律以及觅食行为活动特点等进行了观察和阐述。结果表明,拟小食螨瓢虫成虫对朱砂叶螨卵、幼螨、若螨和成螨的取食嗜好性有显著差异,取食量分别为23.2、15.8、10.5和8.0头;瓢虫对成螨的平均日取食量为14.7头,其中在白天其觅食行为较频繁,9∶00-12∶00为捕食高峰期,此时段的平均取食量为4.0头成螨,夜间基本不取食;其觅食行为过程主要分为7个部分:搜索、捕捉、嚼食、梳理、展翅、排泄和静止。     

Fights at the Dinner Table: Agonistic Behavior in Pachydiplax longipennis (Odonata: Libellulidae) at Feeding Sites

Aggressive behavior of Pachydiplax longipennis during foraging was quantified by observing focal individuals on arrays of artificial perches. Pachydiplax apparently aggressively defend, for up to several hours at a time, one or a few feeding perches. Seventeen percent of all behaviors included agonistic actions, e.g., chasing or physical contact. The frequency of interactions was correlated positively with ambient temperature, solar radiation, prey density and density of other dragonflies. Both sexes initiated and responded to intra- and interspecific aggression; intraspecific interactions were more intense, however. Males had significantly higher interaction rates and fighting success than females, and intraspecific male–male contests were particularly intense. When prey were visibly localized, contest winners commonly gained perches closer to the prey swarm, and aggressive behavior was apparently correlated with feeding opportunity. Despite the frequency of aggression, these dragonflies allocated only about 19 s, on average, to agonistic behavior during 30-min observation periods. This and other costs appear small compared to foraging benefits of occupying a favorable perch, although at a very high interaction intensity high energy costs and lower intake reduce the net energy gain.     

Behavioral interference and facilitation in the foraging cycle shape the functional response

Individual forager behaviors should affect per capita intakerates and thereby population and consumer-resource properties.We consider and incorporate conspecific facilitation and interferenceduring the separate foraging-cycle stages in a functional responsemodel that links individual behavioral interactions with consumer-resourceprocesses. Our analyses suggest that failing to properly considerand include all effects of behavioral interactions on foraging-cyclestage performances may either over- or underestimate effectsof interactions on the shape of both functional responses andpredator zero-growth isoclines. Incorporation of prey- and predator-dependentinteractions among foragers in the model produces predator isoclineswith potentials for highly complex consumer-resource dynamics.Facilitation and interference during the foraging cycle aretherefore suggested as potent behavioral mechanisms to causepatterns of community dynamics. We emphasize that correct estimationsof interaction-mediated foraging-cycle efficiencies should beconsidered in empirical and theoretical attempts to furtherour understanding of the mechanistic link between social behaviorsand higher order processes.     

昆虫个体大小对其种群生物学的影响

个体大小是昆虫种群最直观的表型之一。很多研究发现,个体大小可对昆虫的许多生物学特性产生影响,由此影响昆虫种群的发展以及所在群落的结构和功能。根据最近20多年的相关文献,综述了个体大小对种群以下几方面的影响:成虫求偶、交配、生殖力及后代适合度,飞行及与飞行相关的其他行为如觅食、空中求偶和交配,摄食能力和食料种类,竞争和防御能力,抗逆性,以及社会性昆虫的劳动分工等。通常情况下,与同种内较小个体相比,较大的昆虫在生殖、飞行、抗逆性等方面往往具有优势,有助于种群适合度的提高。最后提出了几点可供此领域研究参考的建议和应用启示。     

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。     

Prey size, prey nutrition, and food handling by shrews of different body sizes

We tested some predictions relating metabolic constraints offoraging behavior and prey selection by comparing food handlingand utilization in four sympatric shrew species: Sorex minutus(mean body mass = 3.0 g), S. araneus (8.0 g), Neomys anomalus(10.0 g), and N. fodiens (14.4 g). Live fly larvae, mealwormlarvae, and aquatic arthropods were offered to shrews as smallprey (body mass <0.1 g). Live earthworms, snails, and smallfish were offered as large prey (>0.3 g). The larvae werethe high-nutrition food (>8 kJ/g), and the other prey werethe low-nutrition food (<4 kJ/g). The smallest shrew, S.minutus, utilized (ate + hoarded) <30% of offered food,and the other species utilized >48% of food. The largerthe shrew, the more prey it ate per capita. However, highlyenergetic insect larvae composed 75% of food utilized by S.minutus and only >40% of the food utilized by the other species. Thus, inverse relationships appeared between shrewbody mass and mass-specific food mass utilization and betweenshrew body mass and mass-specific food energy utilization:the largest shrew, N. fodiens, utilized the least food massand the least energy quantity per 1 g of its body mass. Also,the proportion of food hoarded by shrews decreased with increase in size of shrew. With the exception of S. araneus, the sizeof prey hoarded by the shrews was significantly larger thanthe size of prey eaten. Tiny S. minutus hoarded and ate smallerprey items than the other shrews, and large N. fodiens hoardedlarger prey than the other shrews.