Gender Specific Brood Cells in the Solitary Bee Colletes halophilus (Hymenoptera; Colletidae)

We studied the reproductive behaviour of the solitary bee Colletes halophilus based on the variation in cell size, larval food amount and larval sex in relation to the sexual size dimorphism in this bee. Brood cells with female larvae are larger and contain more larval food than cells with males. Occasionally males are reared in female-sized cells. We conclude that a female C. halophilus in principal anticipates the sex of her offspring at the moment brood cell construction is started. Additionally a female is able to ‘change her mind’ about the sex of her offspring during a single brood cell cycle. We present a model that can predict the sex of the larvae in an early stage of development

Prediction of social structure and genetic relatedness in colonies of the facultative polygynous stingless bee Melipona bicolor (Hymenoptera, Apidae)

Stingless bee colonies typically consist of one single-mated mother queen and her worker offspring. The stingless bee Melipona bicolor (Hymenoptera: Apidae) shows facultative polygyny, which makes this species particularly suitable for testing theoretical expectations concerning social behavior. In this study, we investigated the social structure and genetic relatedness among workers from eight natural and six manipulated colonies of M. bicolor over a period of one year. The populations of M. bicolor contained monogynous and polygynous colonies. The estimated genetic relatedness among workers from monogynous and polygynous colonies was 0.75 ± 0.12 and 0.53 ± 0.16 (mean ± SEM), respectively. Although the parental genotypes had significant effects on genetic relatedness in monogynous and polygynous colonies, polygyny markedly decreased the relatedness among nestmate workers. Our findings also demonstrate that polygyny in M. bicolor may arise from the adoption of related or unrelated queens

Evaluation of Continuous Tumor-Size-Based End Points as Surrogates for Overall Survival in Randomized Clinical Trials in Metastatic Colorectal Cancer

IMPORTANCE: Tumor measurements can be used to estimate time to nadir and depth of nadir as potential surrogates for overall survival (OS). OBJECTIVE: To assess time to nadir and depth of nadir as surrogates for OS in metastatic colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS: Pooled analysis of 20 randomized clinical trials within the Aide et Recherche en Cancerologie Digestive database, which contains academic and industry-sponsored trials, was conducted. Three sets of comparisons were performed: chemotherapy alone, antiangiogenic agents, and anti–epidermal growth factor receptor agents in first-line treatment for patients with metastatic colorectal cancer. MAIN OUTCOMES AND MEASURES: Surrogacy of time to nadir and depth of nadir was assessed at the trial level based on joint modeling of relative tumor-size change vs baseline and OS. Treatment effects on time to nadir and on depth of nadir were defined in terms of between-arm differences in time to nadir and in depth of nadir, and both were assessed in linear regressions for their correlation with treatment effects (hazard ratios) on OS within each set. The strengths of association were quantified using sample-size–weighted coefficients of determination (R2), with values closer to 1.00 indicating stronger association. At the patient level, the correlation was assessed between modeled relative tumor-size change and OS. RESULTS: For 14 chemotherapy comparisons in 4289 patients, the R2 value was 0.63 (95% CI, 0.30-0.96) for the association between treatment effects on time to nadir and OS and 0.08 (95% CI, 0-0.37) for depth of nadir and OS. For 11 antiangiogenic agent comparisons (4854 patients), corresponding values of R2 were 0.25 (95% CI, 0-0.72) and 0.06 (95% CI, 0-0.35). For 8 anti–epidermal growth factor receptor comparisons (2684 patients), corresponding values of R2 were 0.24 (95% CI, 0-0.83) and 0.21 (95% CI, 0-0.78). CONCLUSIONS AND RELEVANCE: In contrast with early reports favoring depth of response as a surrogate, these results suggest that neither time to nadir nor depth of nadir is an acceptable surrogate for OS in the first-line treatment of metastatic colorectal cancer

Light preferences of Musca domestica L.

The attractiveness of ultraviolet, blue, green and white light to two strains of Musca domestica L. has been examined in a tunnel. Phototactic behaviour appeared to be affected by the illuminance of the tunnel and depends on the origin of the flies

Sex-, age- and strain-related quantities of muscalure on the cuticula of the housefly (Musca domestica)

Muscalure, (Z)-9-tricosene, is the major component of the cuticular contact sex pheromone of female houseflies, Musca domestica. By means of gas chromatography the relative amounts of muscalure were determined on female and male houseflies of different sex, age and strain. Females and males of mixed (both sexes together in a cage) and isolated (sexes separated) populations of a laboratory WHO Ij2 strain and of two wild type strains from, respectively, a chicken, and a cattle and pig farm in the Netherlands were investigated. The results show that the amounts of muscalure present on the cuticles of the laboratory strain females were 10-40 times higher than those found on females of both wild type strains. No muscalure was found on males from the latter two strains and from isolated WHO populations. However, on males from the mixed population of the WHO strain the amounts of muscalure gradually increased in course of time, which was probably due to transfer of the pheromone from the females to the males as a result of physical contacts between the sexes

Electrophysiological characterization of olfactory receptors in Musca domestica L.

Cluster-analysis of olfactory cells was done; separation between clusters of olfactory cells with comparable properties is not strict. Nevertheless, cells are found reacting to none of the tested chemicals (group A), to all the chemicals (group H), to 1-octen-3-ol mainly (group B,C), to amylacetate mainly (group E) and to different combinations of chemicals (group D,F,G). 1-octen-3-ol is percieved by most cells of the antenna. In the palp, cells are most stimulated by 3-methylphenole (group K) and 2-pentanone (group J)

Houseflies: Effects of age on olfactory responses

The olfactory system of sexually immature 1-day-old flies is already functional. No clear differences exist between the responses of their olfactory cells and those of sexually mature flies to amylacetate, S-methylphenol, 2-pentanone and R(+)-limonene. However, the sensitivity to 1-octen-3-ol is lower in young flies than in old flies

Attraction of the housefly (Musca domestica L)

Ultraviolet (UV) light attracts more houseflies compared to green and white light. The attractiveness of UV light is not effected by its spectral composition. The number of flies attracted does not seem to change when a UV lamp is combined with moving elements, although the time spend on the lamp decreases. A few odours have been examined for their ability to attract houseflies. Hungry flies appeared to be attracted by the odour of manure, meat, fruit, and the diet they have been bred on. When the flies were well-fed, only the manure and tainted meat attracted female flies which were looking for a substrate to deposit their eggs. More odours will be examined for their ability to improve the attractiveness of the ultraviolet light trap