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In the eastern United States, there are nine species of subterranean termites in three genera: Reticulitermes (six species), Coptotermes (two species), and Prorhinotermes (one species). These species serve as important ecological players by decomposing cellulose material, and some are important structural pests. Many of these species are difficult to discriminate morphologically and require examining the reproductive or soldier castes, which can be difficult to collect. While some genetic tools have been developed for species identification, they are often expensive and time-consuming. To help facilitate identification, we developed a more cost-effective and rapid genetic method to identify Reticulitermes species by screening 10 PCR primers that amplified inter-simple sequence repeats (ISSRs) in other termite species. From these, one primer was amplified in all five focal Reticulitermes species and contained conserved, species-specific fragments. We further screened this identification method on samples of each species covering a diversity of mitochondrial DNA haplotypes and localities. This identification method utilizing ISSRs can be used to quickly identify five species of Reticulitermes subterranean termites in the eastern United States in a matter of hours, providing a useful technique for pest management as well as future ecological research.

Most honey bee (Apis mellifera Linnaeus, 1758) (Hymenoptera: Apidae) colonies in the United States have been exposed to the beekeeper-applied miticides amitraz, coumaphos, and tau-fluvalinate. Colonies are also often exposed to agrochemicals, which bees encounter on foraging trips. These and other lipophilic pesticides bind to the beeswax matrix of comb, exposing developing bees. We explored whether queen-rearing beeswax containing pesticides affects the reproductive health of mated queens. We predicted that queens reared in pesticide-free beeswax would have higher mating frequencies and sperm viability of stored sperm compared with queens reared in wax containing pesticides. Mating frequency and sperm viability are two traditional measurements associated with queen reproductive health. To test these hypotheses, we reared queens in beeswax-coated cups that were pesticide free or contained field-relevant concentrations of 1) amitraz, 2) a combination of tau-fluvalinate and coumaphos, or 3) a combination of the agrochemicals chlorothalonil and chlorpyrifos. We then collected queens once they mated to determine sperm viability, using a dual fluorescent cell counter, and mating frequency, genotyping immature worker offspring at eight polymorphic microsatellite loci. Sperm viability did not differ between control queens and those reared in pesticide-laden wax. However, queens exposed to amitraz during development exhibited higher mating frequency than queens reared in pesticide-free beeswax or beeswax containing the other pesticide combinations. Our results suggest that miticide exposure during development affects queen mating frequency but not sperm viability, at least in newly mated queens. This finding, which has practical implications for commercial queen rearing and overall colony health, calls for further study.

In some species of social insects the increased genetic diversity from having multiple breeders in a colony has been shown to improve pathogen resistance. Termite species typically found colonies from single mated pairs and therefore may lack the flexibility to buffer pathogen pressure with increased genetic diversity by varying the initial number of reproductives. However, they can later increase group diversity through colony merging, resulting in a genetically diverse, yet cohesive, workforce. In this study, we investigate whether the increased group diversity from colony fusion benefits social immunity in the subterranean termite Reticulitermes flavipes. We confirm previous findings that colonies of R. flavipes will readily merge and we show that workers will equally groom nestmates and non-nestmates after merging. Despite this, the survival of these merged colonies was not improved after exposure to a fungal pathogen, but instead leveled to that of the more susceptible or the more resistant colony. Our study brings little support to the hypothesis that colony fusion may improve immunity through an increase of genetic diversity in R. flavipes. Instead, we find that following exposure to a lethal pathogen, one colony is heavily influential to the entire group’s survival after merging.

The production of royal pheromones by reproductives (queens and kings) enables social insect colonies to allocate individuals into reproductive and non-reproductive roles. In many termite species, nestmates can develop into neotenics when the primary king or queen dies, which then inhibit the production of additional reproductives. This suggests that primary reproductives and neotenics produce royal pheromones. The cuticular hydrocarbon heneicosane was identified as a royal pheromone in Reticulitermes flavipes neotenics. Here, we investigated the presence of this and other cuticular hydrocarbons in primary reproductives and neotenics of this species, and the ontogeny of their production in primary reproductives. Our results revealed that heneicosane was produced by most neotenics, raising the question of whether reproductive status may trigger its production. Neotenics produced six additional cuticular hydrocarbons absent from workers and nymphs. Remarkably, heneicosane and four of these compounds were absent in primary reproductives, and the other two compounds were present in lower quantities. Neotenics therefore have a distinct ‘royal’ blend from primary reproductives, and potentially over-signal their reproductive status. Our results suggest that primary reproductives and neotenics may face different social pressures. Future studies of these pressures should provide a more complete understanding of the mechanisms underlying social regulation in termites.

Evaluating the factors that promote invasive ant abundance is critical to assess their ecological impact and inform their management. Many invasive ant species show reduced nestmate recognition and an absence of boundaries between unrelated nests, which allow populations to achieve greater densities due to reduced intraspecific competition. We examined nestmate discrimination and colony boundaries in introduced populations of the red imported fire ant (Solenopsis invicta; hereafter, fire ant). Fire ants occur in two social forms: monogyne (colonies with a single egg-laying queen) and polygyne (colonies with multiple egg-laying queens). In contrast with monogyne nests, polygyne nests are thought to be interconnected due to the reduced antagonism between non-nestmate polygyne workers, perhaps because polygyne workers habituate the colony to an odor unique to Gp-9-carrying adults. However, colony boundaries and nestmate discrimination are poorly documented, particularly for worker-brood interactions. To delimit boundaries between field colonies, we correlated the exchange of a N-glycine tracer dissolved in a sucrose solution with social form. We also evaluated nestmate discrimination between polygyne workers and larvae in the laboratory. Counter to our expectations, polygyne colonies behaved identically to monogyne colonies, suggesting both social forms maintain strict colony boundaries. Polygyne workers also preferentially fed larval nestmates and may have selectively cannibalized non-nestmates. The levels of relatedness among workers in polygyne colonies was higher than those previously reported in North America (mean ±SE: 0.269 ± 0.037). Our study highlights the importance of combining genetic analyses with direct quantification of resource exchange to better understand the factors influencing ant invasions.

Made available in DSpace on 2020-12-12T02:29:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Termite colonies are usually headed by primary reproductives, which establish nests during the swarming season. However, secondary reproductives may develop in some species and become supplementary or replacement breeders, extending colony lifespan. Here we investigate the developmental origin, fecundity and genetic characterization of ergatoid reproductives in the Neotropical termite Nasutitermes aquilinus (Holmgren), using morphometrical and histological techniques, five microsatellite loci and the COI mitochondrial DNA. Twelve measurements performed on 208 apterous individuals of N. aquilinus revealed 10 groups, including ergatoid females, which developed from major workers through two successive molts, and were characterized by the presence of imaginal features such as eyes and wing buds. The differentiation of these features was correlated to physogastric development in these ergatoids. Histology revealed oocytes in all maturation stages in worker-derived reproductives of N. aquilinus, presence of nonflagellate spermatozoa inside the spermatheca, and royal fat body. Thus, ergatoid reproductives were reproductively functional. According to the genotypes of 221 individuals from 11 nests, and mitochondrial haplotypes of 43 ergatoids, 73% of the colonies were simple families, whereas 27% were extended families. Despite the occurrence of related reproductives, low inbreeding rates were detected within and among colonies. Such values could be explained given that sib mating itself cannot result in a higher inbreeding rate but depend on several factors discussed in detail. This is the first study to investigate the genetic structure of termite colonies influenced by the development of ergatoids, and further investigations are encouraged to understand the influence of these reproductives on colony lifespan. Laboratório de Cupins Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista—UNESP Centro de Ciências Naturais e Humanas Universidade Federal do ABC Department of Entomology Texas A&M University Departamento de Ciências Biológicas Universidade Federal de São Paulo—UNIFESP Instituto de Ciências Agrárias Universidade Federal de Uberlândia UFU Centro de Estudos em Recursos Naturais Universidade Estadual de Mato Grosso do Sul Laboratório de Cupins Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista—UNESP

In recent decades, the world has witnessed a remarkable resurgence of bedbugs (Hemiptera: Cimicidae). Although populations of the common bedbug, Cimex lectularius L., expanded in temperate regions of its original distribution, the tropical bedbug, C. hemipterus (F.), increased its abundance in warmer regions, where it also had been historically distributed. However, C. hemipterus has recently been observed to be expanding to other areas, e.g. North Australia, Middle East, the United States and Russia. In other parts of Europe, few sporadic and ephemeral introductions of C. hemipterus were recorded until recently. We conducted an extensive sampling of European bedbug populations starting in 2002 and found that C. hemipterus has recently become locally established. Among 566 examined infestations, nearly all of which involved C. lectularius, C. hemipterus occurred in six infestations collected since 2019. In at least three cases, the social background of inhabitants of the infested properties indicated that tropical bedbugs likely spread within local communities. Using cytochrome oxidase subunit I, we linked five of the infestations to the most common haplotype found globally, and one to an African haplotype. In all infestations, we observed two kdr-associated mutations in the sodium channel gene, which are also commonly found across the world.

International audience; Phylogeny and classification The worldwide family Rhinotermitidae, or subterranean termites, comprises 15 genera and more than 300 species. They occupy an intermediate position between the so-called "lower" and "higher" termites and so are often referred to as "intermediate" termites (1). The Rhinotermitidae appears to be paraphyletic, with most researchers placing the clade with Coptotermes and Heterotermes as a sister group to the Termitidae. Some researchers regard the Serritermitidae as paraphyletic within the Rhinotermitidae-Termitidae clade, while others place it as a basal group of Rhinotermitidae, near other basal groups such as Rhinotermes, Prorhinotermes, and Schedorhinotermes. Other researchers feel that Serritermitidae lies at the crossroads of worker caste evolution in termites, between the lower termites and the Rhinotermitidae+Termitidae clade. The most basal rhinotermitid taxa, such as Rhinotermes, diverged from the other lower termites less than 100 MA ago. The latest literature reviews indicate that the well-known, more derived genera Reticulitermes and Coptotermes+Heterotermes consistently form two distinct clades in a monophyletic branch within the family (2). These three genera account for more than half the species in Rhinotermitidae (184 of 305) and are the best studied within the family. The native ranges of these three genera (Reticulitermes, Coptotermes and Heterotermes) are all broad but fairly distinct. Coptotermes and Heterotermes are largely pantropical, although Heterotermes does not occur in Africa. Coptotermes is absent from the Nearctic and Palearctic regions. Reticulitermes naturally occurs exclusively within temperate areas. The Coptotermes+Heterotermes clade and Reticulitermes separated about 60 MA, according to various researchers. However, based on historical biogeography, modern Reticulitermes species resulted from cladogenesis and are highly taxonomically distinct. More ancient fossils of the different genera have been found in Europe, and they geologically date back to around 38 MYA. In a recent molecular phylogeny for Coptotermes, created using the complete mitochondrial genome, the genus is composed of numerous poorly supported branches. This result is partly due to the high level of synonymy in the present nomenclature and does not help clearly differentiate the species. However, speciation patterns were relatively clear in Australia, where this clade is the best defined. Consequently, this genus should be revised to deal with the high levels of synonymy in some locations (3).

Ants exhibit a striking variety of lifestyles, including highly specialist or mutualist species. The minute blind workers of the African genus Melissotarsus chew tunnels in live trees to accommodate their obligate partner scale insects. Their modified legs are adapted for tunneling, but are unsuited for walking outside, confining these ants to their initial host tree. Here, we investigated whether this unique lifestyle results in complex patterns of genetic diversity at different scales, from the same tree to different populations. Using 19 microsatellite markers, we assessed their mating strategy and colony structure among and across populations in South Africa. We showed that only one queen reproduces within a colony, mated with up to three males. Yet, several inseminated dealate queens are present in colonies; one probably replaces the older queen as colonies age. The reproduction of a single queen per colony at a given time results in genetic differentiation between colonies, even those located on the same tree. Overall, we discussed how the slow process of colony digging under the bark and the lack of worker patrolling above the bark might result in reduced competition between colonies and allow several secluded colonies to cohabit in a cramped space on a tree.

Reduced genetic diversity through inbreeding can negatively affect pathogen resistance. This relationship becomes more complicated in social species, such as social insects, since the chance of disease transmission increases with the frequency of interactions among individuals. However, social insects may benefit from social immunity, whereby individual physiological defenses may be bolstered by collective‐level immune responses, such as grooming or sharing of antimicrobial substance through trophallaxis. We set out to determine whether differences in genetic diversity between colonies of the subterranean termite, Reticulitermes flavipes, accounts for colony survival against pathogens. We sampled colonies throughout the United States (Texas, North Carolina, Maryland, and Massachusetts) and determined the level of inbreeding of each colony. To assess whether genetically diverse colonies were better able to survive exposure to diverse pathogens, we challenged groups of termite workers with two strains of a pathogenic fungus, one local strain present in the soil surrounding sampled colonies and another naïve strain, collected outside the range of this species. We found natural variation in the level of inbreeding between colonies, but this variation did not explain differences in susceptibility to either pathogen. Although the naïve strain was found to be more hazardous than the local strain, colony resistance was correlated between two strains, meaning that colonies had either relatively high or low susceptibility to both strains regardless of their inbreeding coefficient. Overall, our findings may reflect differential virulence between the strains, immune priming of the colonies via prior exposure to the local strain, or a coevolved resistance toward this strain. They also suggest that colony survival may rely more upon additional factors, such as different behavioral response thresholds or the influence of a specific genetic background, rather than the overall genetic diversity of the colony., Reduced genetic diversity through inbreeding can negatively affect pathogen resistance. We investigated this hypothesis in termites by testing whether the level of inbreeding within a colony affected the survival of workers challenged with two fungal pathogens. We found a bimodal distribution of colony survival, whereby colonies exhibit either high or low susceptibility. However, this difference was not explained by the level of inbreeding within the colony, suggesting that colony immunity may rely more on a specific genetic background, rather than its overall genetic diversity.

In recent years, bed bugs have experienced a remarkable resurgence on a near global scale. While reports have primarily focused on the common bed bug, Cimex lectularius (L.), which has resurged largely in temperate regions, in tropical regions the tropical bed bug, Cimex hemipterus (F.) (Hemiptera: Cimicidae), has reemerged as well. Recent reports of C. hemipterus introductions to subtropical and temperate regions, outside of the species natural distribution, suggest the potential for establishment and further spread. Establishment may be aided by insecticide resistance mechanisms, such as the presence of knockdown resistance (kdr)-associated mutations, which potentially confer resistance to pyrethroid, pyrethrin, and organochloride insecticides. Here, we present the first report of the detection and likely establishment of C. hemipterus in Honolulu, Hawaii, from samples collected in 2009 and 2019. Furthermore, through partial sequencing of the voltage-gated sodium channel, we report the presence of kdr-associated mutations in all samples. These findings have implications for the implementation of control strategies aimed at eradicating infestations.

Chemical communication is fundamental to success in social insect colonies. Species-, colony-, and caste-specific blends of cuticular hydrocarbons (CHCs) and other chemicals have been well documented as pheromones, mediating important behavioral and physiological aspects of social insects. More specifically, royal pheromones used by queens (and kings in termites) enable workers to recognize and care for these vital individuals and maintain the reproductive division of labor. In termites, however, no royal-recognition pheromones have been identified to date. In the current study, solvent extracts of the subterranean termite Reticulitermes flavipes were analyzed to assess differences in cuticular compounds among castes. We identified a royal-specific hydrocarbon—heneicosane—and several previously unreported and highly royal enriched long-chain alkanes. When applied to glass dummies, heneicosane elicited worker behavioral responses identical to those elicited by live termite queens, including increased vibratory shaking and antennation. Further, the behavioral effects of heneicosane were amplified when presented with nestmate termite workers’ cuticular extracts, underscoring the importance of chemical context in termite royal recognition. Thus, heneicosane is a royal-recognition pheromone that is active in both queens and kings of R. flavipes. The use of heneicosane as a queen and king recognition pheromone by termites suggests that CHCs evolved as royal pheromones ∼150 million years ago, ∼50 million years before their first use as queen-recognition pheromones in social Hymenoptera. We therefore infer that termites and social Hymenoptera convergently evolved the use of these ubiquitous compounds in royal recognition.

Ants are among the most successful species at invading new environments. Their success undeniably comes from their various modes of reproduction and colony breeding structures, which influence their dispersal ability, reproductive potential, and foraging strategies. Almost all invasive ant species studied so far form supercolonies, a dense network of interconnected nests comprising numerous queens, without aggression toward non‐nestmates. This strategy results in invasive colonies that are able to grow extremely fast and large while avoiding intraspecific competition, allowing them to monopolize environmental resources and outcompete native species. Here, we developed and used 10 microsatellite markers to investigate the population structure and breeding system of the dark rover ant Brachymyrmex patagonicus Mayr in its introduced range. We determined whether this species exhibits a supercolonial structure by assessing whether different nests belonged to the same genetic colony. We inferred its dispersal ability by investigating isolation by distance and estimated the numbers of queens per colonies and mating per queen through parent‐offspring inferences. We found that most of the colonies of B. patagonicus were comprised of a single nest, headed by a single queen. Each nest was distinct from one another, without isolation by distance, which suggests strong dispersal ability through nuptial flights. These features are commonly observed in noninvasive and native ant species, but they are surprising for a successful invasive ant, as they strongly differ from other invasive ants. Overall, we discuss how this seemingly unfavorable strategy for an invasive ant might favor the invasive success of the dark rover ant in the United States.

Much of the bluetongue (BT) and epizootic hemorrhagic disease (EHD) research in North America focuses on white-tail deer and Culicoides sonorensis (Wirth & Jones) (Diptera: Ceratopogonidae), though several other biting midge species have been suggested as vectors. Culicoides stellifer (Coquillett) has been associated with hosts susceptible to hemorrhagic disease (HD), and more recently, specimens from Florida have tested positive for EHD and BT viral RNA. If C. stellifer is acting as a vector, this could have an impact on the distribution of HD in North America. To determine if gene flow is occurring across the range of C. stellifer within the southeast United States, a mitochondrial haplotype analysis was performed using the COI gene. Our haplotype network showed no population structure in C. stellifer from Florida, Texas, and South Carolina, as the overall genetic divergence between these sites was equal to the genetic divergence within each. We also compared these haplotypes to published sequences of C. stellifer collected in Ontario, Canada. Surprisingly, the genetic diversity of the flies from Ontario was two times greater than what was observed between the southeast U.S. collection sites. This considerable divergence could be evidence of a cryptic species. A better understanding of the connectivity between C. stellifer populations across all of North America will give insight into the distribution of HD. Our results show that gene flow is occurring between sites in the southeastern United States and potentially throughout the eastern distribution of the species.

Termites are social insects that live in colonies headed by reproductive castes. The breeding system is defined by the number of reproductive individuals in a colony and the castes to which they belong. There is tremendous variation in the breeding system of termites both within and among species. The current state of our understanding of termite breeding systems is reviewed. Most termite colonies are founded by a primary (alate-derived) king and queen who mate and produce the other colony members. In some species, colonies continue throughout their life span as simple families headed by the original king and queen. In others, the primary king and queen are replaced by numerous neotenic (nymph- or worker-derived) reproductives, or less commonly primary reproductives, that are descendants of the original founding pair leading to inbreeding in the colony. In still others, colonies can have multiple unrelated reproductives due to either founding the colonies as groups or through colony fusion. More recently, parthenogenetic reproduction has shown to be important in some termite species and may be widespread. A major challenge in termite biology is to understand the ecological and evolutionary factors driving the variation in termite breeding systems.

Simple Summary Subterranean termites cause damage to man-made structures around the world and are continuing to invade new areas. Current practices for controlling termites generally target a single colony as workers tunnel near these structures, and although they are effective in most instances, they never reduce the overall termite pressure in the surrounding area. An area-wide approach to pest management could offer a way of controlling termites at the population level. By eliminating all or most of the colonies within a given area, the threat of infestation decreases. We tracked individual termite colonies over time, before and after the introduction of termite baits, to assess how long these colonies remained active to determine if a termite-free area could be maintained with continued baiting. This baiting approach was successful in significantly reducing the overall termite population within a baited area. Abstract We investigated the use of termite baiting, a proven system of targeted colony elimination, in an overall area-wide control strategy against subterranean termites. At two field sites, we used microsatellite markers to estimate the total number of Reticulitermes colonies, their spatial partitioning, and breeding structure. Termite pressure was recorded for two years before and after the introduction of Trelona® (active ingredient novaluron) to a large area of one of the sites. Roughly 70% of the colonies in the treatment site that were present at the time of baiting were not found in the site within two months after the introduction of novaluron. Feeding activity of the remaining colonies subsequently ceased over time and new invading colonies were unable to establish within this site. Our study provides novel field data on the efficacy of novaluron in colony elimination of Reticulitermes flavipes, as well as evidence that an area-wide baiting program is feasible to maintain a termite-free area within its native range.

Royal recognition is a central feature of insect societies, allowing them to maintain the reproductive division of labor and regulate colony demography. Queen recognition has been broadly demonstrated and queen recognition pheromones have been identified in social hymenopterans, but not in termites. Here we describe behaviors that are elicited in workers and soldiers by neotenic queens and kings of the subterranean termite, Reticulitermes flavipes, and demonstrate the chemical basis for the behavior. Workers and soldiers readily perform a lateral or longitudinal shaking behavior upon antennal contact with queens and kings. When royal cuticular chemicals are transferred to live workers or inert glass dummies, they elicit antennation and shaking in a dose-dependent manner. The striking response to reproductives and their cuticular extracts suggests that royal-specific cuticular compounds act as recognition pheromones and that shaking behavior is a clear and measurable queen and king recognition response in this termite species.

Background: Social insects are among the most serious invasive pests in the world, particularly successful at monopolizing environmental resources to outcompete native species and achieve ecological dominance. The invasive success of some social insects is enhanced by their unicolonial structure, under which the presence of numerous queens and the lack of aggression against non-nestmates allow high worker densities, colony growth, and survival while eliminating intra-specific competition. In this study, we investigated the population genetics, colony structure and levels of aggression in the tawny crazy ant, Nylanderia fulva, which was recently introduced into the United States from South America. Results: We found that this species experienced a genetic bottleneck during its invasion lowering its genetic diversity by 60%. Our results show that the introduction of N. fulva is associated with a shift in colony structure. This species exhibits a multicolonial organization in its native range, with colonies clearly separated from one another, whereas it displays a unicolonial system with no clear boundaries among nests in its invasive range. We uncovered an absence of genetic differentiation among populations across the entire invasive range, and a lack of aggressive behaviors towards conspecifics from different nests, even ones separated by several hundreds of kilometers. Conclusions: Overall, these results suggest that across its entire invasive range in the U.S.A., this species forms a single supercolony spreading more than 2000 km. In each invasive nest, we found several, up to hundreds, of reproductive queens, each being mated with a single male. The many reproductive queens per nests, together with the free movement of individuals between nests, leads to a relatedness coefficient among nestmate workers close to zero in introduced populations, calling into question the stability of this unicolonial system in which indirect fitness benefits to workers is apparently absent. Fil: Eyer, Pierre André. Texas A&M University; Estados Unidos Fil: McDowell, Bryant. Texas A&M University; Estados Unidos Fil: Johnson, Laura N. L.. Texas A&M University; Estados Unidos Fil: Calcaterra, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para el Estudio de Especies Invasivas; Argentina Fil: Fernández, María Belén. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Shoemaker, Dewayne. University of Tennessee; Estados Unidos Fil: Puckett, Robert T.. Texas A&M University; Estados Unidos Fil: Vargo, Edward L.. Texas A&M University; Estados Unidos

Termites, as social insects, have a complicated life cycle in which the colony breeding structure, that is the number of and origin of reproductives in a colony, can vary in relation to age and environmental factors. In this study, we used genetic methods to characterize the breeding structure of three species of Reticulitermes from three sites in northwest Arkansas and compared two habitats: undeveloped, forested sites and developed, agricultural sites. We found 57.1% of R. flavipes (Kollar) in northwest Arkansas (n = 28) were simple families, 39.3% were extended families and 3.6% were mixed families. Similarly, for R. hageni Banks (n = 23), we found 58.3% simple families, 33.3% extended families, and 8.3% mixed families. All of the R. virginicus (Banks) samples (n = 5) were simple families. For R. flavipes and R. hageni, the percentage of extended families is intermediate to southeastern and northern USA populations, corresponding to the intermediate seasonality and climate in Arkansas. The level of inbreeding in Arkansas, estimated via FIT, was relatively high and similar to northern populations of Reticulitermes. There were significantly more extended family colonies at the developed site compared to the two undeveloped sites which contained more simple family colonies. This difference may occur as a strategy to cope with sparse resources in urban environments or as a consequence of different abiotic factors.

Studies describing the population genetic structure and breeding system of basal lineages of termite species remain rare. Such species, however, may reveal ancestral life history attributes potentially influential in the evolution of social life within the Isoptera. Through the development and application of microsatellite DNA loci, we investigated patterns of genetic diversity and differentiation within the dampwood termite Zootermopsis angusticollis collected from three geographically distinct locations in California, USA. Significant genetic differentiation was identified among all sites, which were located 40–150 km apart, and each site was found to represent unique populations with limited levels of gene flow. While Z. angusticollis alates have previously been described as being strong fliers, genetic evidence suggests limited dispersal, possibly due to habitat characteristics restricting long-range flights. Additionally, we characterize patterns of colony genetic structure and breeding system within both Z. angusticollis and its congener Z. nevadensis nuttingi. In Z. angusticollis, simple, extended, and mixed family colonies were observed. The frequency of simple families ranged from 16 to 64%, whereas mixed families were found in only two locations and at low frequencies. In contrast, Z. n. nuttingi, formed primarily extended family colonies. Estimates of relatedness suggest that monogamous pairs heading simple families consist of reproductives showing variable degrees of relatedness from unrelated to close relatives. Additionally, the effective number of neotenic reproductives appears to be low within extended families of both species.

Parthenogenesis in vertebrates is considered an evolutionary novelty. In snakes, all of which exhibit genetic sex determination with ZZ : ZW sex chromosomes, this rare form of asexual reproduction has failed to yield viable female WW offspring. Only through complex experimental manipulations have WW females been produced, and only in fish and amphibians. Through microsatellite DNA fingerprinting, we provide the first evidence of facultative parthenogenesis in a Boa constrictor , identifying multiple, viable, non-experimentally induced females for the first time in any vertebrate lineage. Although the elevated homozygosity of the offspring in relation to the mother suggests that the mechanism responsible may be terminal fusion automixis, no males were produced, potentially indicating maternal sex chromosome hemizygosity (WO). These findings provide the first evidence of parthenogenesis in the family Boidae (Boas), and suggest that WW females may be more common within basal reptilian lineages than previously assumed.

Newly molted female neotenic reproductives of the dampwood termite Zootermopsis angusticollis Hagen were allowed to mature in the presence of a neotenic male, a fixed number of larval helpers, and varying numbers of sibling neotenic queens to assess the impact of secondary polygyny to the individual and colony. Under monogyne conditions, neotenics developed more ovarioles per ovary and had higher individual fecundities after 60 d compared with females under polygyne conditions. Queens in groups of three females were able to gain more body mass than those in groups of five. Although the division of resources provided by helpers reduced individual female development and fecundity under polygyne conditions, it resulted in an overall increase in colony fecundity. In addition, neotenic females in polygynous colonies did not differ significantly in reproductive competence. There was no evidence that neotenics were attacked or injured by other reproductives or larval helpers, suggesting little if any reproductive competition among sibling queens. The physiological responses of neotenics to the increasing queen/worker ratio may have the benefit of enhancing the colony growth at the cost of the fecundity of individual queens.

Made available in DSpace on 2018-12-11T17:08:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-19 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) A termite colony is usually founded by a pair of alates, the primary reproductives, which produce all the nestmates. In some species, secondary reproductives appear to either replace the primaries or supplement colony reproduction. In termites, secondary reproductives are generally ergatoids derived from workers or nymphoids derived from nymphs. Silvestritermes euamignathus is a termite species that forms multiple nymphoid reproductives, and to date it was hypothesized that these secondary reproductives were the progeny of the primary founding reproductives.We developed markers for 12 microsatellite loci and used COI mitochondrial DNA (mtDNA) to genotype 59 nymphoid neotenics found in a colony of S. euamignathus to test this hypothesis. Our results showed that nymphoids of S. euamignathus are not all siblings. The microsatellite analysis suggests that the secondary reproductives derived from a minimum of four different pairs of reproductives belonging to at least two different matrilines. This is the first record of non-sibling secondary reproductives occupying the same nest in a higher termite. These unrelated reproductives might be the result of either pleometrotic colony foundation or colony fusion. Laborat�rio de Cupins Departamento de Biologia Instituto de Bioci�ncias Univ Estadual Paulista-UNESP, Campus Rio Claro, Avenida 24A, 1515, Bela Vista Instituto de Ci�ncias Agr�rias Universidade Federal deUberl�ndia-UFU Campus Monte Carmelo, Avenida Goi�s, 2000, Vila Nova Department of Entomology North Carolina State University-NCSU, Campus Box 7613 Department of Entomology Texas A and M University, 2143 TAMU Laborat�rio de Cupins Departamento de Biologia Instituto de Bioci�ncias Univ Estadual Paulista-UNESP, Campus Rio Claro, Avenida 24A, 1515, Bela Vista FAPESP: 2012/23898-0 FAPESP: 2014/25857-4 CNPq: 305539/2014-0

We analyzed tandem-running pairs of the termites Reticulitermes flavipes and Reticulitermes virginicus utilizing 13 and 12 microsatellite loci, respectively. Newly formed pairs in both species were significantly related to one another, but this average relatedness was considerably higher in R. flavipes (0.130 vs 0.060). These average relatedness levels resulted from some tandem pairs forming between nestmate termites: more than one quarter of all R. flavipes pairs (26.1%) met this criterion, while this was the case for only about one of every 20 R. virginicus pairs (5.1%). The likelihood that termites paired with siblings was inversely related to the inferred dispersal ability of the two species. FST, measured over identical spatial scales, was significantly higher in R. flavipes (0.034) than in R. virginicus (0.008). A comparison in R. flavipes of the observed proportion of nestmate pairs observed during tandem running vs the proportion found in established colonies revealed a significant excess of close relatives when pairs were first formed. There are two possible causes of this discrepancy: inbreeding depression (ID) may eliminate inbred colonies early in development, or related pairs may part late in the tandem-running phase or after it is completed. The latter explanation of inbreeding avoidance implies either historical or contemporary ID, and these results therefore suggest that, either directly or indirectly, ID could be a more potent force in the evolution of termite mating systems than is generally appreciated.

We assessed colony and population structure in three French populations of the termite Reticulitermes grassei using eight polymorphic microsatellite loci. Although most colonies contained the offspring of multiple, highly related replacement reproductives (complex families), some contained the offspring of a single pair of reproductives (simple families), and the proportion of such colonies varied across populations. Populations also showed variability in the numbers of reproductives within complex families; the F-statistics of these families in one population were consistent with having upwards of 100 replacement reproductives, while in another population these colonies contained fewer than 10 pairs of reproductives. Colony boundaries in all populations were well defined, in spite of reports of a widespread breakdown in nestmate recognition and unicolonial populations of R. grassei from these regions in France. A second unexpected finding was a lack of significant isolation by distance among colonies within populations, indicating that colony reproduction by budding was rare or absent. The lack of this form of colony reproduction even within populations where it is expected to be common suggested that the propensity for colony budding may not be as common as suggested by the literature.

Temporal and spatial analyses are seldom utilized in the study of colony genetic structure, but they are potentially powerful methods which can yield novel insights into the mechanisms underlying variation in breeding systems. Here we present the results of a study which incorporated both of these dimensions in an examination of genetic structure of subterranean termites in the genus Reticulitermes (primarily R. flavipes). Most colonies of this species (70%) were simple families apparently headed by outbred primary reproductives, while most of the remaining (27% of the total) colonies contained low effective numbers of moderately inbred reproductives. Mapping the spatial distribution of colony foraging sites over time revealed that despite the high colony density, the absolute foraging boundaries of most R. flavipes colonies were persistent and exclusive of other conspecific colonies, which suggests that this species is more territorial than has been implied by laboratory studies of intraspecific aggression. Nevertheless, we found a single colony (3% of all colonies) which contained the offspring of more than two unrelated reproductives. Although other studies have also described subterranean termite colonies with a similarly complex genetic composition, we demonstrate here that such colonies can form under natural conditions via the fusion of whole colonies. This study underscores how repeated sampling from individual colonies over time and space can yield information about colony spatial and genetic structure that cannot be obtained from conventional analyses or sampling methods.

Colony and population genetic structure was determined for Reticulitermes flavipes (Kollar) and Reticulitermes virginicus (Banks) collected from Sentricon Termite Colony Elimination System monitoring stations at an apartment complex in Raleigh, NC. Once in each of 2000, 2001, and 2002, samples of termites were collected from monitoring stations just before the installation of bait tubes containing 0.5% hexaflumuron. Twenty workers from each sample were genotyped at five microsatellite loci. Comparison of worker genotypes among samples provided unambiguous colony associations. Analysis of worker genotypes within colonies coupled with estimates of F-statistics and nestmate relatedness showed that three fourths (30) of the 41 R. flavipes colonies and all three of the R. virginicus colonies were simple families headed by pairs of outbred monogamous reproductives. The remaining R. flavipes colonies were extended families, apparently headed by a few neotenic reproductives. Most colonies appeared to be ...

Studies were conducted on the physiological and hormonal changes following the release of alates from developmentally suppressive pheromones produced by mature queens of the fire ant Solenopsis invicta Buren. Winged virgin queens were removed from the pheromonal signal and placed in colony fragments. The time for dealation, degree of ovarian development, and biosynthesis rate and whole body content of juvenile hormone (JH) were measured. The production rate and content of JH were highly correlated. Dealation and the initiation of oviposition corresponded to peak production of JH. JH production rose sharply following separation from the natal nest, peaking after 3 days. After 8 days of isolation, JH production gradually subsided to levels similar to that found in pre-release queens, but began to increase again after 12 days. Mature queens had highly elevated levels of JH relative to recently dealate females, probably reflecting the increased reproductive capability of these older females. The results support the hypothesis that the pheromone released by functional queens inhibits reproduction in virgin alates by suppressing corpora allata activity and the production of JH.

International audience; Factors promoting the establishment and colonization success of introduced populations in new environments constitute an important issue in biological invasions. In this context, the respective role of pre-adaptation and evolutionary changes during the invasion process is a key question that requires particular attention. This study compared the colony breeding structure (i.e. number and relatedness among reproductives within colonies) in native and introduced populations of the subterranean pest termite, Reticulitermes flavipes. We generated and analysed a data set of both microsatellite and mtDNA loci on termite samples collected in three introduced populations, one in France and two in Chile, and in the putative source population of French and Chilean infestations that has recently been identified in New Orleans, LA. We also provided a synthesis combining our results with those of previous studies to obtain a global picture of the variation in breeding structure in this species. Whereas most native US populations are mainly composed of colonies headed by monogamous pairs of primary reproductives, all introduced populations exhibit a particular colony breeding structure that is characterized by hundreds of inbreeding reproductives (neotenics) and by a propensity of colonies to fuse, a pattern shared uniquely with the population of New Orleans. These characteristics are comparable to those of many invasive ants and are discussed to play an important role during the invasion process. Our finding that the New Orleans population exhibits the same breeding structure as its related introduced populations suggests that this native population is pre-adapted to invade new ranges.

Wolbachia are cytoplasmically inherited bacteria that induce a variety of effects with fitness consequences on host arthropods, including cytoplasmic incompatibility, parthenogenesis, male-killing and feminization. We report here the presence of Wolbachia in native South American populations of the fire ant Solenopsis invicta, but the apparent absence of the bacteria in introduced populations of this pest species in the USA. The Wolbachia strains in native S. invicta are of two divergent types (A and B), and the frequency of infection varies dramatically between geographical regions and social forms of this host. Survey data reveal that Wolbachia also are found in other native fire ant species within the Solenopsis saevissima species complex from South America, including S. richteri. This latter species also has been introduced in the USA, where it lacks Wolbachia. Sequence data reveal complete phylogenetic concordance between mtDNA haplotype in S. invicta and Wolbachia infection type (A or B). In addition, the mtDNA and associated group A Wolbachia strain in S. invicta are more closely related to the mtDNA and Wolbachia strain found in S. richteri than they are to the mtDNA and associated group B Wolbachia in S. invicta. These data are consistent with historical introgression of S. richteri cytoplasmic elements into S. invicta populations, resulting in enhanced infection and mtDNA polymorphisms in S. invicta. Wolbachia may have significant fitness effects on these hosts (either directly or by cytoplasmic incompatibility) and therefore these microbes potentially could be used in biological control programmes to suppress introduced fire ant populations.

Camponotus femoratus is an abundant and behaviorally dominant ant in lowland Amazonian rainforests, where this species participates in a complex and obligate seed-dispersal mutualism. C. femoratus typically cohabits with another ant species Crematogaster levior in an apparently amiable but poorly understood interaction. Despite these outstanding characteristics, the population genetics and dispersal patterns of C. femoratus are unknown. We isolated eight polymorphic microsatellite loci for C. femoratus from a genomic library enriched for di-, tri-, and tetra-nucleotide repeats. We detected 2 to 17 alleles per locus, with levels of observed heterozygosity ranging from 0.286 to 0.714.

Despite recognition of the western drywood termite, Incisitermes minor (Hagen), as one of the most economically important and destructive termite species in the USA, both its population and colony breeding structure genetically remain unclear. Here, we present primer sequences and initial characterization for 15 polymorphic microsatellite loci. In a sample of 30 individuals, representing six geographically distinct locations collected in California, USA, three to 15 alleles were detected segregating per locus. Within a single population observed heterozygosity ranged from 0.050 to 0.866.

Throughout Amazonia, the ant Crematogaster levior is known for its participation in a complex ant-garden mutualism with the ant Camponotus femoratus and several species of epiphytic plants for which it plays an important role in seed viability. We isolated nine polymorphic microsatellite loci for C. levior from a genomic library enriched for di-, tri-, and tetra-nucleotide repeats. Two to 14 alleles were detected per locus, with levels of observed heterozygosity ranging from 0.103 to 0.785.

Studies on the role of juvenile hormone (JH) in adult social Hymenoptera have focused on the regulation of two fundamental aspects of colony organization: reproductive division of labor between queens and workers and age-related division of labor among workers. JH acts as a gonadotropin in the primitively eusocial wasp and bumble bee species studied, and may also play this role in the advanced eusocial fire ants. However, there is no evidence that JH acts as a traditional gonadotropin in the advanced eusocial honey bee or in the few other ant species that have recently begun to be studied. The role of JH in age-related division of labor has been most thoroughly examined in honey bees. Results of these studies demonstrate that JH acts as a "behavioral pacemaker," influencing how fast a worker grows up and makes the transition from nest activities to foraging. Hypotheses concerning the evolutionary relationship between the two functions of JH in adult eusocial Hymenoptera are discussed.

The fungus-growing subterranean termite Odontotermes formosanus Shiraki (Isoptera: Termitidae) is a destructive pest in Southeast Asia. To facilitate studies on the biology, ecology, and control of O. formosanus, we isolated and characterized nine novel microsatellite loci from a mixed partial genomic library of O. formosanus and the sympatric Macrotermes barneyi Light enriched for di-, tri-, and tetranucleotide repeats. We screened these loci in three populations of O. formosanus from China. All loci were polymorphic. Three loci showed heterozygote deficit possibly because of the presence of null alleles. The remaining six loci with 4-15 alleles per locus and an average observed heterozygosity of 0.15-0.60 across populations were used for population genetic analysis. Populations from different provinces (Guangdong, Jiangxi, and Hubei) were genetically differentiated, but the genetic distance between populations was surprisingly small (FST: 0.03-0.08) and the gene flow was considerable (Nem: 3-8), despite the geographical distance being300 km. Genetic diversity within populations was low (allelic richness: 5.1-6.3) compared with other subterranean dwelling termites, but consistent with the diversity in species of the family Termitidae. Microsatellite markers developed for O. formosanus will allow further studies to examine the phylogeography, population genetic and colony breeding structure, dispersal ranges, and size of foraging territories in this and closely related species, as well as aid in assessing treatment success.

Bed bugs (Cimex lectularius L.) are a resurgent pest worldwide and infestations within the United States are increasing at a rapid rate. Because of the physical and psychological discomfort inflicted by their blood feeding habits, and allergies and secondary infections associated with bites, bed bugs are recognized as a significant public health problem. Although bed bug infestations are spreading and becoming more prevalent, we have a poor understanding of their dispersal patterns and sources of infestation. To help fill this gap, we conducted a genetic study of 21 bed bug infestations from the eastern United States, nearly all of which came from single rooms within residences. We genotyped samples comprised of 8-10 individuals per infestation at nine polymorphic microsatellite loci. Despite high genetic diversity across all infestations, with 5-17 alleles per locus (mean = 10.3 alleles per locus), we found low genetic diversity (1-4 alleles per locus) within all but one of the infestations. These results suggest that nearly all the studied infestations were started by a small propagule possibly consisting of a singly mated female and/or her progeny, or a female mated with multiple males that were highly related to her. All infestations were strongly genetically differentiated from each other (mean pairwise F(ST) between populations = 0.68) and we did not find strong evidence of a geographic pattern of genetic structure, indicating infestations located in closer proximity to each other were nearly as genetically differentiated as those located hundreds of kilometers away. The high level of genetic diversity across infestations from the eastern United States together with the lack of geographically organized structure is consistent with multiple introductions into the United States from foreign sources.

The fungus-growing termite, Macrotermes gilvus (Hagen), an indigenous species from Southeast Asia distributed from Myanmar to Indonesia and the Philippines, offers great potential as an ecological model system to elucidate the effects of geography on gene flow within this region. We used next generation sequencing (Roche 454 pyrosequencing) to identify microsatellite markers from the genomic DNA of M. gilvus. A modest sequencing volume generated 34,122 reads, with 1,212 (3.6%) reads contains microsatellites with di-, tri-, tetra-, penta-, and hexa-nucleotide repeat motifs. Thirty-seven loci were selected for primer development and tested for polymorphism across 22 colonies of M. gilvus. Eleven loci were found to be polymorphic with 2-4 alleles per locus. Observed and expected heterozygosities ranged between 0.091-0.727 and 0.090-0.540, respectively. Cross taxa amplification was successful across a panel of four related termite species and four multiplex groups were designed for future population genetic studies. These markers will open new avenues for the study of phylogeography and population genetics of this fungus-growing termite. This study also has effectively demonstrated the use of 454 pyrosequencing for the rapid development of informative microsatellite markers from a termite genome.

Studies were conducted on the physiological mode of action and mode of perception of a queen pheromone that inhibits dealation (wing-shedding) and ovary development in virgin queens of the fire ant Solenopsis invicta. Winged virgin queens were removed from the pheromonal signal (queen) to compare the response time for dealation, a behavioral response, and ovary development, a physiological response. Dealation was always accompanied by some degree of ovary development, whereas some individuals exhibited slightly developed ovaries before dealation occurred, suggesting that ovary development precedes dealation by several hours to a day. The response time of virgin queens following extinction of the pheromonal signal was highly variable and was related to colony source and body weight. Individuals from monogyne (single functional queen) colonies were more responsive than those from polygyne (multiple functional queens) colonies, a result consistent with the high cumulative levels of queen pheromone in the latter colonies. Virgin queens treated topically with the juvenile hormone (JH) analogue, methoprene, dealated and developed their ovaries in the presence of the pheromone (queen), suggesting that the pheromonal mode of action involves the suppression of JH titers. To obtain more precise information on the physiological processes underlying the inhibition of ovary development, vitellogenin titers were determined for virgin queens and functional (egg-laying) queens. Despite having undeveloped ovaries, virgin queens had vitellogenin titers that were as elevated as those of functional queens. This suggests that the effect of the low JH titers resulting from the primer pheromone is on the uptake of vitellogenin by the oocytes rather than on vitellogenin synthesis. The possible mode of perception of the inhibitory pheromone was also investigated. Virgin queens whose antennae had been removed dealated in the presence of the queen, suggesting that the pheromone acts by stimulating sensory cells in the antennae. The results are incorporated into a general model for the mode of action of the queen primer pheromone.

Until recently, facultative automictic parthenogenesis within the squamate reptiles exhibiting ZZ:ZW genetic sex determination has resulted in single reproductive events producing male (ZZ) or female (ZW) offspring. With the recent discovery of viable parthenogenetically produced female (WW) Boa constrictors, the existence of further parthenogenetic events resulting in WW females was questioned. Here, we provide genetic evidence for consecutive virgin births by a female Colombian rainbow boa (Epicrates maurus), resulting in the production of WW females likely through terminal fusion automixis. Samples were screened at 22 microsatellite loci with 12 amplifying unambiguous products. Of these, maternal heterozygosity was observed in 4, with the offspring differentially homozygous at each locus. This study documents the first record of parthenogenesis within the genus Epicrates, a second within the serpent lineage Boidae, and the third genetically confirmed case of consecutive virgin births of viable offspring within any vertebrate lineage. Unlike the recent record in Boa constrictors, the female described here was isolated from conspecifics from birth, demonstrating that males are not required to stimulate parthenogenetic reproduction in this species and possibly other Boas.

The hallmark of social insects is their caste system: reproduction is primarily monopolized by queens, whereas workers specialize in the other tasks required for colony growth and survival. Pheromones produced by reining queens have long been believed to be the prime factor inhibiting the differentiation of new reproductive individuals. However, there has been very little progress in the chemical identification of such inhibitory pheromones. Here we report the identification of a volatile inhibitory pheromone produced by female neotenics (secondary queens) that acts directly on target individuals to suppress the differentiation of new female neotenics and identify n-butyl-n-butyrate and 2-methyl-1-butanol as the active components of the inhibitory pheromone. An artificial pheromone blend consisting of these two compounds had a strong inhibitory effect similar to live neotenics. Surprisingly, the same two volatiles are also emitted by eggs, playing a role both as an attractant to workers and an inhibitor of reproductive differentiation. This dual production of an inhibitory pheromone by female reproductives and eggs probably reflects the recruitment of an attractant pheromone as an inhibitory pheromone and may provide a mechanism ensuring honest signaling of reproductive status with a tight coupling between fertility and inhibitory power. Identification of a volatile pheromone regulating caste differentiation in a termite provides insights into the functioning of social insect colonies and opens important avenues for elucidating the developmental pathways leading to reproductive and nonreproductive castes.

A possible stimulatory effect of overwintering on gyne development in Iridomyrmex humilis (Mayr) was investigated. Although gyne-potent larvae are present in the nest throughout the year, small queenless colony fragments composed of freshly overwintered ants (collected in late winter or early spring) produced 3–8 times more gynes than comparable fragments made up of non-freshly overwintered ants (collected at other times of the year). Apparently, this stimulatory effect of overwintering acts on both the developmental potential of larvae and the tendency of workers to rear sexually competent larvae as gynes; queenless colony fragments in which either the brood or workers were freshly overwintered produced more gynes than fragments composed of non-freshly overwintered workers or brood but fewer than fragments containing both brood and workers freshly overwintered. This increased sexualization potential of larvae due to overwintering is enough to overcome weak pheromonal inhibition of queens associated with low queen number; a single queen in a large freshly overwintered colony fragment is insufficient to inhibit gyne development, whereas ten queens are totally inhibitory. In non-freshly overwintered colony fragments one queen is completely inhibitory. Variability in egg developmental potential according to queen age does not appear to play a major role in the seasonal production of gynes, because at least some eggs of very young queens (less than 3 weeks old) are capable of gyne development. In the field this stimulatory effect of overwintering is superimposed on a seasonal fluctuation in the combined strength of pheromonal queen control. In southern France, gynes are produced only in spring where they arise primarily from overwintered larvae just after a sharp drop in queen number, and presumably the total level of inhibitory queen pheromone, due to the massive execution of queens by workers.

Social Hymenoptera are general models for the study of parent-offspring conflict over sex ratio, be- cause queens and workers frequently have different reproductive optima. The ant Pheidole pallidula shows a split distribution of sex ratios with most of the colonies producing reproductives of a single sex. Sex ratio spe- cialization is tightly associated with the breeding system, with single-queen (monogynous) colonies producing male- biased brood and multiple-queen (polygynous) colonies female-biased brood. Here, we show that this sex special- ization is primarily determined by the queen's influence over colony sex ratio. Queens from monogynous colonies produce a significantly more male-biased primary sex ratio than queens from polygynous colonies. Moreover, queens from monogynous colonies produce a significantly lower proportion of diploid eggs that develop into queens and this is associated with lower rate of juvenile hormone (JH) production compared to queens from polygynous colonies. These results indicate that queens regulate colony sex ratio in two complementary ways: by determining the proportion of female eggs laid and by hormonally biasing the devel- opment of female eggs into either a worker or reproductive form. This is the first time that such a dual system of queen influence over colony sex ratio is identified in an ant.

Termites (Isoptera) comprise a large and important group of eusocial insects, yet, in contrast to the eusocial Hymenoptera (ants, bees, wasps), the breeding systems of termites remain poorly understood. In this study, I inferred the breeding system of the subterranean termite Reticulitermes flavipes based on colony and population genetic structure as determined from microsatellite and mitochondrial DNA markers. Termites were sampled from natural wood debris from three undisturbed, forested sites in central North Carolina. In each site, two transects separated by 1 km were sampled at approximately 15-m intervals. A total of 1272 workers collected from 57 collection points were genotyped at six microsatellite loci, and mitochondrial DNA haplotype was determined for a subset of these individuals using either restriction fragment length polymorphism or sequence variation in the AT-rich region. Colonies appeared to be localized: workers from the 57 collection points represented 56 genetically distinct colonies with only a single colony occupying two collection points located 15 m apart. Genetic analysis of family structure and comparisons of estimates of F-statistics (F(IT), F(IC), F(CT)) and coefficients of relatedness (r) among nestmate workers with results of computer simulations of potential breeding systems suggested that 77% of all colonies were simple families headed by outbred monogamous pairs, whereas the remaining colonies were extended (inbred) families headed by low numbers of neotenics (about two females and one male) who were the direct offspring of the colony founders. There was no detectable isolation by distance among colonies along transects, suggesting that colony reproduction by budding is not common and that dispersal of reproductives during mating flights is not limited over this distance. Higher-level analysis of the microsatellite loci indicated weak but significant differentiation among sites (F(ST) = 0.06), a distance of 16-38 km, and between transects within sites (F(ST) = 0.06), a distance of 1 km. No significant differentiation at either the transect or site level was detected in the mitochondrial DNA sequence data. These results indicate that the study populations of R. flavipes have a breeding system characterized by monogamous pairs of outbred reproductives and relatively low levels of inbreeding because most colonies do not live long enough to produce neotenics, and those colonies that do generate neotenics contain an effectively small number of them.

The haplodiploid sex-determination system of ants gives rise to conflict between queens and workers over colony sex ratios, and the female-biased allocation ratios seen in many species suggest that workers often prevail in this conflict. We exchanged queens between male- and female-specialist colonies of the fire ant Solenopsis invicta. These exchanges quickly reversed the sex-ratio biases of adopting colonies. The sex ratio of queen-laid eggs differed strongly between male- and female-specialist colonies. These findings suggest that queens can force workers to raise male sexuals by limiting the number of female brood and help to explain why sex investment ratios lie between the queen and worker equilibria in this and many other ant species., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

The poison sac of the fire ant Solenopsis invicta is the only identified glandular source of pheromones produced by a functional ant queen. This structure, which contains the poison gland, has previously been shown to be the source of a releaser pheromone that mediates queen recognition and tending by workers. The poison sac has also been demonstrated to be the source of a primer pheromone that inhibits winged, virgin queens from shedding their wings (dealating) and developing their ovaries. To determine if the poison sac was the only source of these pheromones, we excised the poison sac from queens and observed whether operated queens retained their pheromonal effects. In a first experiment, the poison sac was removed from functional (egg-laying) queens which were then paired with unoperated nestmate queens in small colonies. Counts of the workers surrounding each queen two weeks after the operation showed that queens without poison sac were as effective as their unoperated nestmates in attracting worker retinues. In a second experiment, we removed the poison sacs of virgin queens which had not yet begun laying eggs and thus had not begun producing queen pheromone. After allowing them to develop their ovaries, these individuals produced amounts of queen recognition pheromone comparable to those secreted by unoperated or sham operated virgin queens as determined by bioassay. Testing the head, thorax and abdomens of functional queens separately revealed that the head was the most attractive region in relation to its relative surface area. Bioassays of extracts of two cephalic glands—the mandibular gland and postpharyngeal gland—showed that the postpharyngeal gland is a second source of the queen recognition pheromone. Finally, we found that virgin queens whose poison sacs were removed before they began producing queen pheromone initiated production of a primer pheromone that inhibits winged virgin queens from dealating, indicating that this pheromonal effect also has an additional but as yet undetermined source. These results parallel those on the honey bee in which several of the pheromonal effects of functional queens appear to have multiple glandular sources.

Decrease in individual reproductive output with increasing numbers of reproductives is a general feature of social insect colonies. The previously described negative relationship between the fecundity of individual queens and number of resident queens in polygyne (multiple-queen) colonies of the fire ant Solenopsis invicta appears to result from mutual pheromonal inhibition. In an experimental test for the presence of fecundity reducing pheromones, corpses of functional (egg-laying) queens were found to effectively inhibit the fecundity of functional queens, suggesting that queen-produced pheromones suppress egg production in such queens. Evidence concerning a possible mechanism mediating this inhibition was also obtained. Treatment of queens with methoprene, a juvenile hormone (JH) analog, increased ovary development, suggesting that fecundity in functional queens may be mediated by the level of endogenous JH. These findings are consistent with the occurrence of mutual pheromonal inhibition among queens achieved by suppression of endogenous JH titers.

Both field observations and laboratory experiments have suggested that queens of I. humilis inhibit the production of new queens (gynes). Using small colony fragments, laboratory experiments were conducted to determine the means by which this inhibition is achieved. The addition of queen corpses to queenless fragments effectively inhibited the production of gynes, suggesting that a queen inhibitory primer pheromone is involved. This inhibitory influence was removed when corpses were washed in pentane, lending further support to the pheromonal hypothesis. Adult gynes (winged virgin queens) were not inhibitory, whereas young dealated mated queens of the same age were, suggesting that only inseminated queens produce the pheromone. Daily addition of eggs to queenless units did not appear to have a strong inhibitory influence, indicating that the lower worker/larva ratios associated with the presence of an egg-laying queen in such colony fragments does not greatly influence the production of sexuals. Pheromonal inhibition of gyne development appears to be achieved mainly by preventing the sexualization of bipotent female larvae, probably by affecting the brood-rearing behavior of workers. In addition, queens may also cause the execution of female larvae after they have become sexualized. In nearly all cases, the addition of a living queen to previously queenless units containing gyne larvae caused workers to execute one or more of these larvae within 24 h. In some cases queens were also seen attacking gyne larvae. The addition of queen corpses resulted in the execution of gyne larvae, suggesting that a queen pheromone mediates, at least in part, this execution behavior of workers. These results show that I. humilis queens exert control over the production of gynes in two ways: (1) by preventing the sexualization of female larvae and (2) by killing female larvae after they have become sexualized. A queen primer pheromone appears to be involved in both processes. Queen behavior also plays a role, at least in the execution of gyne larvae. This queen control over the production of gynes, probably mostly pheromonal, appears to operate strongly in the field where gynes are produced only in spring just after a sharp drop in the inhibitory queen influence due to the massive execution of queens by the workers.