Possible pathogens of social wasps (Hymenoptera: Vespidae) and their potential as biological control agents

Abstract

Boutin et al. (2006) claimed that American and Eurasian red squirrels use an unknown environmental cue to anticipate the availability of the abundant food of an autumn seed mast, and produce more young than usual in the previous spring and summer. But these small mammals need increased supplies of protein to produce and support young, therefore they must have had access to some other protein‐rich food that was available before the mast was ripe. There are other small mammalian seed‐eaters that increase their reproductive output ahead of the maturation of a seed mast. It seems likely that, in each case, females are able to produce extra young in advance because they eat the amino acid‐rich inflorescences and unripe seeds of the mast and/or larval insects that also increase their numbers in the spring of a mast year by eating the same enriched plant food.     

Observations on the life history of Limnodrilus hoffmeisteri (Annelida,Tubificidae) from the Little Calumet River in temperate North America

The reproductive period for L. hoffmeisteri as observed in the Little Calumet River (41°34′22″N. 87°28′30Prime;W) occurs from early fall through late spring. The period is marked by the development of the reproductive organs in the early fall months, followed by the development of sperm products within the sperm sac. The female organs appear to mature in middle to late winter with the appearance of nutritive granules followed by the developing eggs in early spring. This cycle is completed in early to late spring with the appearance of cocoons containing developing embryos. It is also apparent that a low level of reproductive activity occurs throughout the rest of the year. This is usually observed in worms with developed sperm sacs and sperm products, having matured penis and some developed egg sacs with nutritive granules. Eggs have not been observed during this low level of reproductive activity.     

WOLBACHIA INFECTION IN DROSOPHILA SIMULANS: DOES THE FEMALE HOST BEAR A PHYSIOLOGICAL COST?

Fitness traits of three Drosophila simulans strains infected by endocellular bacteria belonging to the genus Wolbachia have been compared with those of replicate stocks previously cured from the infection by an antibiotic treatment. The traits measured were development time, egg-to-adult viability, egg hatch, productivity, fecundity, and the number of functional ovarioles. Individuals of the first strain were bi-infected by two Wolbachia variants, wHa and wNo. The second strain was infected by wHa, the third one by wNo. The Wolbachia studied here cause cytoplasmic incompatibility (CI), a high embryonic mortality (70% to > 90%) when an infected male is crossed with an uninfected female. Three generations after antibiotic treatment, we observed in all strains a significant drop in productivity in the cured stocks. This drop was not due to antibiotic toxicity and was associated with the loss of the Wolbachia. However the effect had disappeared in two of the three strains five generations after treatment, and could not be found in the third strain in a third measurement carried out 14 generations after treatment. The temporary nature of the productivity difference indicates that Wolbachia do not enhance productivity in infected strains. On the other hand, in all traits measured, our results show the absence of any negative effects of the Wolbachia on their host. This could be explained when considering Wolbachia evolution, as maternally transmitted parasites bear a strong selective pressure not to harm their female host. However, CI would allow the bacteria to be maintained even when harming the female. The apparent absence of deleterious effects caused by these Wolbachia might result from a trade-off, where a relatively low bacteria density would advantage the Wolbachia by suppressing any deleterious effects on the female host, at the cost of a weaker maternal transmission rate of the infection.     

Clinical applications of physical anthropology

In recent decades physical anthropology has moved from its more traditional confines into many areas of clinical interest including growth and development, nutrition, clinical medicine, dysmorphology, and physical fitness. The “clinical applications” of physical anthropology is a broad topic, given the space limitations of a review. Hence, selected clinical applications, emphasizing anthropometry at the expense of physiology and genetics, are considered. Since the author is a pediatrician, the review concentrates largely on areas dealing with children.     

Some reflections on evolutionary theories,With a classification of fitness

Using a classical life history model (the Smith & Fretwell model of the evolution of offspring size), it is demonstrated that even in the presence of overwhelming empirical support, the testability of predictions derived from evolutionary models can give no guarantee that the underlying fitness concept is sound. Non-awareness of this problem may cause considerable justified but avoidable criticism. To help understanding the variable use of fitness in evolutionary models and recognizing potentially problematic areas which need careful consideration, a hierarchical classification of definitions of fitness used in evolutionary models is presented. As a conclusion, it is advocated to use the term fitness more conscientiously than currently often practised and to think more about ways to develop fitness-free evolutionary theories compatible with Darwin's ideas.     

Sterilization of Hulecoeteomyia japonica japonica (= Aedes japonicus japonicus) (Theobald, 1901) by high‐energy photon irradiation: implications for a sterile insect technique approach in Europe

Hulecoeteomyia japonica japonica (= Aedes japonicus japonicus) (Diptera: Culicidae) (Theobald 1901), a container‐breeding invasive species in North America and Europe, is attracting particular attention for its high local abundances and possible roles in the transmission of human and animal pathogens. The preferential habitats of this species are forested and bushy areas, which renders control measures extremely inefficient. Use of the sterile insect technique (SIT) may contribute to the implementation of area‐wide integrated pest management strategies, as has been successfully proven with other aedine mosquito species. The present study investigates the effects of irradiation at a dose of 40 Gy on fitness parameters in H. j. japonica. Irradiation was performed on 16–24‐h‐old pupae from a colonized strain (PA) using a TrueBeam linear accelerator. Males from the PA strain were crossed with females of the same colony or with field‐collected females. Irradiation induced a slight increase in mortality in male pupae, but did not alter the survival and mating abilities of emerging adult males. Rates of blood feeding and fertility were lower when PA strain males were kept with field‐collected females rather than PA females. Irradiated males induced reductions in fertility (residual fertility: 2.6%) and fecundity in mated females. The data indicate that the SIT is a suitable technique to enhance the control of this species.