Nest architecture and colony size of the fungus-growing ant <Emphasis Type="Italic">Mycetophylax simplex</Emphasis> Emery, 1888 (Formicidae,Attini)

Detailed measurements on nest architecture and colony size of the fungus-growing ant Mycetophylax simplex Emery, 1888 (Formicidae, Attini) are reported for the first time, based on excavations of 55 nests from two sites in southern Brazil. All nests were subterranean, with a single entrance hole. Most nests consisted of two chambers, an upper and a lower chamber, but one and three-chamber nests were also found. The chambers were more cone-shaped than rounded, and located at a depth ranging from 4.0 cm to 32.5 cm below the nest entrance. The chamber dimensions generally increased as the depth of the chambers increased, and the lower chamber was mostly wider than the upper one. The fungus garden was always found resting on the chamber floor. The average colony size was 264.1 workers, ranging from 67 to 610 workers. Colonies produced most sexuals during the summer (from December to March) and a few during the winter (July). Direct observations showed that colonies were mostly monogynous, but more than one queen was recorded in two nests, suggesting that polygyny may also occur in this species. Received 30 November 2006; revised 20 April 2007; accepted 23 April 2007.     

Colony structure and sex allocation ratios in the ant <Emphasis Type="Italic">Temnothorax crassispinus</Emphasis>

Summary. We analyzed the impact of ecological parameters, such as nest density and nest site availability, on colony organization and investment patterns in two populations of the ant Temnothorax crassispinus, a parapatric sibling species of the well-studied T. nylanderi (Temnothorax was until recently referred to as Leptothorax (Myrafant); Bolton, 1993). As in T. nylanderi, sex allocation ratios were strongly associated with total sexual reproduction, i. e., nests with large sexual investment produced mainly female sexuals. Furthermore, nest site quality affected sex allocation ratios, with colonies from ephemeral nest sites producing a more male-biased sex allocation ratio than colonies from sturdy nest sites. In contrast to T. nylanderi, workers in colonies of T. crassispinus were mostly fullsisters both in a dense and a sparsely populated area, suggesting that colony fusion and colony usurpation are rare in this species. In addition, the presence of a queen in a local nest unit strongly influenced sex ratio decisions, in that these nests raised a more male biased allocation ratio compared to queenless nests. This also suggests that colony structure is more stable in T. crassispinus than in T. nylanderi. We conclude that sibling species, though often very similar in their morphology and ecological requirements, may nevertheless react very differently to ecological variation.Received 11 December 2003; revised 4 March 2004; accepted 19 April 2004.     

Both cooperation and nest position improve larval survival in the sweat bee, <Emphasis Type="Italic">Lasioglossum</Emphasis> (<Emphasis Type="Italic">Evylaeus</Emphasis>) <Emphasis Type="Italic">baleicum</Emphasis>

Nesting by multiple females in sweat bees raises the question of the benefits associated with grouping. Adult numbers of the sweat bee, Lasioglossum (Evylaeus) baleicum, exhibited variation within a nest population. The effects of adult number and nest position on larval survival were analyzed in a nest aggregation. Both variables independently affected larval survival, with the presence of multiple adults in a nest markedly improving survival rate. Nests located near the periphery of the aggregation of nests suffered high larval mortalities. Increased frequency of cell-inspection in multiple-female nests seems to be associated with a concomitant increase in larval cell protection from external predation. Such predation pressure was assumed, given the existence of an underground ant colony that employs a recruitment system while foraging in the study area.     

Physiological effects upon <Emphasis Type="Italic">Amblyomma americanum</Emphasis> (Acari: Ixodidae) infected with <Emphasis Type="Italic">Beauveria bassiana</Emphasis> (Ascomycota: Hypocreales)

Unfed adult Amblyomma americanum were exposed to the entomopathogenic fungus Beauveria bassiana. Ticks exposed to the fungus exhibited reduced survival and increased water loss as indicated by change in weight. Treated ticks survived 7.2 ± 0.22 days (mean ± SE) and controls survived 17.9 ± 0.73 days (P = 0.01; df = 57). At death, ticks exposed to the fungus had lost 25.2 ± 0.84% of their starting weight; control ticks had lost 14.1 ± 0.85% of their starting weight (P = 0.01; df = 96). Water loss was highest immediately following inoculation, although losses continued to be higher than in uninoculated ticks. This suggests that fungal penetration causes sufficient cuticle damage to cause desiccation, although other water-loss avenues exist, including increased time of spiracular opening. Additionally this study did not eliminate the possibility of a negative impact on water vapor uptake. This is the first study to investigate the effect of an entomopathogenic fungus on the water balance of a tick.     

Sociality in <Emphasis Type="Italic">Euglossa</Emphasis> (<Emphasis Type="Italic">Euglossa</Emphasis>) <Emphasis Type="Italic">viridissima</Emphasis> Friese (Hymenoptera,Apidae, Euglossini)

Euglossa viridissima is an orchid bee that forms both solitary and multiple female nests, making it a suitable species for the study of factors leading to diverse degrees of sociality in Euglossines. We conducted observations in eight reused nests (where a first generation of bees had been produced) kept in artificial boxes from the Yucatan Peninsula, Mexico. Five nests were reused (reactivated) by a single female (SFN), two nests reused by a mother and one daughter (MFN1) and one nest reused by the mother and two daughters (MFN2). No single nest was reactivated by unrelated females. The number of foraging trips, their duration and the duration of cell provisioning was not different between SFN and MFN. The overall production of cells per female was not different either between both types of nest. However, in MFN although all females did lay eggs, there was a reproductive skew in favor of the mother (95 and 45% of the brood produced in MFN1 and MFN2 respectively). She showed reproductive control of her daughters through oophagy and displaying threatening behavior when the daughters tried to open a cell where she had laid an egg. Brood losses to parasites (Anthrax sp. (Bom-byliidae) and Hoplostelis bivittata (Megachilidae)) were only found in SFN which possibly reflects and advantage of MFN in this respect. Our results coupled with other studies in Euglossa, reveal that a wide range of social behaviors occur in this genus, from solitary and communal to primitive reproductive division of labor. Multiple factors involving different levels of pressure imposed by food availability and parasites may favor such a diverse range of nesting behaviors. Interestingly, female associations in E. viridissima seem a result of kin selection that is enforced by coercion from mother females on their daughters. More studies are needed to shed light upon the social organization of Euglossa and other Euglossines and on their phylogenetic relationships in order to trace the origins of eusociality in Apidae. Received 12 February 2008; revised 25 June 2008; accepted 17 July 2008.     

Fungus garden platforms improve hygiene during nest establishment in <Emphasis Type="Italic">Acromyrmex</Emphasis> ants (Hymenoptera,Formicidae, Attini)

Physically isolating organisms from disease agents should reduce the likelihood of disease transmission and infection, and increase survival and growth, particularly in more vulnerable, early ontogenetic stages. During nest founding in fungus-growing ants, foundresses of most genera use a garden platform to isolate the incipient fungal garden from the soil of the underground chamber. We studied nest founding in Acromyrmex octospinosus to test the hypotheses that the use of a platform (rootlets used to suspend the fungus garden): (i) reduces the likelihood that the garden will be contaminated by soil-borne microbial pathogens; (ii) results in more rapid growth of a young colony; and (iii) increases colony survival. We manipulated natural incipient nests to have gardens either in contact with or isolated from soil surrounding the chamber, and nests with and without foundresses present. We found a higher incidence of infection in gardens that were in contact with the chamber soil and without queens, compared with gardens isolated from the chamber soil with and without foundresses. The production of eggs, larvae and pupae, as well as leaf area harvested, were significantly different between nests with and without platforms, but there were no differences in the production of workers nor garden biomass. Likewise, there were no differences between treatments in colony survival rates over 8 weeks. Using smaller incipient gardens, however, gardens with and without platforms differed in survivorship rates after 24 hours. The results indicate that the use of a platform to cultivate an incipient fungal garden is an adaptation to reduce soil-borne diseases and increase colony performance. Received 28 July 2006; revised 15 November 2006; accepted 22 November 2006.     

Nest-founding in <Emphasis Type="Italic">Acromyrmex octospinosus</Emphasis> (Hymenoptera,Formicidae, Attini): demography and putative prophylactic behaviors

Summary Foundresses of the leaf-cutting ant Acromyrmex octospinosus in central Panamá forage for leaves as garden substrate (semi-claustral foundation). The fungal pellet and substrate usually are attached to rootlets, which are used as a platform for the garden. This arrangement keeps the garden suspended away from the earthen chamber of the underground nest during early colony growth, and we hypothesize that it serves to minimize contact between the garden and contaminants. A. octospinosus foundresses produce from 3 to 7 workers in 2.7 months after founding the nest, but workers do not forage for substrate at this time. Incipient nests died or were abandoned at a monthly rate of ca. 50%. We show that ants routinely clean their legs before manipulating the garden substrate. We also describe how foundresses use their fore-legs to rub the surface of the metapleural gland (MPG), and they then use typical grooming behaviors to pass the forelegs through the mouthparts, after which the ant then licks the garden substrate. Similarly, ants apparently use their mouths to transfer fecal droplets to their legs. We briefly discuss the functional significance of these grooming behaviors, and hypothesize that they are prophylactic behaviors that may help the foundress maintain a hygienic garden.     

Nest architecture of the leaf-cutting ant <Emphasis Type="Italic">Acromyrmex rugosus rugosus</Emphasis>

The prominent nests mounds of many ant species are one of the most obvious signs of their presence, yet the subterranean architecture of nests is often poorly known. The present work aimed to establish the external and internal structure of nests of a species of leaf-cutting ant, Acromyrmex rugosus rugosus, by either marking the interior of nests with talcum powder, or forming casts with cement. Twelve nests were excavated and surveyed, with eight being marked with talcum powder and four cast with cement. The external and internal structure of the nests was highly variable. The largest and smallest nests had mound areas of 9.89 m² and 0.01 m² respectively. The number of chambers found ranged from 1 to 26, with maximum dimensions of between 6 and 70 cm. Chambers were found close to the soil surface (6 cm) down to a maximum depth of 3.75 m. In addition to chambers containing fungus garden, some chambers were found to be empty, filled with soil or filled with waste, the first time this has been recorded in a species of Acromyrmex. The nests of A. rugosus rugosus appear to be unusually complex for the genus, containing a diversity of irregular chambers and tunnels. Received 21 December 2006; revised 30 May 2007; accepted 1 June 2007.     

The Role of Resource Density on Energy Allocation in the Neotropical Termite <Emphasis Type="Italic">Nasutitermes</Emphasis> aff. <Emphasis Type="Italic">coxipoensis</Emphasis> (Termitidae: Nasutitermitinae)

Organisms acquire energy from environment and must allocate it among different life traits (growth, maintenance and reproduction). Social insects must manage the energy allocation to various levels such as colony growth and caste functions. Here, we addressed the question of whether resource density affects the energy allocation to the number of individuals and caste functions as well as nest’s growth rate in the Neotropical termite Nasutitermes aff. coxipoensis (Homgren) (Termitidae: Nasutitermitinae). In a manipulative field experiment, colonies of N. aff. coxipoensis, with known volume, were maintained in plots with three different resource’s density (0.32, 0.64 and 1.92 baits/m²) over 3 months. After this period, the number of individuals as well as the caste identity and nest volume were measured. Surprisingly, our results showed that colonies reared in the extremes of resource’s density (0.32 and 1.92 baits/m²) produced a higher number of individuals compared with colonies reared with intermediate resource density (0. 64 baits/m²). The mean number of workers increased linearly with resource density; however, the average number of immature was higher in colonies reared with 0.32 baits/m² compared with colonies reared with 0.64 and 1.92 baits/m². No significant differences of resource density were observed in the mean number of soldiers, worker/soldier ratio as well as in the nest’s growth rate. In conclusion, the resource’s density seems to play an important role in determining the investment of energy in the number of individuals and caste in N. aff. coxipoensis colonies.     

Nesting biology of the arboreal fungus-growing ant <Emphasis Type="Italic">Cyphomyrmex cornutus</Emphasis> and behavioral interactions with the social-parasitic ant <Emphasis Type="Italic">Megalomyrmex mondabora</Emphasis>

We describe the extraordinary nesting habits of the fungus-growing ant Cyphomyrmex cornutus (Formicidae, Myrmicinae, Attini) and the natural history of Megalomyrmex mondabora (Formicidae, Myrmicinae, Solenopsidini), a social parasite that inhabits nests of C. cornutus and other small attine ants. The study was carried out at two sites on the Atlantic slope of Costa Rica. The C. cornutus nest is an oblong mass of accreted soil, attached to or suspended from low vegetation in wet forest understory. Less than a fourth of the nest volume has chambers and is inhabited by C. cornutus; the remainder is a semi-solid mass of accreted soil often housing a variety of arthropods, including other unspecialized commensal ant species. Five C. cornutus colonies examined were parasitized by M. mondabora. Colonies of M. mondabora inhabited chambers very near those of the host. In laboratory observations, M. mondabora and C. cornutus workers interacted with little aggression despite the consumption of C. cornutus larvae and fungi by M. mondabora. During most interactions, C. cornutus workers responded submissively, whereas M. mondabora appeared indifferent or nonresponsive. Megalomyrmex mondabora parasitizes several other attine species (Cyphomyrmex costatus, Cyphomyrmex salvini, and Apterostigma goniodes), and it appears therefore a relatively unspecialized social parasite with broad attine hostassociation. The size of M. mondabora workers vary with host species, suggesting M. mondabora sensu lato comprises either cryptic species or the host environment affects worker size. Received 14 September 2006; revised 1 February 2007; accepted 6 February 2007.     

Winter and spring ecology of <Emphasis Type="Italic">Anaphes nitens</Emphasis>, a solitary egg-parasitoid of the <Emphasis Type="Italic">Eucalyptus</Emphasis> snout-beetle <Emphasis Type="Italic">Gonipterus scutellatus</Emphasis>

We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments (n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber at 20°C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother’s diet and size affected development time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host. Handling editor: Drik Babendreier.     

Serum testosterone in females exposed to natural sour gas with respect to polymorphisms of <Emphasis Type="Italic">XRCC1</Emphasis>, <Emphasis Type="Italic">GSTM1</Emphasis>, and <Emphasis Type="Italic">GSTT1</Emphasis>

The present study was done to determine the modulation effect(s) of polymorphisms of XRCC1, GSTM1, and GSTT1 on concentration of serum testosterone in females exposed to natural sour gas. Also we examine whether chronic exposure to natural gas containing sulfur compounds act as natural selection force on XRCC1 polymorphisms. The present study was performed on 68 healthy unrelated female students living in polluted areas of MIS. Also for investigating the effect of natural selection on XRCC1 polymorphism, a study was performed on two groups of healthy individuals of MIS citizens. The first and second groups including 94 (age range 30–85 years) and 187 individuals (age range 5–20 years), respectively. First and second groups were born and were not born in contaminated areas of the MIS, respectively. There was no significant difference between genotypes of XRCC1 for concentration of serum testosterone. Although GSTT1-null genotype had higher level of serum testosterone in comparison with the present genotype (t = 2.392, df = 66, P = 0.023), a borderline difference between genotypes of GSTM1 for serum testosterone was observed (t = 1.928, df = 66, P = 0.058). Analysis of variance revealed significant difference between combination genotypes of GSTM1 and GSTT1 for serum testosterone (F = 4.167; df = 3, 64; P = 0.009). The Duncan post hoc test indicated that the combination genotype of “present GSTM1/null GSTT1” had significant higher level of testosterone. There is no evidence that XRCC1 polymorphisms have advantage/disadvantage when population exposed to natural sour gas. The polymorphisms of GSTM1 and GSTT1 modulate serum testosterone concentration in young females exposed to natural sour gas.     

Caste specialization in behavioral defenses against fungus garden parasites in <Emphasis Type="Italic">Acromyrmex octospinosus</Emphasis> leaf-cutting ants

Division of labor and caste specialization plays an important role in many aspects of social insect colony organization, including parasite defense. Within leaf-cutting ant colonies, worker caste specialization permeates colony tasks ranging from foraging, substrate incorporation, brood care, and chemical defenses via glandular secretions and mutualistic bacteria. Leaf-cutting ants rely on protecting a mutualistic fungus they grow for food from microfungi in the genus Escovopsis that parasitizes the ant–fungus relationship. Here, we examine whether Acromyrmex octospinosus leaf-cutter ant castes (minors and majors) display task specialization in two behavioral defenses against Escovopsis: fungus grooming (the removal of Escovopsis spores) and weeding (the removal of large pieces of Escovopsis-infected fungus garden). Using behavioral observations, we show that minors are the primary caste that performs fungus grooming, while weeding is almost exclusively performed by majors. In addition, using a sub-colony infection experimental setup, we show that at the early stages of infection, minors more efficiently remove Escovopsis spores from the fungus garden, thereby restricting Escovopsis spore germination and growth. At later stages of infection, after Escovopsis spore germination, we find that major workers are as efficient as minors in defending the fungus garden, likely due to the increased importance of weeding. Finally, we show, using SEM imaging, that the number of sensory structures is similar between minor and major workers. If these structures are invoked in recognition of the parasites, this finding suggests that both castes are able to sense Escovopsis. Our findings support that leaf-cutter ant behavioral defense tasks against Escovopsis are subject to caste specialization, likely facilitated by worker sizes being optimal for grooming and weeding by minors and majors, respectively, with important consequences for cultivar defense.     

Social parasitism of <Emphasis Type="Italic">Polistes dominulus</Emphasis> by <Emphasis Type="Italic">Polistes nimphus</Emphasis> (Hymenoptera,Vespidae)

Summary Interspecific facultative social parasitism is well known in ants and in bumble-bees, but it is rarer in wasps. This form of parasitism is traditionally considered to be an intermediate stage in the evolution of obligate interspecific parasitism, where the parasites are no longer able to nest alone. We report field and experimental observations of a newly discovered facultative parasitic relationship between two closely related free-living Polistes species: P. nimphus and P. dominulus. P. nimphus foundresses sometimes usurp the nests of the larger P. dominulus before worker emergence. The invading queen takes over the nest with abundant abdomen stroking on the nest surface and is accepted by workers if they emerge 6 or more days after usurpation. Morphometric comparisons show that the usurper species, though smaller than its victims, has morphological adaptations consisting of larger heads, mandibles and front femora relative to their body size that may give it an advantage during nest invasion. This strategy is likely to be taken only after the foundress loses her original nest because invading P. nimphus queens have lower reproductive success than they would have had on their own nest. Overall, we found that P. nimphus usurpers use strategies of invasion similar to those of two obligate parasites, suggesting that this may be an example of one of the pathways by which social parasitism evolved.Received 4 April 2003; revised 8 August 2003; accepted 14 September 2003.     

Application of a formulation of the nematophagous fungus <Emphasis Type="Italic">Duddingtonia</Emphasis><Emphasis Type="Italic">flagrans</Emphasis> in the control of cattle gastrointestinal nematodiosis

The viability of a formulation of Duddingtonia flagrans was assessed in the control of parasite gastrointestinal nematodes of cattle. Two groups (A and B) of eight crossbred Holstein × Zebu cattle, approximately one year old, were placed in Brachiaria decumbens pasture. Each animal in group B (treated) received orally 20 g sodium alginate pellets containing mycelial mass of the D. flagrans fungus, while the animals in the group A (control) received pellets without fungus for seven months, starting in March 2005. The egg per gram of feces counting the gastrointestinal nematodes showed a difference (P < 0.05) in the treated group in June, July and August, with reductions of 58% (June), 47% (July) and 51% (August) compared to the control group. The infective larvae recovered in the pastures collected up to 20 cm from distance of the fecal dung in group B differed (P < 0.01) from the larvae recovered in group A. At the end of the experimental period, the animals in group B presented a greater weight gain (P < 0.01) compared to the untreated group (A). The treatment of cattle with pellets containing the D. flagrans nematophagous fungus, at the dose and duration used was effective in controlling the infective larvae of gastrointestinal nematodes of cattle.     

Nest architecture of the ant <Emphasis Type="Italic">Formica pallidefulva</Emphasis>: structure,costs and rules of excavation

Summary The architecture of underground ant nests was studied in the ant Formica pallidefulva. These ants build shallow (30–45 cm deep) nests, which consist of more or less vertical shafts that bear chambers. Shafts are modular units of nest growth; nests are enlarged by adding more shafts or extending previously existing ones. The nests are top-heavy, their volume declining exponentially with depth. The total volume of the nest is strongly correlated with the number of worker occupying the nest (R² = 0.87). Some of the rules and templates used by workers for nest construction were determined: (a) chambers are formed in the direction of the tunnels leading up to them, (b) the amount of soil excavated per unit time increases with soil temperature and moisture content. The amount of time and energy required to construct a typical nest were approximated using digging ability parameters determined in the lab. We estimate that if a colony was to move twice a year, it would expend around 20% of its energy intake and at least 6% of its worker time on nest excavation.Received 16 December 2002; revised 10 July 2003; accepted 23 July 2003.     

Nest-moving by the polydomous ant <Emphasis Type="Italic">Cataglyphis iberica</Emphasis>

In this paper we analyze emigration from nests by the polydomous ant Cataglyphis iberica. Social carrying of workers of this species between different nests of the colony is frequent. In Bellaterra (Barcelona, NE Spain), we monitored field emigration of C. iberica by noting for each nest the migratory behavior of C. iberica workers and, when the nests were attacked by another ant species, Camponotus foreli, we noted the number of C. foreli workers involved in the attacks. Emigration of C. iberica from nests was highly variable. We suggest the main factor determining emigration by this species was attack by workers of C. foreli, so emigration from C. iberica nests was much faster when harassment by C. foreli increased. The system of multiple nests of C. iberica enables this species to abandon attacked nests and to reinstall their population in other nests of the same colony. This reduces risk to the colonies because the route between the different nests is well known by transporter workers.     

Biology of <Emphasis Type="Italic">Lasioglossum</Emphasis> (<Emphasis Type="Italic">L.</Emphasis>) <Emphasis Type="Italic">majus</Emphasis> (Hymenoptera: Halictidae), a largely solitary sweat bee with behavioural adaptations to communality

Within the bee family Halictidae there have been three origins of sociality. Although detection of origins and reversal from sociality requires phylogenetic studies, at a behavioural level a predisposition to sociality can be detected by analysis of intra-specific interactions. We studied aspects of nesting biology and behavioural interactions in Lasioglossum (Lasioglossum) majus, a poorly known halictine inhabiting temperate regions of Europe, which is suspected to be solitary. Nests were found to be largely used by one female, but some were shared by more than one individual. These few nests, whose entrances were very close to each other, were found to be connected underground. A few individuals were observed to enter in a nest where a female was waiting, behaving as a guard and allowing the incoming bee to enter the nest. By use of circle-tube experiments, the behavioural repertoire exhibited by females during encounters was assessed. Levels of withdrawal and cooperative events were comparable with those observed in other solitary nesting species, but aggressive events were very rare, as in several observed communal species. We conclude that L. (L.) majus females, despite general solitary nesting, possess behavioural components enabling them to adopt, probably in high nest-density areas, nest-sharing strategies. A similar kind of local social polymorphism has been observed in two other species of the subgenus Lasioglossum, but these are the first data available on a European species and the first record of subterranean connections among nests of halictid bees.     

Variants in <Emphasis Type="Italic">COMT</Emphasis> and <Emphasis Type="Italic">DBH</Emphasis> Influence on Response Inhibition Ability in Chinese Han Females

Catechol-O-methyltransferase (COMT) and dopamine-beta hydroxylase (DBH) are key enzymes to breakdown dopamine. Some previous studies have indicated that val158met in COMT and 19 bp insertion/deletion in 5′ flank of DBH are related to the performance of executive function. To further investigate the associations of the two genes with executive function, we performed a population-based study in a Chinese Han population. The results indicated that val158met in COMT and the 19 bp insertion/deletion of DBH were associated with the average reaction time of response inhibition in female group (P = 0.01, P = 0.03), respectively. Furthermore, there was a significant interaction of the two genes on the reaction time (P = 0.006). This present study suggests that not only do COMT and DBH influence independently on response inhibition in females, but also exert a significant interaction on response inhibition.     

Sexual reproduction of the brooding sponge <Emphasis Type="Italic">Rhopaloeides odorabile</Emphasis>

Sexual reproduction of Rhopaloeides odorabile, a common Great Barrier Reef sponge, was quantified using histological sections from samples collected over two reproductive seasons. Rhopaloeides odorabile is viviparous and gonochoristic with a male biased sex ratio (2.5:1). Commencement and cessation of gametogenesis coincides with rising and falling sea surface temperatures (≈24–29°C). Spermatogenesis occurs from October until January. Females initiate oogenesis in September with the asynchronous development of oocytes, embryos and larvae occurring within the brood chambers. A larval release period of 5–6 weeks occurs during January and February. The minimum size of reproductive individuals was 176 cm³ for females and 192 cm³ for males. The total reproductive output for both sexes shows a positive correlation with size. A relative reproductive output index quantified the maximum reproductive investment at approximately 1 and 3% of the total choanoderm for females and males, respectively, which represents a lower range of reproduction in comparison to other viviparous sponges. Low reproductive output in R. odorabile may be offset by an extended spawning period, alleviating the risk of releasing larvae in potentially adverse conditions via one synchronised spawning event and increasing overall larval survival.