@article{booth_brent_calleri_rosengaus_traniello_vargo_2012, title={Population genetic structure and colony breeding system in dampwood termites (Zootermopsis angusticollis and Z. nevadensis nuttingi)}, volume={59}, ISSN={["1420-9098"]}, DOI={10.1007/s00040-011-0198-2}, number={1}, journal={INSECTES SOCIAUX}, author={Booth, W. and Brent, C. S. and Calleri, D. V. and Rosengaus, R. B. and Traniello, J. F. A. and Vargo, E. L.}, year={2012}, month={Feb}, pages={127–137} } @article{menten_fournier_brent_passera_vargo_aron_2005, title={Dual mechanism of queen influence over sex ratio in the ant Pheidole pallidula}, volume={58}, ISSN={["1432-0762"]}, DOI={10.1007/s00265-005-0964-0}, abstractNote={Social Hymenoptera are general models for the study of parent-offspring conflict over sex ratio, because 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 specialization 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 specialization 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 development 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.}, number={6}, journal={BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY}, author={Menten, L and Fournier, D and Brent, C and Passera, L and Vargo, EL and Aron, S}, year={2005}, month={Oct}, pages={527–533} } @article{brent_schal_vargo_2005, title={Endocrine changes in maturing primary queens of Zootermopsis angusticollis}, volume={51}, ISSN={["0022-1910"]}, DOI={10.1016/j.jinsphys.2005.06.009}, abstractNote={Termite queens are highly specialized for reproduction, but little is known about the endocrine mechanisms regulating this ability. We studied changes in the endocrinology and ovarian maturation in primary reproductive females of the dampwood termite Zootermopsis angusticollis following their release from inhibitory stimuli produced by mature queens. Winged alates were removed from their natal nest, manually dewinged, then paired in an isolated nest with a reproductive male. Development was tracked by monitoring ovarian development, in vitro rates of juvenile hormone (JH) production by corpora allata, and hemolymph titers of JH and ecdysteroids. The production rate and titer of JH were positively correlated with each other but negatively correlated with ecdysteroid titer. Four days after disinhibition, JH release and titer decreased while ecdysteroid titer increased. The new levels persisted until day 30, after which JH increased and ecdysteroids decreased. Fully mature queens had the highest rates of JH production, the lowest ecdysteroid titers, and the greatest number of functional ovarioles. The results support the hypothesis that JH plays a dual role in termite queens depending on their stage of development; an elevated JH titer in immature alates may maintain reproductive inhibition, but an elevated JH titer in mature queens may stimulate ovarian activity. The decline in JH production and the elevation in ecdysteroid titer correspond to a period of physiological reorganization and activation. The specific function of ecdysteroids is unknown but they may help to modulate the activity of the corpora allata.}, number={11}, journal={JOURNAL OF INSECT PHYSIOLOGY}, author={Brent, CS and Schal, C and Vargo, EL}, year={2005}, month={Nov}, pages={1200–1209} } @article{brent_vargo_2003, title={Changes in juvenile hormone biosynthetic rate and whole body content in maturing virgin queens of Solenopsis invicta}, volume={49}, ISSN={["1879-1611"]}, DOI={10.1016/S0022-1910(03)00166-5}, abstractNote={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.}, number={10}, journal={JOURNAL OF INSECT PHYSIOLOGY}, author={Brent, CS and Vargo, EL}, year={2003}, month={Oct}, pages={967–974} } @article{brent_traniello_2001, title={Influence of sex-specific stimuli on ovarian maturation in primary and secondary reproductives of the dampwood termite Zootermopsis angusticollis}, volume={26}, ISSN={["1365-3032"]}, DOI={10.1046/j.0307-6962.2001.00243.x}, abstractNote={Abstract. It was hypothesized that female primary and secondary reproductives of the termite Zootermopsis angusticollis Hagen require sex‐specific stimuli from a reproductive male to trigger ovarian maturation. To test this hypothesis, experimental laboratory colonies were established that contained female primary or secondary reproductives nesting: alone; with a male; with a female; and with three third‐ to fourth‐instar larvae. Following colony initiation, we measured changes in body mass, ovariole number and fecundity over 60 days. Results indicate that the reproductive maturation of female primaries was promoted by contact with a male but inhibited by the presence of another female. Secondary females were not affected by the presence of another reproductive, regardless of sex, but the development of reproductive competency of primary females appeared to depend on male‐specific stimulation. Reliance on male–female interaction to induce female reproductive development may ensure that the resources of newly dealate females are not wasted on producing larvae that would have a poor chance of surviving in the absence of a male. By contrast, secondary females maturing within established colonies are likely to have a mate and immediate assistance with non‐reproductive tasks, and therefore do not delay ovarian maturation and reproduction until they perceive male‐specific stimuli. These results demonstrate that male‐specific stimuli affect only the reproductive development of primary females, and suggest that the degree to which primary and secondary females depend on mate assistance may have shaped their physiological responses to the presence of a reproductive male.}, number={3}, journal={PHYSIOLOGICAL ENTOMOLOGY}, author={Brent, CS and Traniello, JFA}, year={2001}, month={Sep}, pages={239–247} } @article{brent_traniello_2001, title={Social influence of larvae on ovarian maturation in primary and secondary reproductives of the dampwood termite Zootermopsis angusticollis}, volume={26}, ISSN={["1365-3032"]}, DOI={10.1046/j.1365-3032.2001.00221.x}, abstractNote={We tested the effect of larvae on the reproductive maturation and fecundity of female primary and secondary reproductives of the termite Zootermopsis angusticollis Hagen (Isoptera; Termopsidae) by varying the number of third- to fourth-instar larvae nesting with heterosexually paired reproductives. Primary females had higher fecundities and oviposited sooner when nesting with larvae than females lacking larvae, but gained less body mass and had fewer functional ovarioles per ovary. Secondary reproductives nesting with larvae also had higher fecundities and oviposited sooner, but unlike primaries, they gained more body mass and had more functional ovarioles when larvae were present. The specific response of both primary and secondary females varied according to the number of larvae present. These results suggest that larvae can enhance the fecundity of primary and secondary females. Larvae may increase the energetic reserves of reproductives by performing colony labour, reducing pathogen load and providing trophallactic secretions. Trophallaxis with larvae may significantly enhance endogenous nitrogen, which is a limiting nutrient for termites. Primary females, which normally need to produce a first brood quickly to initiate a new colony, may expend limited nutritional resources on oogenesis rather than producing additional ovarioles. Primaries may also store fewer energetic reserves for long-term brood care, and therefore gained less mass when larvae were present to attend to non-reproductive tasks. Secondary females may exhibit a greater positive response to larvae than primaries because they begin reproductive life with fewer stored resources and thus their development and fecundity are more dependent on assistance from larvae. Both primary and secondary reproductives may become more dependent on the contributions of larvae as their rate of egg production increases with subsequent bouts of oviposition.}, number={1}, journal={PHYSIOLOGICAL ENTOMOLOGY}, author={Brent, CS and Traniello, JFA}, year={2001}, month={Mar}, pages={78–85} } @article{brent_traniello_2001, title={Social regulation of testicular development in primary and secondary males of the dampwood termite Zootermopsis angusticollis Hagen}, volume={48}, number={4}, journal={Insectes Sociaux}, author={Brent, C. S. and Traniello, J. F. A.}, year={2001}, pages={384–391} }