New data on Nasutitermes from French Guiana (Isoptera: Termitidae: Nasutitermitinae)

Nasutitermes octopilis, N. ephratae, N. similis, N. guayanae, N. guayanae form columbicus, and N. surinamensis are cited for the first time from French Guiana on the basis of the soldier and worker castes. The mandible of major worker of N. surinamensis, of small soldier of N. costalis, small worker of N. ephratae, small and major worker of N. similis, and of the major worker of N. guayanae [“form” columbicus (Holmgren, 1910)] are described for the first time.     

A comparison of the reproductive ability of <Emphasis Type="Italic">Varroa destructor</Emphasis> (Mesostigmata:Varroidae) in worker and drone brood of Africanized honey bees (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Colony infestation by the parasitic mite, Varroa destructor is one of the most serious problems for beekeeping worldwide. In order to reproduce varroa females, enter worker or drone brood shortly before the cell is sealed. To test the hypothesis that, due to the preference of mites to invade drone brood to reproduce, a high proportion of the mite reproduction should occur in drone cells, a comparative study of mite reproductive rate in worker and drone brood of Africanized honey bees (AHB) was done for 370 mites. After determining the number, developmental stage and sex of the offspring in worker cells, the foundress female mite was immediately transferred into an uninfested drone cell. Mite fertility in single infested worker and drone brood cells was 76.5 and 79.3%, respectively. There was no difference between the groups (X ² = 0.78, P = 0.37). However, one of the most significant differences in mite reproduction was the higher percentage of mites producing viable offspring (cells that contain one live adult male and at least one adult female mite) in drone cells (38.1%) compared to worker cells (13.8%) (X ² = 55.4, P < 0.01). Furthermore, a high level of immature offspring occurred in worker cells and not in drone cells (X ² = 69, P < 0.01). Although no differences were found in the percentage of non-reproducing mites, more than 74% (n = 85) of the mites that did not reproduce in worker brood, produced offspring when they were transferred to drone brood.     

Male Behavior and Regulation of Worker Mating in a Ponerine Ant, Pachycondyla (Bothroponera) sp. (Hymenoptera: Formicidae)

Male behavior and regulation of worker mating were observed in Indonesian Pachycondyla sp. The colonies had some mated workers but only one gamergate (mated and egg-laying workers). Males frequently tried to mate with workers in their natal nests irrespective of worker age and dominance rank, however, workers never accepted mounting of nestmate males. Worker mating occurred only under the gamergateless condition with alien males.     

Taxonomy, distribution and nesting biology of species of the genus Dolichovespula (Hymenoptera, Vespidae)

The genus Dolichovespula consists provisionally of 18 species. Aerial nest site characteristics have been established for seven species but most of these species show flexibility in their choice of nest sites and two species often nest in shallow subterranean situations. Colony length is usually just over 3 months to approximately 4 months, but at lower latitudes may extend to more than 5 months. Mature colony size is usually approximately 1000 cells with more large cells than small cells. Parasitized colonies have a shorter colony cycle and smaller colonies. During the production of the sexual brood the larva/worker ratio reaches its lowest value of approximately 2.5 larvae per worker. Colonies often have upper mixed combs of small and large cells. Total adult production is usually less than 2000 adults. Colonies of D. arenaria and D. norwegica may specialize in mainly producing males or queens. Variations in mature colony size and production of queens is probably a consequence of the number of workers present, particularly early in the colony cycle.     

Losses of workers and reproductives in colonies of the paper waspPolistes riparius (Hymenoptera: Vespidae) due to the parasitic waspLatibulus sp.

1. Losses in workers and reproductives due to the ichneumonid parasitoid Latibulus sp. were determined in a haplometrotic, temperate paper wasp, Polistes riparius, during a 5-year study.
2. Fifty-four to 79% of pre-emergence nests were parasitized on worker brood, resulting in a worker loss of 25–31% on average. Worker brood reared in outer cells were much more often parasitized than those in central ones, possibly because outer cells are more accessible to the parasitoid. Infestation of worker brood was not random but aggregated among nests.
3. Seventy-eight to 100% of nests were parasitized on reproductive brood, and lost 10–34% of reproductives.
4. The number of emerged workers positively correlated with that of reproductives produced and that of cells made during the season. This suggests that worker loss reduces reproductive output of colonies. Hence, the parasitoid can reduce colonial reproductive output not only by killing reproductive brood but by reducing worker force.

     

Variation of ommatidia number as a function of worker size inCamponotus pennsylvanicus (DeGeer) (Hymenoptera: Formicidae)

Summary The relation of worker size to ommatidia number was examined in the polymorphic antCamponotus pennsylvanicus (DeGeer). Linear regression described this relationship as:Y = 260.9 + 113.6×; whereYis ommatidia number andX is head width. A log-log regression described this relationship as:Y = 323.5 + 286.9*logX(r ² = 0.98). This analysis indicated an allometric relation of ommatidia number to head width, where ommatidia numbers increase at a slower rate than head width. This relationship is discussed in terms of ethotypes associated with worker morphotypes, and the possible mechanisms regulating polymorphic development.     

Midgut bacterial communities in the giant Asian honeybee (Apis dorsata) across 4 developmental stages: A comparative study

Bacterial communities are known to play important roles during the developmental stages of insects, but current knowledge of bacteria associated with the midgut of Apis dorsata, the giant Asian honeybee, is limited. Using polymerase chain reaction‐denaturing gradient gel electrophoresis analysis (PCR‐DGGE) and 16S rRNA sequencing, the aim of this study was to determine the dynamics of bacterial community structure across four A. dorsata life stages in different geographical locations. The results reveal that bacterial diversity increased as the bee progressed through larval stage to newly emerged worker and old worker. However, in the pupal stage, no bands identified as bacteria could be observed. Overall, 2 bacterial phyla (Proteobacteria and Firmicutes) and 4 classes (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Bacilli) were identified, but the frequency varied among the different stages and locations. The classes of Gammaproteobacteria and Bacilli dominated among larval, newly emerged worker and old worker developmental stages.     

Observation of group recruitment to prey in a primitive ponerine ant,Amblyopone sp. (reclinata group) (Hymenoptera: Formicidae)

Summary Group recruitment during foraging was observed in a primitive ponerine ant,Amblyopone sp. (reclinata group) under laboratory condition. Workers searched for prey singly; however, if a item of prey was stung by a worker, other ants joined the attack. After the prey became immobile, one of the workers laid a trail directly toward the nest. This scout worker recruited additional workers (between 3 and 33). They formed a single file procession to the point of prey capture, and cooperatively transported the prey. A scout worker could stimulate nest workers to leave the nest without direct contact, and the recruited workers could trace the trail without guidance by the scout worker. This is the first report of recruitment behavior during foraging in the primitive antAmblyopone.     

Worker thermal tolerance in the thermophilic ant Cataglyphis cursor (Hymenoptera, Formicidae)

In the thermophilic ant genus Cataglyphis, species differing in their physical caste system have developed alternative mechanisms to face extreme heat by physiological and/or behavioural adaptations. In this study, we tested whether thermal tolerance is related to worker size in the ant Cataglyphis cursor that presents intermediate worker size compared with previously studied species (size range 3.5–10 mm). Thermal tolerance at two temperatures was tested in the laboratory on colonies originating from two habitats (seaside versus vineyard), known to differ in average worker size. As expected large workers were more resistant to high temperature than small workers, but the effect of worker size on thermal resistance was less pronounced under the more extreme temperatures. The pattern of thermal tolerance was similar in the two habitat types. After controlling for worker size, worker thermal tolerance significantly varied amongst colonies, but this variation was not related to colony size. Our results suggest that a higher thermal tolerance can confer an advantage to larger workers especially during foraging and are discussed in the context of the evolution of worker size in ants.     

Corrigendum: Shear adhesive performance of leaf-cutting ant workers (Atta cephalotes)

In our previous article, Shear adhesive performance of leaf-cutting ant workers (Atta cephalotes), a technical error occurred when calculating shear adhesive performance divided by tarsal pad area of worker ants carrying leaves (Stark, A. Y., Davis, H. R., & Harrison, W. K. (2019). Biotropica, 51(4), 572–580). Shear adhesive performance of worker ants carrying leaves was mistakenly divided by the tarsal pad area of workers riding on leaves. This has slightly changed our results. After correcting for this error, there is now no statistically significant difference in shear adhesive performance divided by tarsal pad area of worker ants riding on leaves and those carrying leaves. Shear adhesive performance of these groups remains statistically different than soldiers, and our original results (shear adhesive performance of all three groups differ from one another) are consistent with the reported trend in the original article using true pad area for each individual (rather than estimated). We list below the pages and figures in the original article that this correction applies to. All authors agree with this change, apologize for their error, and appreciate the opportunity granted by the editors and publisher to make this correction. Our original conclusion, that there is variation in shear adhesive performance per unit area among worker roles of Atta cephalotes, is still supported by these corrected results.     

The potential for worker reproduction in the ant <Emphasis Type="Italic">Aphaenogaster cockerelli</Emphasis> and its absence in the field

A reproductive division of labor between subordinates and established reproductives is a hallmark of eusociality. In most groups, however, workers retain some reproductive capabilities. Across insect societies, measures of successful worker reproduction in the presence of a queen, with few exceptions, indicate that worker reproduction is kept at very low levels. There are, however, certain colony-level characteristics that may influence the degree to which worker reproduction is promoted, such as queen number, queen mating frequency, and physical presence of a queen in species with multiple nesting sites (polydomy). In this study, the level of worker reproduction in field colonies of the ant species Aphaenogaster cockerelli was measured. A. cockerelli is a monogynous and polydomous species, so worker reproduction across nesting sites was investigated. None of the 297 males sampled provided any evidence of worker reproduction. Worker reproduction would have been detectable if it was present at or above a level of 1.5 % of the total males per colony. An effective mating frequency for queens of this species was found to be 1.03. Although A. cockerelli colonies have many colony-level factors potentially promoting worker reproduction (workers with active, trophic egg-producing ovaries, a single singly-mated queen, workers who are physically separated from the queen), it is evident that worker reproduction is highly regulated. Synthesizing the extensive amount of policing and fertility signaling data previously reported on this species, A. cockerelli is presented as case study for how worker reproduction is repressed and cooperation is maintained in insect societies.     

First record of Diversitermes diversimiles (Silvestri, 1901) from French Guiana (Isoptera: Termitidae,Nasutitermitinae)

Previously known from Brazil, North Argentina, Paraguay, and Bolivia, Diversitermes diversimiles (Silvestri, 1901) is cited for the first time from French Guiana, on the basis of the soldier and worker castes. The digestive tube of its worker is photographied for the first time.     

Lethal infection thresholds of Paenibacillus larvae for honeybee drone and worker larvae (Apis mellifera)

We compared the mortality of honeybee (Apis mellifera) drone and worker larvae from a single queen under controlled in vitro conditions following infection with Paenibacillus larvae, a bacterium causing the brood disease American Foulbrood (AFB). We also determined absolute P. larvae cell numbers and lethal titres in deceased individuals of both sexes up to 8 days post infection using quantitative real‐time PCR (qPCR). Our results show that in drones the onset of infection induced mortality is delayed by 1 day, the cumulative mortality is reduced by 10% and P. larvae cell numbers are higher than in worker larvae. Since differences in bacterial cell titres between sexes can be explained by differences in body size, larval size appears to be a key parameter for a lethal threshold in AFB tolerance. Both means and variances for lethal thresholds are similar for drone and worker larvae suggesting that drone resistance phenotypes resemble those of related workers.     

Alarm-recruitment behaviour in Pheidole militicida (Hymenoptera: Formicidae)

ABSTRACT.

• 1 Pheidole militicida Wheeler, a seed-harvesting species of the southwestern United States, possesses a major worker caste (soldiers) with unusually large heads. Previous work suggested that these large major workers are specialized defenders against large seed-harvesting species in the genus Pogonomyrmex.
• 2 Experimental introductions of Pogonomyrmex maricopa Wheeler and the omnivorous fire ant, Solenopsis xyloni McCook, demonstrate that P. militicida colonies alarm-recruit major workers against S.xyloni workers but not against the larger Pogonomyrmex workers.
• 3 P.militicida is the second species in which enemy-specific defence against Solenopsis fire ants has been detected. I suggest that the special role of Solenopsis as both competitor and predator in ant communities frequently favours major worker specialization against this genus.
• 4 Major workers of P.militicida and Pheidole dentata Mayr, the other species with enemy-specific defence against Solenopsis, are morphologically very different from one another. It is suggested that interspecific variation in major worker morphology is not necessarily associated with variation in behavioural specialization.

     

Notes on the biology of the Oriental amblyoponine ant Myopopone castanea: Queen‐worker dimorphism,worker polymorphism and larval hemolymph feeding by workers (Hymenoptera: Formicidae)

Queen‐worker dimorphism, worker polymorphism and worker behavior in the Oriental amblyoponine ant Myopopone castanea were studied. Queen body size was large (head width, 3.0 mm) with 24 to 32 ovarioles while workers showed a remarkable size variation in both body size (head width 1.48 to 2.18 mm) and ovariole number (6 to 22). Both head width and abdomen width showed allometric growth against thorax width. Workers performed larval hemolymph feeding as was described for Amblyopone silvestrii queens.     

A biometric study of seasonal variation in worker wasps (Hymenoptera: Vespidae)

The seasonal changes in some morphometric characters of worker wasps of Vespula vulgaris and Vespula germanica are described and discussed in relation to colony populations and economics.     

Community-level interactions and functional ecology of major workers in the hyperdiverse ground-foraging Pheidole (Hymenoptera, Formicidae) of Amazonian Ecuador

Ants of the genus Pheidole are abundant and hyperdiverse, particularly in Neotropical rainforests. Very little is known, however, about the degree of ecological and behavioral differentiation of coexisting species comprising Pheidole communities. Additionally, the ecological role of the major worker subcaste, thought to be significant to the diversification of Pheidole, is poorly understood. We investigated the ecology and behavior of a ground-foraging Pheidole community of at least 56 species in Amazonian Ecuador. Pheidole species differed strongly in tolerance to flooding, nest site usage, foraging range, major worker foraging, and control of baits, but not in daily activity or ability to discover baits. A molecular phylogeny based on mitochondrial DNA was characterized by poorly resolved basal relationships and long terminal branches, suggesting an ancient diversification of many Pheidole lineages. Comparison of well-supported sister species suggests that both phylogenetic history and ecologically induced differentiation contribute to interspecific variation in Amazonian Pheidole. Ground-nesting species had larger major workers than twig-nesting species, whereas dominant species with stronger recruitment had a higher proportional abundance of major workers at baits. Variation among species suggests the presence of behavioral groups within the Amazonian Pheidole community that appear to segregate according to nest site usage and/or tolerance to flooding disturbance. Our results suggest an important role for major worker differentiation in the diversification of Pheidole.     

Reproduction of Varroa destructor in worker brood of Africanized honey bees (Apis mellifera)

Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Africanized honeybee (AHB) (Apis mellifera) colonies in Yucatan, Mexico. Between February 1997 and January 1998 monthly records of the amount of pollen, honey, sealed worker and drone brood were recorded. In addition, mite infestation levels of adult bees and worker brood and the fecundity of the mites reproducing in worker cells were determined. The mean number of sealed worker brood cells (10,070 ± 1,790) remained fairly constant over the experimental period in each colony. However, the presence and amount of sealed drone brood was very variable. One colony had drone brood for 10 months and another for only 1 month. Both the mean infestation level of worker brood (18.1 ± 8.4%) and adult bees (3.5 ± 1.3%) remained fairly constant over the study period and did not increase rapidly as is normally observed in European honey bees. In fact, the estimated mean number of mites fell from 3,500 in February 1997 to 2,380 in January 1998. In May 2000 the mean mite population in the study colonies was still only 1,821 mites. The fertility level of mites in this study was much higher (83–96%) than in AHB in Brazil(25–57%), and similar to that found in EHB (76–94%). Mite fertility remained high throughout the entire study and was not influenced by the amount of pollen, honey or worker brood in the colonies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Local dynamics of worker activity of the invasive Vespula germanica and V. vulgaris (Hymenoptera: Vespidae) wasps in Argentina

1. The abundance of insects depends essentially on the reproductive success of individuals. In social insects, however, the abundance of sterile workers outside a nest depends on colony size but is also determined by ontogeny, nest demands, and local environmental factors. For invasive social wasps, the drivers of worker abundance are important because they determine the impact that these species have on the native systems, people, and their goods. 2. The aim of the present study was to understand the relative importance of endogenous and exogenous factors on the abundance of workers of populations of Vespula spp., by analysing 12 years of trap captures in NW Patagonia. This is the first attempt to model the activity levels of invasive Vespula spp. wasps over time in Argentina. 3. It was shown that between years, the worker activity of both vespids presents fluctuations, and that of V. germanica is determined by the spring mean temperatures. Within the flight season, V. germanica worker activity is affected by the relative abundance of workers in that year, whereas for V. vulgaris, activity it is affected by the relative abundance of both species that year. We found no relationship between individual weather variables and activity within a flight season for both wasps. 4. The patterns observed for Argentina are similar to those observed in all invaded temperate areas where Vespula spp. are established. This study provides useful information to understand the driving factors that affect Vespula spp. worker activity in Argentina. This could be a necessary step to develop plans to manage these invasive social insects.     

Foraging decisions of individual workers vary with colony size in the greenhead ant Rhytidoponera metallica (Formicidae, Ectatomminae)

Summary. The ability of worker ants to adapt their behaviour depending on the social environment of the colony is imperative for colony growth and survival. In this study we use the greenhead ant Rhytidoponera metallica to test for a relationship between colony size and foraging behaviour. We controlled for possible confounding ontogenetic and age effects by splitting large colonies into small and large colony fragments. Large and small colonies differed in worker number but not worker relatedness or worker/brood ratios. Differences in foraging activity were tested in the context of single foraging cycles with and without the opportunity to retrieve food. We found that workers from large colonies foraged for longer distances and spent more time outside the nest than foragers from small colonies. However, foragers from large and small colonies retrieved the first prey item they contacted, irrespective of prey size. Our results show that in R. metallica, foraging decisions made outside the nest by individual workers are related to the size of their colony.Received 23 March 2004; revised 3 June 2004; accepted 4 June 2004.