Colony Wide Behavioral Contexts of Stridulation in Imported Fire Ants (Solenopsis invicta Buren)

Red imported fire ants, Solenopsis invicta, possess stridulatory organs and stridulate in a variety of contexts. We used a stethoscope mounted microphone to study stridulation at the colony level in the context of emigration, disturbance, and excavation. In conjunction with preliminary observations of nest and foraging activities, our results suggest stridulation serves multiple functions in S. invicta. Stridulation was not significantly increased in colonies during responses to disturbance, and only marginally during colony emigration. Colonies involved in excavation, however, exhibited a significant increase in stridulatory activity. Four possible explanations for the function of stridulation in this context are discussed in relation to the stridulatory behavior of individuals, solitary wasps, and published literature on formicid stridulation.     

Pheromones released during inter- and intra-sex response of the scolytid beetle Dendroctonus brevicomis

Pheromones of Dendroctonus brevicomis released variously during inter- and intra-sex response (including stridulation by both sexes) were the known pheromones exo-brevicomin, endo-brevicomin, frontalin and verbenone, and substances identified as pinocarvone, trans-pinocarveol, and myrtenol. These substances are present in emergent beetles and thus attack of a host tree is not essential for their initial production.     

Sound production in scolytidae: 'rivalry' behaviour of male Dendroctonus beetles

Intrasex response of two males at the gallery of an attractive female included ‘rivalry’ stridulation that was distinct in certain acoustic properties from chirps evoked by the female attractant. With the southern pine beetle, Dendroctonus frontalis, comparison of chirps evoked by natural and synthetic chemostimulus confirmed that myrtenol is part of the female attractant, that verbenone is multifunctional according to its concentration, and that endo-brevicomin has a rivalry function as well as its anti-aggregative effect. Considerable acoustic specificity was apparent in tested chirps of three bark beetles.     

Stridulation and Courtship Behaviour of Four Endemic Pill-Millipedes, <Emphasis Type="Italic">Arthrosphaera</Emphasis> spp. (Sphaerotheriida: Arthrosphaeridae) of the Western Ghats of India

Mating behaviour of four species of pill-millipedes under genus Arthrosphaera Pocock (Arthrosphaera dalyi Pocock and Arthrosphaera disticta Pocock, Arthrosphaera fumosa Pocock and Arthrosphaera magna Attems) endemic to the Western Ghats of Southern India was analyzed in mesocosms. Stridulation is a classical communication signal in males as well as females for mate selection. Conglobation (or volvation) is a mechanism of defence to protect from disturbance or avoid predation. If male touches female or vice versa they conglobate. To avoid disparity among individuals of the same species, volvating pill-millipedes evolved stridulation behaviour for communication. The male broadcasts appropriate signal to female through stridulation to advertise its interest in mating. The females test the male’s fitness by conglobation and suitable male uncoils the partner through stridulation signals. Male with its pygidium successfully uncoils the female and attains suitable orientation for courtship. Male pairs with female ventro–ventro contact in opposite direction to deposit sperm into the vulva of female. The duration of mating varies from species to species and usually a lapse from 3 to 30 min. Vibration generated by stridulation is species-specific and its perception mechanism in pill-millipedes is yet to be clearly understood. Present study emphasized the structure of stridulatory organs, mechanism of stridulation and pattern of mating behaviour in four species of pill-millipedes.     

Acoustic defence in an insect: characteristics of defensive stridulation and differences between the sexes in the tettigoniid Poecilimon ornatus (Schmidt 1850)

Many insects exhibit secondary defence mechanisms upon contact with a predator, such as defensive sound production or regurgitation of gut contents. In the tettigoniid Poecilimon ornatus, both males and females are capable of sound production and of regurgitation. However, wing stridulatory structures for intraspecific acoustic communication evolved independently in males and females, and may result in different defence sounds. Here we investigate in P. ornatus whether secondary defence behaviours, in particular defence sounds, show sex-specific differences. The male defence sound differs significantly from the male calling song in that it has a longer syllable duration and a higher number of impulses per syllable. In females, the defence sound syllables are also significantly longer than the syllables of their response song to the male calling song. In addition, the acoustic disturbance stridulation differs notably between females and males as both sexes exhibit different temporal patterns of the defence sound. Furthermore, males use defence sounds more often than females. The higher proportion of male disturbance stridulation is consistent with a male-biased predation risk during calling and phonotactic behaviour. The temporal structures of the female and male defence sounds support a deimatic function of the startling sound in both females and males, rather than an adaptation for a particular temporal pattern. Independently of the clear differences in sound defence, no difference in regurgitation of gut content occurs between the sexes.     

Capture of large prey and feeding priority in the cooperative pseudoscorpion <Emphasis Type="Italic">Paratemnoides nidificator</Emphasis>

The social pseudoscorpion Paratemnoides nidificator is a common species in the Brazilian tropical savannah (Cerrado), where colonies are found under the bark of trees. In this environment, colonies hunt for large insects, subduing them by cooperative effort. Small insects are offered as food to nymphs, but large prey tends to be shared by colony members. We investigated the cooperative capture of large prey (Scarabaeidae beetles) by colonies of P. nidificator. During this process, some adults are involved in the immobilization and killing of prey. However, other adults stay as profiteers and do not offer help to subdue the prey. After prey immobilization, pseudoscorpions perform a hierarchical food share in which the attackers begin sucking the prey. These individuals favor the nymphs, offering them the prey and protection during feeding. Profiteer individuals are the last to feed on the carcass. In P. nidificator, obligatory parental care probably favors the evolution of behavioral strategies that prioritize the feeding of juveniles. This mechanism can provide better-quality food for the attackers but offers food to all colony members.     

宁夏盐池荒漠草原步甲物种多样性

采用巴氏罐诱法于2009年3月到10月对盐池四墩子3种不同类型荒漠草原的步甲物种组成、数量分布进行了系统调查,共获得步甲标本1318号,分属于9属15种,其中直角通缘步甲Pterostichus gebleri、蒙古伪葬步甲Pseudotaphoxnus mongolicus、径婪步甲Harpalus salinus和短翅伪葬步甲Pseudotaphoxnus brevipennis为优势种,个体数量分别占个体总数的33.08%、19.73%、15.94%和8.04%。多样性分析表明适度干扰荒漠草地的Shannon-Wiener多样性、丰富度和均匀度均高于低干扰和强干扰荒漠草地。群落相似性分析显示猪毛蒿和甘草混交带与围栏放牧带及柠条带有较高的相似性,蒙古冰草带和苜蓿与柠条混种带相似性较高。从时间动态上看,步甲群落的个体数量在8月份达到最高。4种优势种季节性变化分别是直角通缘步甲盛发期为8月,径婪步甲发生的高峰期为8、9月,短翅伪葬步甲在5月和8月,蒙古伪葬步甲7-10月个体数量均多;不同物种在不同类型荒漠草地出现的高峰期是不一致的。典范对应分析(CCA)分析表明土壤含水量是影响步甲分布的最重要环境因子,植物生物量和植被密度次之;土壤含水量与步甲的Shannon-Wiener多样性、均匀度显著负相关,与优势度呈显著正相关。     

Temperature-Dependent Clustering Behavior of Aethina Tumida Murray in Apis Mellifera L. Colonies

Temperate races of honey bees (Apis mellifera) are able to survive cold temperatures by forming thermoregulatory clusters. Small hive beetles (Aethina tumida), which inhabit honey bee colonies in their native range of sub-Saharan Africa and in their introduced ranges of the United States and Australia, are able to endure temperate climates by entering the bee cluster when cold temperatures persist. We conducted an experiment to address the temporal aspects of the cluster-entering behavior of small hive beetles. We did this by exposing beetle-infested observation bee hives to different ambient temperatures and counting the number of beetles remaining in confinement sites on the hive’s periphery at each temperature. The resulting regression analyses suggest that the beetles enter the cluster more rapidly than they exit it, a behavior possibly linked to a colony’s decision to form and dismantle a cluster.     

Sound production in Scolytidae: Female sonic stimulus of male pheromone release in two Dendroctonus beetles

The hypothesis that female sonic stimulus may evoke male pheromone release in a behavioural interaction analogous to the known male sonic stimulus of female pheromone release, was confirmed in Dendroctonus pseudotsugae, and also in D. brevicomis. In both species known male-produced substances collected from males stimulated by recorded female stridulation were identified by coupled gas chromatography/mass spectrometry. In a second test with D. pseudotsugae, male pheromone release during recorded female stridulation was evident in the change of male stridulation from the simple attractant chirp to the interrupted chirp, which is known to result from a medium concentration of 3,2-MCH. Also, the D. pseudotsugae male attractant chirp was synthesised with an electronic pulse generator and used to evoke pheromone release. It is concluded that the antiaggregative pheromone of this species is released by each sex at the sonic stimulus of the other sex.     

Changes in spatial and temporal distributions of Monochamus beetles along the fire severity in burned Pinus densiflora forests

Wildfire is an important disturbance factor in forest ecosystem and could affect the distribution of insects. Because Monochamus beetles are known vector insects of pine wood nematodes in Korea and burnt pine trees can be used as oviposition habitats for Monochamus beetles, we investigated changes in the spatial (among fire severity classes) and temporal (between years) distributions of M. alternatus and M. saltuarius. From late May 2017 to early October 2018, four multi-funnel traps with pheromone lure were installed in each fire severity class (unburned, light, light-moderate edge, moderate-severe edge, and severe). All traps were replaced fortnightly from May to October for two years. The spatial distribution of the two Monochamus beetles was significantly affected by fire severity. In particular, M. alternatus showed higher catches in the severely burned sites and responded positively to the fire. A similar number of M. saltuarius individuals were observed between 2017 and 2018, while more M. alternatus were caught in 2018 compared to 2017. Consequently, it was confirmed that the dead wood of P. densiflora caused by the wildfire had a great influence on the density of insects, especially M. alternatus.     

Mountain Pine Beetles Use Volatile Cues to Locate Host Limber Pine and Avoid Non-Host Great Basin Bristlecone Pine

The tree-killing mountain pine beetle (Dendroctonus ponderosae Hopkins) is an important disturbance agent of western North American forests and recent outbreaks have affected tens of millions of hectares of trees. Most western North American pines (Pinus spp.) are hosts and are successfully attacked by mountain pine beetles whereas a handful of pine species are not suitable hosts and are rarely attacked. How pioneering females locate host trees is not well understood, with prevailing theory involving random landings and/or visual cues. Here we show that female mountain pine beetles orient toward volatile organic compounds (VOCs) from host limber pine (Pinus flexilis James) and away from VOCs of non-host Great Basin bristlecone pine (Pinus longaeva Bailey) in a Y-tube olfactometer. When presented with VOCs of both trees, females overwhelmingly choose limber pine over Great Basin bristlecone pine. Analysis of VOCs collected from co-occurring limber and Great Basin bristlecone pine trees revealed only a few quantitative differences. Noticeable differences included the monoterpenes 3-carene and D-limonene which were produced in greater amounts by host limber pine. We found no evidence that 3-carene is important for beetles when selecting trees, it was not attractive alone and its addition to Great Basin bristlecone pine VOCs did not alter female selection. However, addition of D-limonene to Great Basin bristlecone pine VOCs disrupted the ability of beetles to distinguish between tree species. When presented alone, D-limonene did not affect behavior, suggesting that the response is mediated by multiple compounds. A better understanding of host selection by mountain pine beetles could improve strategies for managing this important forest insect. Moreover, elucidating how Great Basin bristlecone pine escapes attack by mountain pine beetles could provide insight into mechanisms underlying the incredible longevity of this tree species.     

Assessing tillage disturbance on assemblages of ground beetles (Coleoptera: Carabidae) by using a range of ecological indices

Many ecological studies have used diversity indices to assess the impact of environmental disturbance. In particular, ground beetles have been advocated as a good group for assessing disturbance. Most studies on various organisms have used only one or two indices. For our study of the impact of tillage disturbance on carabid beetles in farm fields in southern Ontario, Canada, we used seven different diversity indices (richness, Shannon–Wiener, Berger–Parker, Q-statistic, Margalef, and evenness). Few studies have used deviation from diversity abundance models as a measure of disturbance; however, we use three that are applicable to our data (geometric, log-normal and log-series). The indices and models were used to test the null hypothesis that there is no change in diversity with increasing tillage disturbance, and that there is no difference in diversity with different crops or years. We were not able to reject the null hypothesis that there is any diversity difference among farms. We also found that there was no single diversity index or model that was better than any other at detecting disturbance. These results are supplemented by a meta-analysis of 45 published data sets for the same taxon but in different habitats. The meta-analysis supports the conclusions from our field research that diversity indices and models are not useful for detecting the possible effect of disturbance on assemblages of carabid beetles.     

What determines the growth of individual castes in social trematodes?

Phenotypic diversification among colony members often leads to formation of physical castes which are morphologically specialised for particular tasks within the colony. The relative abundance of these castes and their body sizes represent two key aspects of the demography of a colony that may reflect the colony’s needs and conditions, and ultimately influence its survival and reproductive success. In a recently discovered social trematode, Philophthalmus sp., which exhibits a reproductive division of labour, the role of competition and colony composition in shaping reproductive success and behaviour of colony members has been documented. As body size variation within physical castes often influences colony efficiency, we investigated how the growth of reproductive and non-reproductive morphs of Philophthalmus sp. responds to competitive pressure, and to other attributes of colony demography such as colony size and composition. Our survey of a natural population and in vitro experiments demonstrate that the growth of reproductive colony members reflects the interaction between colony composition and the presence of a competitor, while the non-reproductive members simply grow larger in the presence of the intra-host competitor, Maritrema novaezealandensis. Furthermore, the close association between the volume and reproductive capacity of the reproductive members corroborates an adaptive value of colony member size in determining the fitness of the trematode colony as a whole. The present study is the first to demonstrate a fitness consequence, and identify the determinants, of the growth of colony members in social trematodes.     

crw1 - A Novel Maize Mutant Highly Susceptible to Foliar Damage by the Western Corn Rootworm Beetle

Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is the most destructive insect pest of corn (Zea mays L.) in the United States. The adult WCR beetles derive their nourishment from multiple sources including corn pollen and silks as well as the pollen of alternate hosts. Conversely, the corn foliage is largely neglected as a food source by WCR beetles, leading to a perception of a passive interaction between the two. We report here a novel recessive mutation of corn that was identified and named after its foliar susceptibility to corn rootworm beetles (crw1). The crw1 mutant under field conditions was exceptionally susceptible to foliar damage by WCR beetles in an age-specific manner. It exhibits pleiotropic defects on cell wall biochemistry, morphology of leaf epidermal cells and lower structural integrity via differential accumulation of cell wall bound phenolic acids. These findings indicate that crw1 is perturbed in a pathway that was not previously ascribed to WCR susceptibility, as well as implying the presence of an active mechanism(s) deterring WCR beetles from devouring corn foliage. The discovery and characterization of this mutant provides a unique opportunity for genetic analysis of interactions between maize and adult WCR beetles and identify new strategies to control the spread and invasion of this destructive pest.     

Colony-size effects on task organization in the harvester ant Pogonomyrmex californicus

Colony size is a fundamental attribute of insect societies that appears to play an important role in their organization of work. In the harvester ant Pogonomyrmex californicus, division of labor increases with colony size during colony ontogeny and among unmanipulated colonies of the same age. However, the mechanism(s) integrating individual task specialization and colony size is unknown. To test whether the scaling of division of labor is an emergent epiphenomenon, as predicted by self-organizational models of task performance, we manipulated colony size in P. californicus and quantified short-term behavioral responses of individuals and colonies. Variation in colony size failed to elicit a change in division of labor, suggesting that colony-size effects on task specialization are mediated by slower developmental processes and/or correlates of colony size that were missing from our experiment. In contrast, the proportional allocation of workers to tasks shifted with colony size, suggesting that task needs or priorities depend, in part, on colony size alone. Finally, although task allocation was flexible, colony members differed consistently in task performance and spatial tendency across colony size treatments. Sources of interindividual behavioral variability include worker age and genotype (matriline).     

Structure and evolution of stridulatory mechanisms in New Zealand wetas (Orthoptera : Stenopelmatidae)

Four types of stridulatory mechanisms were found in 35 species (7 genera) of New Zealand wetas (Orthoptera : Stenopelmatidae). These include: (1) tergo-femoral; (2) tergo-tergal; (3) mandbbuao-mandibular; and (4) pleuro-coxal. These fell into 12 groups, based upon shape, density and pattern of tergal and femoral pegs, number of terga bearing pegs and presence of mandibular tusks bearing stridulatory tubercles. The plesiomorphic condition, consisting of spinose peg patches on 3 or more abdominal tergites rubbed by bands of pegs on the femur, is found in Hemiandrus spp. Apomorphically-derived tergal files have arisen separately in 3 other genera. In Hemideina, (2 species groups) well-formed files are very similar among species. In Deinacrida, (4 species groups), the trend is toward file reduction into one or 2 massive tergal ridges, and embellished femoral pegs. In the tusked wetas (2 gen., 2 spp.), one species has a crude file of many broken ridges. Stridulatory structures on mandibular tusks of both New Zealand species are unique, although the tusks appear to have their origin in African stenopelmatids. The plesiomorphic condition appears to have been deployed originally for defense stridulation (inter-specific communication). Additional intea-specific stridulatory communication developed in Hemideina and Deinacrida, using the apomorphic file and peg mechanisms. Here, the stridulation is associated with defense, calling, mating and disturbance behaviors.     

Howardula dominicki n. sp. Infesting the Tobacco Flea Bettle in North Carolina

Howardula dominicki n. sp. is described from specimens collected from the tobacco flea beetle, Epitrix hirtipennis (Melsheimer), at Oxford, North Carolina , and is distinguished from other members of the genus . Parasitism by H. dominicki sterilized female flea beetles and often led to the death of larvae.     

Monitoring presence,abundance and survival probability of the stag beetle,Lucanus cervus,using visual and odour-based capture methods: implications for conservation

A capture-mark-recapture study on the threatened saproxylic beetle Lucanus cervus was carried out in a chestnut (Castanea sativa) woodland located in northern Italy, using visual encounter surveys (VES) as well as aerial flight interception traps and pitfall traps (PT), both of which were baited with different odour lures. In total, 111 males and 25 females were captured, and VES was by far the most efficient method, accounting for 93 % of first captures, and 95 % of all captures. Stag beetles were not significantly attracted to any tested odour, and many PT were damaged by wild boars (Sus scrofa). Flying males were the most frequent adults observed during the season. The use of a net is necessary to capture the stag beetles, in order to evaluate the population parameters and to assess the local status of threat for the species. Capture data revealed that body size (i.e. body weight and elytron length) influences the survival probability of stag beetles, showing a lower survival probability for larger males. Felt-tip pen marking on the ventral sclerites of head and pronotum is a reliable and long lasting method for marking beetles, as proved by the use of an independent marking procedure with a small drill. Assessing the presence and threat status of L. cervus across Europe is urgently needed, and with no efficient odour-based strategy available, collection of adult beetles, dead or alive, by VES is the most reliable way to monitor this emblematic species.     

Social encapsulation of the small hive beetle (<Emphasis Type="Italic">Aethina tumida</Emphasis> Murray) by European honeybees (<Emphasis Type="Italic">Apis mellifera</Emphasis> L.)

Summary European and African subspecies of honeybees (Apis mellifera L.) utilize social encapsulation to contain the small hive beetle (Aethina tumida Murray), a honeybee colony scavenger. Using social encapsulation, African honeybees successfully limit beetle reproduction that can devastate host colonies. In sharp contrast, European honeybees often fail to contain beetles, possibly because their social encapsulation skills may be less developed than those of African honeybees. In this study, we quantify beetle and European honeybee behaviours associated with social encapsulation, describe colony and time (morning and evening) differences in these behaviours (to identify possible circadian rhythms), and detail intra-colonial, encapsulated beetle distributions. The data help explain the susceptibility of European honeybees to depredation by small hive beetles. There were significant colony differences in a number of social encapsulation behaviours (the number of beetle prisons and beetles per prison, and the proportion of prison guard bees biting at encapsulated beetles) suggesting that successful encapsulation of beetles by European bees varies between colonies. We also found evidence for the existence of circadian rhythms in small hive beetles, as they were more active in the evening rather than morning. In response to increased beetle activity during the evening, there was an increase in the number of prison guard bees during evening. Additionally, the bees successfully kept most (~93%) beetles out of the combs at all times, suggesting that social encapsulation by European honeybees is sufficient to control small populations of beetles (as seen in this study) but may ultimately fail if beetle populations are high.Received 20 January 2003; revised 21 April 2003; accepted 29 April 2003.     

Horizontal Transmission of Bursaphelenchus xylophilus between Sexes of Monochamus alternatus

Four experiments were conducted using nematode-infested and nematode-free adults of the cerambycid beetle, Monochamus alternatus, to determine horizontal transmission pathways of Bursaphelenchus xylophilus. When nematode-infested beetles of one sex and nematode-free beetles of the opposite sex were paired in containers for 48 or 72 hours, the number of nematodes carried by nematode-free beetles tended to increase with increased number of nematodes carried by nematode-infested beetles. The nematodes acquired by "nematode-free" beetles could be transmitted to pine. A female beetle that received 13 nematodes from a male transmitted one nematode to a Pinus densiflora bolt via an oviposition wound. When the nematode-infested and nematode-free beetles were observed continuously, it was observed that the number of nematodes carried by nematode-free beetles at the end of the first sexual mounting increased as the number of nematodes carried by nematode-infested beetles just before mounting increased. The number of nematodes transferred to nematode-free beetles was positively related to duration time of mounting. There was no difference in transmission efficacy between male-to-female transmission and female-to-male transmission. The horizontal transmission pathways are discussed relative to the persistence of B. xylophilus in resistant pine forests and the control of pine wilt disease.