A newly-discovered mode of colony founding among fire ants

Summary Queen ants start new colonies either unassisted by workers (independent founding), assisted by workers from their natal nest (dependent founding), or assisted by the workers of other species (dependent, socially parasitic). The monogyne form of the fire ant,Solenopsis invicta, founds independently in summer, but in the fall it also produces a few sexuals some of which overwinter, then fly and mate in early spring. These overwintered queens lack the nutritional reserves and behaviors for independent colony founding. Rather, they seek out unrelated, mature, orphaned colonies, enter them and exploit the worker force to found their own colony through intraspecific social parasitism. Success in entering orphaned colonies is higher when these lack overwintered female alates of their own. When such alates are present, orphaning causes some to dealate and become uninseminated replacement queens, usually preventing entry of unrelated, inseminated replacement queens. Such colonies produce large, all-male broods. Successful entry of a parasitic queen robs the host colony of this last chance at reproductive success. Only overwintered sexuals take part in this mode of founding.     

蚁巢表层土壤温湿度对不同发育阶段红火蚁数量的影响(英文)

红火蚁一种攻击性非常强的外来入侵蚂蚁,可对入侵地的农业生产、生态系统、人体健康和公共安全等产生负面影响,温度和湿度是影响其生长和发育的重要环境因子.本研究评估了红火蚁蚁巢表层土壤温、湿度对红火蚁幼虫、有翅蚁蛹和有翅蚁成虫数量的影响.结果表明,随着土壤温度的升高,幼虫、有翅蚁蛹和有翅蚁成虫的数量都呈先升高后下降的趋势.当...     

Identification and action of juvenile hormone III from sexually mature alate females of the red imported fire ant,Solenopsis invicta

Analysis of extracts of hemolymph obtained from sexually mature alate females of Solenopsis invicta from monogyne colonies resulted in identification of juvenile hormone III (JH III). The average amount of JH III was 0.32±0.04 pmol/μmolof hemolymph. Topical application of 0.038 pmol of JH III was sufficient to stimulate alates to shed their wings in the presence of the queen. The time in which alates were induced to dealate decreased linearly with increasing concentrations of JH III from 0.038 to 3.8 pmol. However, higher JH III concentrations deviated from linearity and did not reach dealation times comparable with those that occur after mating flights. Thus, it appears that the mechanism of dealation that occurs when female alates are out of the influence of their queen is different from the one associated with mating flights. Application of 0.42 μmol of precocene II inhibited dealation of alates in queenless colonies. However, this inhibition was reversed after applying 38 pmol JH III to precocene-treated alates. The sizes of corpora allata (CA) from sexuals treated with JH III did not differ from those of controls. However, the sizes of CA were reduced in alates treated with precocene II. The results indicated that JH was important to dealation.     

Annual life cycle and timing of male-egg production in the antColobopsis nipponicus (Wheeler)

Summary Life history parameters, including colony boundary, number of queens in a colony, seasonal change in colony-member composition and seasonal change in male-egg production were investigated for the arboreal antColobopsis nipponicus in the field. Colonies were shown to be typically monogynous and polydomous, with several different colonies inhabiting the same tree. The queen and workers overwinter only with larvae, which grow rapidly into new adults during early summer. Male-destined eggs were produced throughout the warm season with a conspicuous peak in summer that coincided with adult production. It is suggested that this might be related to seasonal changes in the food available to the queen.     

The responses of Apis mellifera jemenitica to different artificial queen rearing techniques

In the current study, we investigated if any variations exist in acceptance rate of grafted larvae and quality of queens reared in different queen cell cup sizes, between wet and dry grafting and between queen right and queen less conditions of A. m. jemenitica colonies. The acceptance rate of grafted larvae in different queen cell cup sizes (7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm) were varying from 69 to 71% and the variations were not significant among the different queen cups sizes but averagely lower than the acceptances recorded for other races. Out of the 172 dry grafted larvae, only 56.4% of them were accepted while in wet grafting out of 174 grafted larvae 77.01% were accepted. Regarding the rate of sealing, 48.84% and 71.84% of them sealed for dry and wet grafts, respectively. The observed variation in the rate of acceptance and sealing were significant (N = 346, df = 1, P < 0.0001) between the two techniques. However, there was no significant difference in fresh weight of emerged queens between the two grafting methods. Out of the 324 grafted larvae given to queen right and queen less starter colonies each; 106 (32.72%) and 252 (73.68%) were accepted in queen right and queen less starter colonies, respectively and the variation was highly significant at P < 0.0001. The total number of sealed pupae were 82 (25.31%) and 216 (63.16%) for queen right and queen less colonies, respectively and the variations was significant at P < 0.0001. From the study it can be concluded that A. m. jemenitica colonies can rear significantly more queens under wet grafting and in queen less colonies conditions than dry grafting and queen right conditions     

我国大陆红火蚁不同等级和虫态过冷却点的测定

了解我国红火蚁Solenopsis invicta Buren的耐低温能力并为其风险分析提供科学依据,本文对采自我国4个地点红火蚁蚁群中不同等级和虫态的过冷却点,以及不同季节和室内不同饥饿程度的工蚁过冷却点进行了测定。结果表明：蚁群中不同等级和虫态的过冷却点差异显著。工蚁成虫的过冷却点（－11.8±0.4℃）显著低于有翅雌蚁（－8.1±0.6℃）及蚁后（－7.9±0.5℃）,工蚁蛹和幼虫的过冷却点分别为－13.6±0.3℃和－12.1±0.4℃,蚁后蛹和幼虫的分别为－13.3±0.3℃和－12.2±0.3℃。工蚁蛹的过冷却点均显著低于其成虫和幼虫。蚁后蛹与其幼虫的过冷却点没有显著差异,但与其成虫的差异显著。同一未成熟期不同等级之间的也没有显著差异;不同季节的工蚁过冷却点有显著差异,其中以春季的最高（－4.3±0.2℃）,夏季（－6.6±0.2℃）、秋季（－9.4±0.1℃）的次之,冬季的（－12.0±0.3℃）最低;深圳、珠海、广州和陆川4个地理种群的工蚁过冷却点在春、秋和冬季无显著差异,但夏季陆川种群的过冷却点显著低于其他3个种群的（P<0.05）。饥饿可使工蚁的过冷却点明显升高,但大工蚁的过冷却点较小工蚁升高的幅度更大,饥饿15 d后的大工蚁比饥饿前的过冷却点升高了7.0℃,而小工蚁仅升高了4.9℃。这些结果为评价红火蚁在我国潜在的传播风险提供了理论依据。     

Social control of egg-laying rate in queens of the fire ant, Solenopsis invicta*

ABSTRACT Social control of egg-laying rate in queens of the fire ant (Solenopsis invicta Buren) was studied by experimental manipulation of the number of larvae, pupae and workers in colonies, and the age and size of larvae and workers. Workers and pupae do not stimulate oviposition by queens. The number of fourth instar larvae, on the other hand, bears a positive log-log relationship to the queen's egg-laying rate. Such larvae are needed both to stimulate and maintain oviposition. Their withdrawal results, within 48 h, in a decline in queen oviposition almost to zero. Their addition to broodless nests results in peak laying in about 4 days. Larvae in the first three stadia and early in the fourth stadium have a much lower effect upon queen fecundity. Sexual larvae are only c. 5% as stimulating on a weight basis, but equivalent on an individual basis. Several associated measures are positively correlated to egg-laying rate: weight of the queen, the number of her vitellogenic follicles per ovariole, total vitellogenic follicles, the time she spends feeding and (usually) the number of workers in the retinue that cares for her. The egg volume is negatively correlated with laying rate, so that queens lay more eggs for the same expenditure of material as laying rate increases. As body size of workers increases, they become less effective in transmitting the larval stimulation to the queen, but worker age has no effect on this ability. For a given number of larvae, queens in small, naturally growing colonies lay fewer, larger eggs than do queens in experimental colonies, but their fecundity increases more rapidly in relation to number of larvae. When larvae are fed vital-dyed food in one experimental colony, and then transferred to an undyed colony, the dye is rapidly transferred to worker crops, and into the queen's eggs, indicating bulk movement of material from larvae to workers to the queen and eggs. Large larvae are more effective at this than small larvae. Fourth instar larvae may be a digestive and metabolic caste that processes protein for egg production by the queen. If that is the case, the queen and fourth instar larvae are linked in a positive feedback loop. Either the logarithmic relation of fecundity to larval numbers or physical limits of the queen may set the maximum egg-laying rate, and thus determine maximum colony size. The data do not allow a clear choice between these alternatives.     

The influence of queens of the antParatrechina flavipes on daughter and non-daughter workers, for the suppression of sexual production

The influence that the queen ofParatrechina flavipes (Smith) (Hymenoptera: Formicidae) has upon workers was investigated in field and laboratory nests. There was no significant difference in sexual production, either of gynes or males, between field queenright and queenless nests of the ant. A replicated laboratory experiment revealed that workers lay fewer eggs and rear fewer sexual larvae in the presence of their mother queen, while this reduction is not observed in workers with influence of non-mother queens. The results seem to support the queen's signal hypothesis by Keller & Nonacs (1993). The contradiction is explained by workers rearing sexuals in queenless satellite nests. There exists a probably complex regulation of the transfer of larvae between satellite and mother nests.     

Queen-worker conflict over sex ratio: A comparison of primary and secondary sex ratios in the Argentine ant,Iridomyrmex humilis

We compare the primary sex ratio (proportion of haploid eggs laid by queens) and the secondary sex ratio (proportion of male pupae produced) in the Argentine ant Iridomyrmex humilis with the aim of investigating whether workers control the secondary sex ratio by selectively eliminating male brood. The proportion of haploid eggs produced by queens was close to 0.5 in late winter, decreased to less than 0.3 in spring and summer, and increased again to a value close to 0.5 in fall. Laboratory experiments indicate that temperture is a proximate factor influencing the primary sex ratio with a higher proportion of haploid eggs being laid at colder temperatures. Production of queen pupae ceased in mid-June, about three weeks before that of male pupae. After this time only worker pupae were produced. During the period of production of sexuals, the proportion of male pupae ranged from 0.30 to 0.38. Outside this period no males were reared although haploid eggs were produced all the year round by queens. Workers thus exert a control on the secondary sex ratio by eliminating a proportion of the male brood during the period of sexual production and eliminating all the males during the remainder of the cycle. These data are consistent with workers preferring a more female-biased sex ratio than queens. The evolutionary significance of the production of male eggs by queens all the year round is as yet unclear. It may be a mechanism allowing queen replacement in the case of the death of the queens in the colony.     

Reproductive conflicts in polyandrous and polygynous ant Formica sanguinea

The occurrence of multiple reproductives within an ant colony changes the balance between indirect fitness benefits and reproductive competition. We test whether the number of matings by an ant queen (polyandry) correlates negatively with the number of reproductive queens in the colony (polygyny), whether the patrilines and matrilines differ in their contribution to the sexual and worker progeny and whether there is an overall reproductive skew. For these aims, we genotyped both worker and sexual offspring from colonies of the ant Formica sanguinea in three populations. Most colonies were monogynous, but eight (11%) were polygynous with closely related queens. Most queens in the monogynous colonies (86%) had mated with multiple males. The effective paternity was lower than the actual number of mates, and the paternity skew was significant. Furthermore, in some monogynous colonies, the patrilines were differently represented in the worker pupae and sexual pupae produced at the same time. Likewise, the matrilines in polygynous colonies were differently present in worker pupae and male offspring. The effective number of matings by a queen was significantly lower in polygynous colonies (mean m_e = 1.68) than in monogynous colonies (means 2.06–2.61). The results give support to the hypotheses that polyandry and polygyny are alternative breeding strategies and that reproductive competition can lead to different representation of patrilines and matrilines among the sexual and worker broods.     

Influence of immature queen honeybees (Apis mellifera) on queen rearing and foraging

ABSTRACT. Providing queenless colonies with five queen cells containing larvae or pupae diminished the number of queen cells and queen cell cups subsequently produced, but not as effectively as the provision of a mated laying queen. Immature queens were more effective than the mature queens in stimulating pollen collection, but were less effective in stimulating nectar collection.     

Elimination of sexual brood in the Argentine antLinepithema humile: queen effect and brood recognition

Mated queens of the antLinepithema humile (Iridomyrmex humilis Mayr) introduced into dequeened colony fragments rearing sexual brood elicited worker aggression resulting in queen larvae being bitten and eliminated. By contrast, male larvae were spared. Regarding queen brood, killing mainly concerned small and medium sized larvae. A large proportion of the large larvae escaped extermination, and prepupae and pupae were spared. These data suggest that workers were able to discriminate sex, caste and age of the brood. That a queen pheromone may be involved was shown by experiments using whole or cut corpses that were either rinsed or not rinsed in pentane. The pheromone eliciting worker aggressive behaviour was shown to act over a short distance, suggesting that it is somewhat volatile. Similarities and differences between this new queen pheromone and other known queen pheromones acting on queen production or worker attraction are discussed as well as the origin of the signals underlying the recognition of the larval classes.     

Photoperiodic influence on the body mass of bumblebee, Bombus terrestris and its copulation duration

Abstract:  The body mass of Bombus terrestris individuals is an important trait for their behavioural performance and colony organization. In this study, colonies were reared under four different photoperiodic regimes, viz. 0 : 24, 8 : 16, 16 : 8 and 24 : 0 h light : darkness (L : D) at 28°C and 50% relative humidity. The changes in body mass were observed at the stages of larvae, pupae and on the day of adult eclosion. Both the wet and dry mass of sexuals gradually decreased with increasing day length. The relationship between body mass and copulation duration revealed that copulation duration was negatively correlated with male body mass, but positively with queen body mass. Higher number of matings by males resulted in significantly higher duration of copulation.     

Standard metabolic rate of the fire ant,Solenopsis invicta Buren: effects of temperature,mass, and caste

Standard metabolic rates of S. invicta workers, males, female alates, larvae and pupae were determined using closed-system respirometry. Vdot;(O(2)) (ml h(-1)) of all castes and life stages scaled with temperature and mass. Differences between castes and life stages are discussed in light of their different life histories and the different functions of these stages within the colony. Workers, female alates, male alates, larvae and pupae had mass-specific Vdot;(O(2)) (ml O(2) g wet weight(-1) h(-1), corrected to 25 degrees C) of 0.404+/-0.023, 0.316+/-0.010, 0.674+/-0.024, 0.291+/-0.020, and 0.227+/-0.015 (mean+/-SE), respectively. Measurement of CO(2) and O(2) made possible the examination of temperature and mass effects on respiratory quotient (RQ), as well as accurate transformation of O(2) consumption to metabolic rate (&mgr;W) for comparison with other ant species. Mass-specific metabolic rates of S. invicta females and workers compare favorably with data from 17 other ant species, but metabolic rates of males (177%) and pupae (42%) fall above and below predicted rates, respectively. Several equations relating temperature and mass to Vdot;(O(2)) are presented.     

Performance of Myrmica ant colonies is correlated with the presence of social parasites

1. The performance of ant colonies depends on different factors such as nest site, colony structure or the presence of pathogens and social parasites. Myrmica ants host various types of social parasites, including the larvae of Maculinea butterflies and Microdonmyrmicae (Schönrogge) hoverfly. How these social parasites affect host colony performance is still unexplored. 2. It was examined how the presence of Maculinea teleius Bergsträsser, Maculinea alcon (Denis & Schiffermüller), and M. myrmicae larvae, representing different feeding and growth strategies inside host colonies, is associated with worker survival, the number of foragers, and colony productivity parameters such as growth and reproduction. 3. It was found that the presence of social parasites is negatively associated with total colony production and the production of ant larvae and gynes. Male production was lower only in nests infested by M. teleius, whereas the number of worker pupae was significantly higher in all types of infested colonies than in uninfested colonies. Laboratory observations indicated that nests infested by Maculinea larvae are characterised by a higher number of foragers compared to uninfested nests but we did not find differences in worker survival among nest types. 4. The observed pattern of social parasite influence on colony productivity can be explained by the feeding strategies of parasitic larvae. The most negative effect was found for M. teleius, which feeds on the largest host brood and eliminates a high number of sexual forms. The strong, adverse influence of all studied parasite species on gyne production may result in low queen production in Myrmica populations exposed to these social parasites.     

Production of winged and wingless males in the ant, <Emphasis Type="Italic">Cardiocondyla minutior</Emphasis>

Summary Wingless (ergatoid) males of the tramp ant Cardiocondyla minutior attack and kill their young ergatoid rivals and thus attempt to monopolize mating with female sexuals reared in the colony. Because of the different strength of local mate competition in colonies with one or several reproductive queens, we expected the production of new ergatoid males to vary with queen number. Sex ratios were mostly female-biased, but in contrast to the sympatric species C. obscurior (Cremer and Heinze, 2002) neither the percentage of ergatoid males nor of female sexuals among the first 20 sexuals produced varied considerably with queen number. As in C. obscurior, experimental colony fragmentation led to the production of winged males, whereas in unfragmented control colonies only ergatoid males eclosed.Received 3 December 2003; revised 20 February 2004; accepted 23 February 2004.     

A statistical study of the population of the tropical mound building termiteOdontotermes redemanni (Wasmann)

A statistical analysis of the population of the tropical mound building termite,Odontotermes redemanni, shows the existence of significant peaks in the populations of worker, soldier and nymphs in different phases during June to September. The population trends of the sexual nymphs and others show a close parallelism and this associationship is quite significant from a biological point of view. The population structure within the mounds is intimately associated with the multiplicative phase of the mounds and the peak in the overall population mostly occurs when sexual nymphs are produced in large numbers. These sexual nymphs develop into alates and fly out to establish new colonies. The ability of the de-alate sexuals in the mounds to produce the sexual nymphs and other castes in large numbers during the multiplicative phase of the mounds is probably genetically determined. Various statistical tests have been tried to interpret the biological factors associated with the population dynamics of this termite.     

Colony structure and reproduction in the ant, Leptothorax acervorum

We analyzed the sociogenetic organization of the ant (Leptothoraxacervorum) from Nrnberger Reichswald in Southern Germany. Accordingto relatedness estimates from allozyme analyses, virgin femalesexuals produced in polygynous colonies were on average fullsisters, whereas workers in a pooled sample of polygynous colonieswere significantly less closely related. Rather than attributingthis to reproductive hierarchies among nest mate queens, weshow how this phenomenon could result from seasonal fluctuationsof colony composition and a decline of the production of femalesexuals in polygynous colonies. We suggest that by queen adoptionand emigration or budding, colonies easily switch from monogynyto polygyny and vice versa. Due to the long developmental timeof sexual larvae, colonies that have become polygynous onlyrecently will still produce the female sexual progeny of a singlequeen. In older polygynous nests, fewer and fewer female sexualsare produced, but colonies may fragment into monogynous budsin which the production of female sexuals may begin again. Relatednessestimates, dissection results, and field observations supportthis suggestion. This pattern of cyclical monogyny and polygynykeeps nest mate relatedness high and probably facilitates colonyfounding in boreal habitats. Preliminary data suggest that thepattern of the production of sexuals in colonies of L. acervorumfits the expectations of sex allocation theory.     

Colony age, neighborhood density and reproductive potential in harvester ants

At about age 5 years, colonies of the harvester ant, Pogonomyrmex barbatus, begin to produce winged, sexual forms (alates) that mate in large annual aggregations. We examined how colony age and neighborhood density affect the numbers, body mass, and body fat of alates produced by 172 colonies ranging in age from 4 to 17 years. Over one-third (36%) of all colonies produced no alates. Failure to reproduce was independent of colony age. Of those colonies that did produce alates, older colonies produced more alates than younger colonies. Older colonies produced lighter female alates (in dry mass), but the total biomass of additional alates produced by older colonies far outweighed the reduced allocation to female alate body mass. Body fat content was much higher in female alates (36.0% on average) than in males (3.7% on average). Alate body fat content was not related to colony age. The fitness of female alates may be related to their fresh body mass; that of females captured after mating and reared in the laboratory was positively correlated with egg-laying rate, although not with the total number of eggs in the first brood. Neighborhood density was not related to alate number, mass, or fat content, in contrast to the results of a 1995 study at the site, in which alate numbers were negatively related to neighborhood density. Thus the influence of crowding on reproductive output appears to vary from year to year, perhaps in response to variation in rainfall and food supply. Alate output by individual colonies was correlated among years. These results suggest that a few, older colonies dominate the pool of reproductives year after year. Received: 11 May 1998 / Accepted: 19 December 1998     

Sex ratio conflict and worker production in eusocial hymenoptera

The best known of the conflicts occurring in eusocial Hymenoptera is queen-worker conflict over sex ratio. So far, sex ratio theory has mostly focused on optimal investment in the production of male versus female sexuals, neglecting the investment in workers. Increased investment in workers decreases immediate sexual productivity but increases expected future colony productivity. Thus, an important issue is to determine the queen's and workers' optimal investment in each of the three castes (workers, female sexuals, and male sexuals), taking into account a possible trade-off between production of female sexuals and workers (both castes developing from diploid female eggs). Here, we construct a simple and general kin selection model that allows us to calculate the evolutionarily stable investments in the three castes, while varying the identity of the party controlling resource allocation (relative investment in workers, female sexuals, and male sexuals). Our model shows that queens and workers favor the investment in workers that maximizes lifetime colony productivity of sexual males and females, whatever the colony kin structure. However, worker production is predicted to be at this optimum only if one of the two parties has complete control over resource allocation, a situation that is evolutionarily unstable because it strongly selects the other party to manipulate sex allocation in its favor. Queens are selected to force workers to raise all the males by limiting the number of eggs they lay, whereas workers should respond to egg limitation by raising a greater proportion of the female eggs into sexual females rather than workers as a means to attain a more female-biased sex allocation. This tug-of-war between queens and workers leads to a stable equilibrium where sex allocation is between the queen and worker optima and the investment in workers is below both parties' optimum. Our model further shows that, under most conditions, female larvae are in strong conflict with queens and workers over their developmental fate because they value their own reproduction more than that of siblings. With the help of our model, we also investigate how variation in queen number and number of matings per queen affect the level of conflict between queens, workers, and larvae and ultimately the allocation of resource in the three castes. Finally, we make predictions that allow us to test which party is in control of sex allocation and caste determination.