Parasitoids as well as many of their herbivorous hosts, depend on carbohydrate-rich food during the adult stage. Different types of nectar and honeydew vary with regard to their sugar composition. In order to successfully exploit a food source, the insect must show a positive gustatory response to its component sugars and be able to digest and metabolise them. Here we tested the herbivore Plutella xylostella L. (Lepidoptera: Plutellidae) and its parasitoid Diadegma semiclausum (Hellén) (Ichneumonidae: Campopleginae) with respect to their feeding response and longevity when provided with one of nine sugars (fructose, glucose, lactose, maltose, melibiose, melezitose, raffinose, sucrose, or trehalose). Both species responded to and showed a prolonged life span on a broad range of sugars. The impact of food supply on life span was about sixfold higher for the parasitoid than for the herbivore. In general, there was a good fit between gustatory response and achieved longevity, with some outliers. Both species showed only weak responses to melibiose, which significantly prolonged life span. The parasitoid showed a gustatory response to melezitose, which did not prolong its life span. The parasitoid and its herbivorous host responded differently to trehalose. These differences in gustatory response and longevity show the potential for application of selective sugar sources in conservation biological control. At the same time it also reveals a risk that the indiscriminate application of sugar sources may stimulate herbivory.

Hungarian authors have long been discussing the role of earthworms in improving soil productivity. Earthworm counts in our higher quality soils are similar to those found in soils where more attention is paid to earthworm activity. Negative impacts that are independent of farming—such as sustained dry spells in the summer—also affect earthworm counts. Negative impacts that definitely depend on farming include land use causing soil moisture loss, deep stubble treatment leaving the soil without cover, and ploughing in the summer without subsequent pressing. The climate change is having both positive and negative impacts. Weather patterns are causing losses but adopting climate mitigating tillage are generating benefits. In the trials results so far show that tillage focusing on preserving soil moisture, structure, and organic materials, covering the surface in the critical months as well as adequate soil loosening are fundamental pre-requisites for making the soil a favourable habitat for earthworms.

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