Brewer’s yeast, Saccharomyces cerevisiae, enhances attraction of two invasive yellowjackets (Hymenoptera: Vespidae) to dried fruit and fruit powder

The German yellowjacket, Vespula germanica F., and common yellowjacket, Vespula vulgaris L. (Hymenoptera: Vespidae), are pests of significant economic, environmental, and medical importance in many countries. There is a need for the development and improvement of attractive baits that can be deployed in traps to capture and kill these wasps in areas where they are a problem. Yellowjackets are known to feed on fermenting fruit, but this resource is seldom considered as a bait due to its ephemeral nature and its potential attractiveness to nontarget species. We analyzed the headspace volatiles of dried fruit and fruit powder baits with and without Brewer’s yeast, Saccharomyces cerevisiae, using gas chromatography–mass spectrometry, and we field tested these baits for their attractiveness to yellowjackets in Argentina. The addition of yeast to dried fruit and fruit powder changed the volatile compositions, increasing the number of alcohols and acids and decreasing the number of aldehydes. Dried fruit and fruit powder baits on their own were hardly attractive to yellowjackets, but the addition of yeast improved their attractiveness by 9- to 50-fold and surpassed the attractiveness of a commercial heptyl butyrate-based wasp lure. We suggest that further research be done to test additional varieties and species of yeasts. A dried fruit or fruit powder bait in combination with yeast could become a useful tool in the management of yellowjacketsFil: Babcock, Tamara. Simon Fraser University. Department of Biological Sciences; CanadaFil: Gries, Regine. Simon Fraser University. Department of Biological Sciences; CanadaFil: Borden, John. Scotts Canada; CanadaFil: Palmero, Luis. Simon Fraser University. Department of Biological Sciences; CanadaFil: Mattiacci, Analia. Consejo Nacional de Investigaciones Científicas y Técnicas-Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; Argentina.Fil: Masciocchi, Maite. Consejo Nacional de Investigaciones Científicas y Técnicas-Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; Argentina.Fil: Corley, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas-Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Gries, Gerhard. Simon Fraser University. Department of Biological Sciences; Canad

Semiochemical communication between yellowjacket wasps and their yeast symbionts

My research investigated whether (i) symbiotic yeasts isolated from the digestive tract of social wasps, (ii) commercial yeasts, or (iii) the volatiles these yeasts produce can be used as trap baits for capturing yellowjackets. I found that adding brewer’s yeast to dried fruit and fruit powder enhanced attraction of yellowjackets in Argentina. I also found that the two yeast species Hanseniaspora uvarum and Lachancea thermotolerans, isolated from North American yellowjackets and grown on grape juice-infused agar, attract yellowjackets. Lachancea thermotolerans in admixture with fruit powder was also attractive and expressed an additive effect when combined with a commercial wasp lure. Synthetic analog blends of the volatiles produced by H. uvarum growing on grape juice-infused media and L. thermotolerans growing on fruit powder were both attractive to western yellowjackets, but not to other yellowjackets. In summary, symbiotic yeasts and their semiochemicals, respectively, show potential as yellowjacket trap baits or lures

Global synthesis of sea turtle von Bertalanffy growth parameters through Bayesian hierarchical modeling

Knowledge of sea turtle demographic rates is central to modeling their population dynamics, but few studies have quantitatively synthesized existing data globally. Here, we used a Bayesian hierarchical model to conduct a meta-analysis of published von Bertalanffy growth curve parameters (growth coefficient, K; asymptotic length, L∞) for chelonid sea turtles. We identified 34 studies for 5 of 6 extant chelonids that met minimum selection criteria. We implemented a suite of models that included a multivariate normal likelihood on the log-transformed values of the 2 parameters to evaluate the influence of species, population (regional management unit, RMU), parameter estimation method (mark-recapture, skeletochronology, length-frequency analysis), latitude, and sampled body size range (all sizes, no large, no small, no large or small) on growth parameter estimates. According to information criteria, the best model included a random effect of species. The second best model also included latitude as a fixed effect, but RMU, parameter estimation method, latitude, and sampled body size ultimately did not strongly influence the means or variances of K and L∞ among studies. The apparent lack of RMU effect on parameter estimates within species may be an artifact of the small number of RMUs with published growth parameter estimates. The species-specific, and in some cases RMU-specific, posterior means and standard deviations of K and L∞ from this study would be appropriate priors for future studies of growth in chelonid sea turtles or for models of population dynamics. We highlight the need for expanded study and synthesis of sea turtle somatic growth rates