The Pupal Parasitoid Trichopria drosophilae Is Attracted to the Same Yeast Volatiles as Its Adult Host

Journal of Chemical Ecology - There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore...     

Adult Parasitoids of Honeydew-Producing Insects Prefer Honeydew Sugars to Cover their Energetic Needs

To meet their carbohydrate requirements, adult parasitoids exploit a broad range of sugar resources, including floral and extrafloral nectar and honeydew. Although honeydew might be the predominant sugar source, especially in agricultural systems, it often is nutritionally inferior to sugar sources like nectar. Given its broad availability, it may be expected that sugar-feeding insects have evolved specialized adaptations to deal with this typically inferior sugar source. This would apply especially to organisms that have a close association with honeydew producers. Here, we hypothesized that parasitoids of honeydew-producing insects should show a pronounced response to sugars, such as fructose, sucrose, melezitose, and trehalose, and to a lesser extent glucose. To test this hypothesis, we investigated sugar consumption, feeding behavior and survival of the aphid parasitoid Aphidius ervi on several sugars (equiweight solutions). Our results show that A. ervi adults consumed typical honeydew sugars (sucrose, fructose, trehalose, and melezitose) the most, while consuming considerably less glucose or melibiose. Rhamnose, which does not occur in aphid honeydew, was not, or was only marginally, consumed. When different sugars were provided at the same time, A. ervi adults preferred sucrose or fructose over glucose or melezitose. Furthermore, pre-exposure to sucrose or fructose significantly reduced subsequent intake of glucose, suggesting an acquired distaste for glucose after being previously exposed to highly preferred sugars such as sucrose and fructose. Altogether, this study shows that A. ervi adults prefer sugars (fructose, melezitose, trehalose, and sucrose) that are overrepresented in aphid honeydew and show a lower preference to one (glucose) that is underrepresented in honeydew.     

Distribution of PCBs and organochlorine pesticides in umbilical cord and maternal serum

Polychlorinated biphenyls (PCBs) and organochlorine pesticides, such as hexachlorobenzene (HCB) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE) are compounds widespread in the environment, highly lipophilic, and accumulate in biological systems. The newborn are exposed to these organochlorine compounds across the placenta and through breastfeeding. This study reports the levels of selected PCB congeners, p,p'-DDE and HCB in maternal blood and cord blood samples collected at delivery between November and December 1999 from 44 women living in the urban area of Antwerp, Belgium. Results show that all newborns contained detectable levels of PCBs, p,p'-DDE and HCB. The median concentration of PCBs was 450 pg/ml and ranged between 120 and 1580 pg/ml, while the median concentrations of HCB and p,p'-DDE were 70 and 490 pg/ml, respectively. Concentrations of PCBs and p,p'-DDE in cord blood (ng/ml) were positively associated with concentrations in maternal blood (ng/ml) (coefficients=0.74 and 0.92, P<0.05). We conclude that all investigated organochlorine compounds have an efficient transplacental transfer.