Ovarian Dissection Research Articles

Rice planting systems, global warming and outbreaks of Nilaparvata lugens (Stål)

Brown Planthopper (BPH, Nilaparvata lugens (Stål)) is one of the most serious pests of rice in both temperate and tropical regions of East and South Asia and has become especially problematic over the past few years. In order to analyze the effect of the change of rice cropping system on the population dynamics of BPH, field surveys of the occurrence and distribution of BPH were performed and other relevant data, including light trap data and ovary dissection data were collected in nearly 40 Chinese counties encompassing six provinces (or municipalities), including Hainan, Guangxi, Anhui, Shanghai, Fujian and Guangdong from April to October in 2007.The mixed planting areas of single- and double-cropping rice in China include Hubei, South and Central Anhui, North Hunan, and North Jiangxi. In these areas, double-cropping rice has now been greatly reduced and single-cropping rice has been rapidly increasing since 1997. The surveys revealed that when the immigration peak of BPH occurred in June and July, the single-cropping rice was at the tillering to booting stage and fit for BPH, but early rice had already matured and most of late rice had not yet been transplanted. BPH immigrants from southern rice areas prefer to inhabit and breed in single-cropping rice paddies. Moreover, farming activities between early rice and late rice interrupted the continuous growth of BPH populations in double-cropping rice paddies. As a result, in comparison with data collected 30 years ago, the spatiotemporal dynamics and migration patterns of BPH have dramatically changed in the lower-middle reaches of the Yangtze River. In the mixed planting areas, due to their high suitability, the BPH population in single-cropping rice grew so quickly that it caused serious local damage and there was mass emigration of macropterous progeny to the Yangtze River Delta in late August and early September.Global warming may also affect BPH populations, where results suggest steadily warmer autumns have occurred from the 1990s on, with such conditions gradually the norm. The combination of 'cooler summer' and 'warmer autumn' are conditions known to promote outbreaks of BPH in the lower-middle reaches of the Yangtze River. Immigrant BPH arrivals in late August and September now cause serious damage to late-maturing mid-season rice and late rice in the lower-middle reaches of the Yangtze River.

Standing Laparoscopic Ovariectomy Technique with Intraabdominal Dissection for Removal of Large Pathologic Ovaries in Mares

To describe a standing laparoscopic ovariectomy technique with intraabdominal ovarian dissection inside a specimen retrieval bag for removal of large pathologic ovaries through small incisions. Case series. Mares (n=43) aged 2-21 years and weighing 380-680 kg. Unilateral laparoscopic ovariectomy was performed on 43 standing sedated mares. Ovaries were approached via 3 portal sites, 2 in the paralumbar fossa and a 3rd between the 17th and 18th ribs on the ipsilateral side. Ovaries were dissected free using either a LiNA Tripol-bipolar laparoscopic forceps or a Ligasure Vessel Sealing Device and removed by enlarging the proximal portal site ventrally using a grid technique. Use of a plastic specimen retrieval bag and cannula suction device facilitated intraabdominal dissection of very large ovaries into 2 or more pieces, before removal through small incisions. Regardless of size, all ovaries were removed successfully through small incisions (range, 5-10 cm), with no major complications and an excellent cosmetic result. All sport horses returned to previous levels of work or higher, with 93% of breeding mares successfully bred in the 1st season after surgery. Large pathologic ovaries can be easily and safely removed by standing laparoscopic ovariectomy on the mare. Standing laparoscopic ovariectomy combined with a small flank incision is a safe and highly effective technique for removal of large pathologic ovaries in the mare, negating the requirement for general anesthesia or large incisions.

Transmission des plasmodies humaines dans les villages de N'gatty et d’Allaba en milieu lagunaire de Côte d'Ivoire

The ecological and climatic variations in tropical areas of Africa make the transmission of malaria very heterogeneous. Several species of mosquitoes of the Anopheles genus transmit the disease. In Côte d'Ivoire, studies in the southern and northern forests have shown the involvement of Anopheles gambiae, An. funestus and An. nili in this transmission. This study was conducted in N'gatty and Allaba, two villages in a lagoon area of southern Côte d'Ivoire, in the district of Dabou. The district is located between 05 degrees 18 N and 04 degrees 27 W, about 40 kilometres from the economic capital of Côte d'Ivoire, and has a surface of 2257.8 km2. Two lagoon villages, N'gatty and Allaba, about a kilometre apart, were selected as sites for this research. The topography of N'gatty is rugged, with two important sides: a banana plantation on the west and the lagoon on the east, covered by aquatic plants (Pistia stratiotes, Acrosticum aureum, nympheacae and Eichhornia crassipes). This aquatic vegetation separates the last plots of the village from the lagoon. Mosquito populations were sampled from December 2007 through September 2008 by nighttime captures on volunteers three consecutive nights each month, inside six living rooms (4 in N'gatty and 2 in Allaba, a smaller village). The mosquitoes were captured when they landed on the volunteer's legs. There were two teams of catchers for each home; the first worked from 18:00 h to 24:00 and the second from 24:00 to 06:00. The ovaries and glands of An. gambiae were dissected. The physiological age of the females was determined by the appearance of the trachea on ovarian dissection. The sporozoites were sought by optic microscopy in cooled glands in a drop of physiological salt solution. During the 10 months of this study, 21 137 mosquitoes were caught in N'gatty and 7163 in Allaba. An. gambiae species accounted for less than 2% of the mosquito fauna in the two villages. Overall, the average bite rate was 203.24 bites per man per night (b/m/n) in N'gatty and 137.75 in Allaba. The average number of An. gambiae bites was 4.04 b/m/n in N'gatty and 2 b/m/n in Allaba. Annually, the average An. gambiae bites totalled 1474.6 bites per man per year (b/m/y) in N'gatty and 730 in Allaba. No An. funestus mosquito was caught in Allaba, and its average number of bites per man per year in N'gatty was only 3.65. No infected glands (n = 420 dissected) were found in N'gatty throughout the investigation. The mean sporozoite rate in Allaba was only 0.285% (n = 104). The mean entomological inoculation rate (EIR) was estimated at 0.017 infecting bites per man and per night (ib/m/n) in N'Gatty and 6.2 in Allaba. This weak entomological inoculation rate leads us to consider continuing the research for infection of An. gambiae by ELISA techniques. In conclusion, malaria transmission by An. gambiae in this area is very low.

Mullerian Adenosarcoma of the Cervix in a 10-Year-Old Girl: Case Report and Review of the Literature

Müllerian adenosarcoma is a rare neoplasm usually found in postmenopausal women. It usually presents as a polypoid mass within the endometrium. It is a biphasic tumor, composed of a benign epithelial component and a malignant stromal component. To date, this neoplasm has been reported in only 16 adolescent girls. We present a case of a 10-year-old girl who was diagnosed with müllerian adenosarcoma arising from the endocervix, the youngest female ever reported. Case Report A 10-year-old previously healthy girl presented to the Emergency Department at the Children's Hospital of Eastern Ontario with a painless mass protruding from her vagina. She had experienced mild vaginal bleeding for two weeks prior to her presentation. On physical examination, her vital signs were stable, and pubertal development was Tanner III breast and Tanner II pubic development. Rectoabdominal examination was negative. Two polypoid lesions were seen protruding past the hymenal ring and were removed in the emergency department. On gross examination, they were a dark tan color and had a fleshy appearance with a gelatinous consistency. They measured 5.5 × 1.5 × 1.0 cm and 3.5 × 1.5 × 1.5 cm. The final pathology revealed müllerian adenosarcoma, favoring an endocervical origin. Further investigations, including an abdominal/pelvic ultrasound and MRI and chest radiography, were negative. The patient subsequently underwent examination under anesthesia, vaginoscopy, hysteroscopy, polypectomy, and dilatation and curettage. The vagina appeared normal. At the level of the cervix, there were 3 polypoid gelatinous structures arising from the endocervix and extruding past the exocervix. They measured 0.8 × 0.5 × 0.2 cm up to 1.1 × 0.7 × 0.5 cm. The lesions were removed. Hysteroscopic inspection of the uterine cavity did not find any abnormalities. An endometrial curettage was performed. Pathology confirmed a diagnosis of müllerian adenosarcoma originating from the endocervix. Uterine curettings were negative for malignancy. After a thorough evaluation of the available literature, review with the Regional Tumor Board and extensive discussions with the family, a decision was made to perform a radical hysterectomy, bilateral salpingectomy, bilateral pelvic lymph node dissection, upper vaginectomy and preservation of ovaries. The procedure was uncomplicated. Clinically, there was no evidence of residual disease. The final pathology was negative for malignancy. Conclusion Müllerian adenosarcoma of the endocervix is a very rare pediatric tumor. Due to the rarity of this tumor in this age group, optimal therapy is uncertain. Most experts recommend hysterectomy. The review of literature reveals a high recurrence rate following conservative surgical management. Chemotherapy and radiation have not been used in the absence of extensive pelvic and/or residual disease. Poor prognostic factors include depth of invasion, sarcomatous overgrowth and high-grade malignant features in the stromal component. If recurrence occurs, it tends to be local and following prior conservative treatments such as cone biopsy or trachelectomy. Recurrences may occur late and thus long term follow-up of these patients is recommended.

Mitigation of egg limitation in parasitoids: immediate hormonal response and enhanced oogenesis after host use

Synovigenic insects (i.e., insects emerging with few ripe eggs and maturing more eggs during the course of their lifetime) may suffer from transient egg limitation due to the stochastic nature of encounters with patchy hosts and the low availability of ripe eggs at any given time point. Egg limitation also affects the stability of host-parasitoid models. Thus, quantification of the behavioral decisions influencing egg maturation, identification of the underlying physiological mechanisms, and determination of the rate of egg maturation are highly relevant to both parasitoid behavioral ecology and host-parasitoid population dynamics. The aim of this study was to identify, in a highly controlled setting, the physiological processes responsible for egg manufacture after varying host use by a synovigenic parasitoid. We quantified the time course of the reproductive hormonal response and subsequent egg production in the host feeding bruchid parasitoid, Eupelmus vuilleti (Hymenoptera: Eupelmidae) for three treatments: (1) host examination without further host use, (2) host feeding, and (3) host feeding followed by oviposition. We carried out continuous behavioral observations with single hosts, enzyme immunoassays for quantifying ecdysteroids, and ovary dissection. Ecdysone levels increased within two minutes of contact with a host, the fastest hormonal response reported for any insect. Even simple contact with a host, without further host use, triggered an increase in hormone levels, leading to the maturation of a single egg, using body reserves only. Feeding on the host caused a much larger increase in ecdysone levels and was followed by a marked increase in oogenesis. Oviposition had a weak effect on hormone levels, but increased oogenesis. We discuss the mechanisms responsible for these rapid responses, the source of ecdysteroids, and the implications of our results for the population dynamics of host-parasitoid systems and the behavioral ecology of synovigenic species.

Population genetic structure, worker reproduction and thelytokous parthenogenesis in the desert ant Cataglyphis sabulosa

In social Hymenoptera, within-colony relatedness is usually high due to the haplodiploid sex-determining system. However, factors such as the presence of multiple reproductive queens (polygyny), multiple queen matings (polyandry) or worker reproduction result in decreased relatedness among workers and the brood they rear, and consequently dilute their inclusive fitness benefits from helping. Here, we investigated population genetic structure, mating system, worker reproduction and parthenogenesis in the desert ant Cataglyphis sabulosa. Analysis of worker genotypes showed that colonies are headed by a single queen, mated with 1-5 males. The inbreeding coefficient within colonies and the levels of relatedness between the queens and their mates were positive, indicating that mating occurs between related individuals. Moreover, the mates of a queen are on average related and contribute equally to worker production. Our analyses also indicate that colonies are genetically differentiated and form a population exhibiting no isolation-by-distance pattern, consistent with the independent foundation of new colonies (that is, without the help of workers). Finally, both ovarian dissections and genetic data on the parentage of males show that workers do not reproduce in queenright colonies; however, they lay both haploid (arrhenotokous males) and diploid (thelytokous females) eggs in queenless colonies. In contrast to the congeneric species C. cursor, where new queens are produced by thelytokous parthenogenesis, female sexuals of C. sabulosa result from classical sexual reproduction.

Sociality in the phylogenetically basal allodapine bee genus Macrogalea (Apidae: Xylocopinae): implications for social evolution in the tribe Allodapini

Recent phylogenetic studies based on DNA sequence data indicate that the tropical African bee genus Macrogalea is the sister group to the remaining extant allodapine fauna, whereas previously it was thought to be a distal group. This leads to some fundamental changes in our understanding of social evolution in the allodapines. Earlier studies suggested that Macrogalea showed only weak forms of social behaviour and these were not well characterized. However, large samples of Macrogalea zanzibarica presented here show that this species exhibits marked social behaviour. Nearly half of nests collected contained two or more adult females, with up to 10 females per nest. Brood are reared progressively and brood ages within colonies are staggered, giving rise to colonies with very mixed age structures and therefore frequent opportunities for alloparental care. Ovarian dissections indicate non-simple forms of reproductive partitioning within colonies and most multi-female colonies show evidence that more than one female has contributed to egg production, though reproductive episodes among colony members are frequently asynchronous. Some females show signs of much higher wing wear than their nestmates, but always show signs of previous reproduction. Reproductive division of labour appears to be temporally marked, ovarian differentiation among nestmates is linked to relative body size, but permanent worker-like or queen-like castes appear to be absent. This is similar to the communal, continuously brooded and multivoltine behaviour of some tropical halictine species and may be due to the aseasonal nature of brood development in tropical regions. Patterns of per capita brood production indicate large benefits to multi-female nest occupancy, and sex allocation is strongly female biased. These findings strongly suggest that the capacity for complex social interactions and alloparental care is an ancestral trait for all of the extant allodapine lineages. Therefore comparisons among extant allodapines are unlikely to throw light on the initial origin of social behaviour, though they may uncover origins of true caste behaviour and reversals to solitary nesting. Sex ratios in Macrogalea and most other allodapine genera, spanning a broad phylogenetic and ecological range, suggest that one or more allodapine traits have provided persistent selection for female-biased sex allocation.

Seasonal abundance and reproductive output of the dung fliesNeomyia cornicinaandN. viridescens(Diptera: Muscidae)

The seasonal abundance and reproductive output of two common, but little studied, dung-breeding flies, Neomyia cornicina and N. viridescens, were examined in artificial cow pats in pastures in southwest England in 2001 and 2004. In 2001, the numbers of both Neomyia species increased slowly over summer to show a sharp seasonal peak in late August and early September. There was no significant effect of mean temperature, mean relative humidity or dung water content on abundance or seasonally de-trended abundance. High levels of aggregation were seen between pats and, when present, greater numbers of N. cornicina emerged than N. viridescens. Neomyia cornicina was present in 13% of 240 artificial standardized pats put out in 2001, at a median of 19 adults per colonized pat; N. viridescens was present in 8% of artificial pats at a median of three adults per colonized pat. In 2004, N. cornicina emerged from 46% of the 94 artificial pats put out at a median of three adults per colonized pat, while N. viridescens emerged from only 12% of pats at a median of one adult per colonized pat. Flies were also collected in 2004, using sticky-traps and hand nets. Again, free-flying N. cornicina appeared to be more abundant in the field than N. viridescens; 162 N. cornicina were caught compared to 44 N. viridescens over the same sampling period. The size of each adult female was recorded and ovarian dissection was used to determine the numbers of eggs matured. Female N. viridescens were significantly larger than the N. cornicina and matured significantly higher numbers of eggs. Gravid N. viridescens matured a mean of 37.1 (+/-16.9) eggs, whereas gravid N. cornicina matured a mean of 28.8 (+/-13.2) eggs. The reasons why the larger, more fecund, N. viridescens adults are less abundant in the field or emerging from pats than N. cornicina are unknown. Further work is required to identify the nature and cause of the mortality experienced by the larvae of these species and the ecological differences and functional specialisation which allows co-existence to be maintained.

Determinants of Anion-Proton Coupling in Mammalian Endosomal CLC Proteins

Many proteins of the CLC gene family are Cl(-) channels, whereas others, like the bacterial ecClC-1 or mammalian ClC-4 and -5, mediate Cl(-)/H(+) exchange. Mutating a "gating glutamate" (Glu-224 in ClC-4 and Glu-211 in ClC-5) converted these exchangers into anion conductances, as did the neutralization of another, intracellular "proton glutamate" in ecClC-1. We show here that neutralizing the proton glutamate of ClC-4 (Glu-281) and ClC-5 (Glu-268), but not replacing it with aspartate, histidine, or tyrosine, rather abolished Cl(-) and H(+) transport. Surface expression was unchanged by these mutations. Uncoupled Cl(-) transport could be restored in the ClC-4(E281A) and ClC-5(E268A) proton glutamate mutations by additionally neutralizing the gating glutamates, suggesting that wild type proteins transport anions only when protons are supplied through a cytoplasmic H(+) donor. Each monomeric unit of the dimeric protein was found to be able to carry out Cl(-)/H(+) exchange independently from the transport activity of the neighboring subunit. NO(3)(-) or SCN(-) transport was partially uncoupled from H(+) countertransport but still depended on the proton glutamate. Inserting proton glutamates into CLC channels altered their gating but failed to convert them into Cl(-)/H(+) exchangers. Noise analysis indicated that ClC-5 switches between silent and transporting states with an apparent unitary conductance of 0.5 picosiemens. Our results are consistent with the idea that Cl(-)/H(+) exchange of the endosomal ClC-4 and -5 proteins relies on proton delivery from an intracellular titratable residue at position 268 (numbering of ClC-5) and that the strong rectification of currents arises from the voltage-dependent proton transfer from Glu-268 to Glu-211.

Permanent loss of wings in queens of the ant Odontomachus coquereli from Madagascar

Winged queens are the most common reproductives in ants. They are morphologically specialized for independent colony foundation, with wings for long-range dispersal and metabolic reserves to raise the first brood. However independent foundation can sometimes be selected against and replaced by fission, featuring short-range dispersal on the ground and reproductives that are dependent on the wingless workers for all non-reproductive tasks. We investigated the evolutionary consequences of this transition on the morphology of the reproductives by collecting 30 colonies of Odontomachus coquereli from Madagascar, the only species in the genus where winged queens have never been found. Data about colony demography, morphometry, allometry and ovarian dissections showed that the winged queen caste has been replaced by a wingless reproductive caste with distinct body proportions relative to the workers or to congeneric winged queens. The 17 reproductives that we measured exhibited little size variability. A single wingless reproductive was found in each colony, corresponding to ‘ergatoids’ in literature. Several facts suggest that colonies reproduce by fission, notably the relatively constant colony size (19±11 workers). The developmental origins of wingless reproductive phenotypes need investigation; little genetic change may be involved, as seen when Odontomachus larvae are parasitized by nematodes. The sole function of wingless reproductives in O. coquereli is reproduction, and they contrast with multi-purpose wingless reproductives found in other ants, where numerous intermorphs occur in each colony and contribute to sterile tasks.

The function of multiple mating in oviposition and egg maturation in the seed beetle Callosobruchus maculatus

Abstract To comprehend the significance of multiple mating in female Callosobruchus maculatus, the material‐benefits hypothesis is tested, as well as the potential function and mechanism of additional mating for females. The results show that longevity and lifetime fecundity are significantly higher in doubly‐mated females, whereas females subject to an interrupted second copulation (which transfers no ejaculate) show resemblance with singly‐mated females in lifetime fecundity and daily fecundity, supporting the material‐benefits hypothesis. Female lifetime fecundity increases with ejaculate size in doubly‐, but not singly‐mated females. Doubly‐mated females exhibit an immediate increase in fecundity on the day of remating. Moreover, dissection of ovaries after remating shows that the number of unlaid eggs is lower in doubly‐mated females in comparison with singly‐mated females, whereas the total number of unlaid and laid eggs shows no significant difference. This suggests that the second mating increases the oviposition rate, but not the egg maturation rate in female C. maculatus. Thus, ejaculate serves as a stimulus for oviposition, at least on the remating day. However, because doubly‐mated females lay more eggs in total than singly‐mated females, doubly‐mated females appear to mature more eggs than the singly‐mated counterparts. This is attributed to the ‘indirect‐driven’ hypothesis, which states that the reduction in the number of mature eggs in the oviducts brought about by oviposition stimulates the maturation of oocytes in ovarioles to replenish the number of mature eggs.

Paridade de Ochlerotatus scapularis em condições de laboratório e campo

To identify the parity status of Ochlerotatus scapularis females in laboratory and field conditions. Field collections were carried out fortnightly using a hand-held aspirator in Vale do Ribeira, Southeastern Brazil, from April 2003 to March 2004. In laboratory, 100 Ochlerotatus scapularis F1 females were obtained and followed up individually, reporting the number of blood meals, the length of gonotrophic cycle, survival and number of eggs laid. The parity status and ovarian development were observed through ovarian dissection of 90 field females for each collection and all females reared in laboratory. The parity status diagnoses of the 100 females reared in laboratory and dissected agreed with 55% of the oviposition data, and it was underestimated in 37% and overestimated in 2%. Also in the laboratory, 106 gonotrophic cycles were completed, around 55% of females needed more than one blood meal before laying eggs. In laboratory conditions the species survival was 26 days. A total of 1,180 field females of Ochlerotatus scapularis were dissected: 418 (35.4%) nulliparous, 655 (55.5%) uniparous, 46 (3.9%) biparous and 61 (5.2%) could not be evaluated. Ninety field females were found in Christophers and Mer's phase III-V. The gonotrophic discordance hypothesis could be confirmed based on field and laboratory observations of Ochlerotarus scapularis females.

Self-restraint and sterility in workers of Acromyrmex and Atta leafcutter ants

Queens of leafcutter ants (Acromyrmex and Atta) are highly multiply mated, resulting in a potential queenworker and worker-worker conflict over who should produce the males in the colony. We studied whether this conflict is expressed, by determining the amount of reproductive egg-laying by workers in queenright colonies of Acromyrmex echinatior, Acromyrmex octospinosus, Atta cephalotes, and Atta sexdens through ovary dissections. Worker sons are absent or rare in queenright Acromyrmex colonies, but can be produced in orphaned colonies. In Atta, most workers have rudimentary ovaries that never produce eggs, but a few (mostly small and medium workers that form a retinue around the queen) lay many trophic eggs for consumption by the queen. These eggs are large, flaccid, and lacking in yolk compared to queen-laid eggs, and appear to be always inviable. In Acromyrmex, many workers (especially young large workers) lay eggs that are similar in size to queen-laid eggs, but mostly with a reduced amount of yolk. Trophic eggs appear to be an important source of food for larvae in Acromyrmex (especially in Ac. echinatior), but not in Atta. Five (0.8) of 616 dissected Ac. echinatior workers but no Ac. octospinosus workers (n = 552), had ready-to-lay reproductive eggs. Old workers in all four species are incapable of laying eggs due to ovary resorption. We conclude that Atta workers are sterile, while Acromyrmex workers display reproductive self-restraint, possibly representing an earlier stage in the evolution towards worker sterility. Worker selfrestraint in Acromyrmex may be maintained by a queen or worker policing mechanism, but individual cost-benefit explanations may also apply.

Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata

Abstract. 1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north‐western Europe.2. Populations of marked flies in six, 1 m3, outdoor field cages and unmarked wild flies at two farms in south‐west England were studied simultaneously between May and September 1998.3. In the field, wild female L. sericata were caught and aged using a combination of wing‐fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% (± 0.037) and 2.09% (± 0.044) per day‐degree and mean life expectancy of 51.5 and 47.9 day‐degrees above a threshold of 11 °C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively.4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day‐degree (± 3.49 × 10−4%) and the mean life expectancy was 123.1 day‐degrees above a threshold of 11 °C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best‐fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition.5. The differences between the field and cage populations highlight the caution required when extrapolating life‐history parameters from artificial to natural habitats.

Gamergates in the Australian ant subfamily Myrmeciinae.

Ant workers can mate and reproduce in a few hundreds of species belonging to the phylogenetically basal poneromorph subfamilies ( sensu Bolton 2003). We report the first occurrence of gamergates (i.e. mated reproductive workers) in a myrmeciomorph subfamily. In a colony of Myrmecia pyriformis that was collected without a queen, workers continued to be produced over a period of 3 years in the laboratory. Behavioural observations and ovarian dissections indicated that three workers were mated and produced the diploid offspring. The Myrmeciinae are thus another taxon in which the selective benefits of sexual reproduction by workers can be investigated.

More Eggs the Better: Egg Formation in Captive Barn Owls (Tyto Alba)

Abstract We studied rapid yolk deposition (RYD) in Barn Owls (Tyto alba) on the basis of the analysis of 26 eggs laid by “dye-dosed” captive female Barn Owls in five different broods. Pictures of yolks were examined to assess daily rates of yolk deposition. We used those data in combination with data from the dissection of ovaries of another five breeding females. We found that the total duration between initiation of RYD and laying of the corresponding egg was only 13.6 days, with an interval between yolk completion and oviposition of 2.4 days. The total number of follicles that may have given eggs was found to be 25. That high number of follicles and the short RYD period explain the particularly high reproductive potential of this nocturnal raptor species.

MORE EGGS THE BETTER: EGG FORMATION IN CAPTIVE BARN OWLS (TYTO ALBA)

Abstract We studied rapid yolk deposition (RYD) in Barn Owls (Tyto alba) on the basis of the analysis of 26 eggs laid by “dye-dosed” captive female Barn Owls in five different broods. Pictures of yolks were examined to assess daily rates of yolk deposition. We used those data in combination with data from the dissection of ovaries of another five breeding females. We found that the total duration between initiation of RYD and laying of the corresponding egg was only 13.6 days, with an interval between yolk completion and oviposition of 2.4 days. The total number of follicles that may have given eggs was found to be 25. That high number of follicles and the short RYD period explain the particularly high reproductive potential of this nocturnal raptor species.

The evolution of soldier reproduction in social thrips

We estimated the degree of reproductive differentiation between foundresses and soldiers in multiple populations of five species of haplodiploid Australian gall-forming thrips using microsatellite data, ovarian dissections, and census data. Microsatellite-based species estimates of average per capita reproductive output of soldiers relative to the foundresses ranged from 0.005 to 0.64, and dissection and census-based estimates ranged from 0.17 to 1.1. Mapping of these estimates onto a phylogeny showed that levels of soldier reproduction were apparently higher in three basal lineages than in two more derived lineages. We infer from this phylogenetic pattern that soldier morphology and behavior of thrips evolved in the presence of substantial levels of soldier reproduction. This pattern of evolutionary change is similar to that proposed for the origin of soldiers in aphids and termites, but it differs from the scenario proposed for the origin of workers in Hymenoptera, within which helping and strong reproductive division of labor apparently evolved before morphological differentiation. We suggest that this difference in evolutionary routes to eusociality between taxa with soldiers and taxa with foraging workers was driven by a weaker trade-off between helping and reproducing, and a greater ability of the helpers to withstand reproductive domination, in taxa with soldiers. This is the first study to analyze the social-evolutionary trajectories of reproductive, behavioral, and morphological differentiation in the context of a species-level phylogeny. Key words: castes, inbreeding, microsatellites, soldiers, thrips. [Behav Ecol 13:519–525 (2002)]

Phenological Synchrony ofEustenopus villosus(Coleoptera: Curculionidae) withCentaurea solstitialisin Idaho

The phenological synchrony of Eustenopus villosus (Boheman) with its host, yellow starthistle, Centaurea solstitialis L. (Asteraceae: Cardueae), was studied in Idaho in 1995 and 1996. Field plots were observed for adult weevil activity periodically throughout the growing season, and yellow starthistle capitula were examined for adult feeding damage, oviposition damage, and larval development. At the study site, weevil phenology was well synchronized with C. solstitialis. Immature capitula, fed upon by adults, were abundant when E. villosus began to emerge in late May. During both years, the number of weevils and capitula increased throughout June. Adult females fed on capitula for about 2 wk. Weevil ovary dissections revealed that ovaries were mature after a 2-wk period of feeding. The development of mature capitula during late July corresponded to the initiation of oviposition. Eustenopus villosus, unique among the phytophages introduced for C. solstitialis biological control, attacks four plant stages resulting in observable impact to buds. Damaged buds either died or became distorted. Weevil feeding damage on young and mature capitula may make this insect a highly effective control agent.

Convergent evolution of worker policing by egg eating in the honeybee and common wasp.

Mutual policing, where group members suppress each others' reproduction, is hypothesized to be important in the origin and stabilization of biological complexity. Mutual policing among workers in social insects can reduce within-colony conflict. However, there are few examples. We tested for worker policing in the common wasp Vespula vulgaris. Workers rapidly removed worker-laid eggs but left most queen-laid eggs (four out of 120 worker eggs versus 106 out of 120 queen eggs remained after 1h). Ovary dissection (1150 workers from six colonies) revealed that a small but significant number of workers have active ovaries (4%) equivalent to approximately five to 25 workers per colony. Consistent with effective policing of worker reproduction, microsatellite analysis of males (270 individuals from nine colonies) detected no workers' sons. Worker policing by egg eating has convergently evolved in the common wasp and the honeybee suggesting that worker policing may have broad significance in social evolution. Unlike the honeybee, relatedness patterns in V. vulgaris do not explain selection for policing. Genetic analysis (340 workers in 17 nests) revealed that workers are equally related to the queen's and other workers' sons (worker-worker relatedness was 0.51 +/- 0.04, 95% confidence interval). Worker policing in V. vulgaris may be selected due to the colony-level benefit of conflict suppression.