In Mediterranean vineyards the European grapevine moth, Lobesia botrana, usually completes three non-overlapping larval generations per year. Larvae feed on inflorescences and unripe or ripe grapes. Previous work has shown that the larval food source has a huge effect on adult size and fitness. We investigated if larval food also affects the propensity of females to mate polyandrously. Levels of polyandry were monitored with baited traps in a vineyard for two years and then compared with data from laboratory trials using vine-reared individuals. In the field, polyandry levels followed a cyclic annual pattern associated with the larval food source. Large females that fed on ripe grapes exhibited significantly higher levels of polyandry than smaller females that fed on inflorescences. Females that fed on unripe grapes showed intermediate levels of remating. Polyandry also tended to increase later in each flight. Laboratory trials confirmed a direct effect of larval feeding on levels of polyandry. Overall, these results showed that the seasonal variation in polyandry exhibited by L. botrana in the field occurs, at least in part, because of food-derived changes regulating female size. Results also suggested that larval feeding could shape sexual size dimorphism and polyandry levels. Larval nutrition should therefore be considered as an important ecological factor by those studying the evolutionary significance of polyandry and sperm competition in the Lepidoptera.

Phytophthora nicotianaeis the pathogen that causes root and crown rot disease in open field paprika pepper crops of Extremadura (central-western Spain). A field experiment was established during spring, a period compatible with the pepper crop cycle in this region, to evaluate the effects of biofumigation with pellets ofBrassica carinatadefatted seed meal, at the rate recommended by the manufacturer (3 tons ha⁻¹), on the survival and infectivity ofP. nicotianaechlamydospores inoculum. Furthermore, three biofumigant rates (3, 6, and 20 tons ha⁻¹) were assayed in laboratory experiments with natural soil inoculated with chlamydospores. In the field trial, the incorporation of pellets at 3 tons ha⁻¹did not produce remarkable changes in soil enzyme activity or soil properties. In both the field and laboratory tests, survival and infectivity in the biofumigated treatment at 3 tons ha⁻¹did not differ from those in the untreated control. On the contrary, the same rate added to autoclaved soil completely suppressed the inoculum, suggesting that the soil microbiota degradesB. carinatapellets before being effective againstP. nicotianae. Increasing the recommended rate to 6 tons ha⁻¹decreased inoculum survival in the laboratory test and 20 tons ha⁻¹completely inhibited the inoculum, although the economic value of such a high rate application is a factor to be assessed. In phytotoxicity tests on radish and white mustard seeds with several concentrations (100, 50, 25, 10, 5, and 0%) ofB. carinatapellets solution, no phytotoxic effect was observed with the two lowest concentrations, and no symptoms of phytotoxicity were found in the bioassays of pepper plants.

Chestnut blight, caused by Cryphonectria parasitica, is a severe disease that may be biologically controlled by the use of hypovirulent strains, but the diversity of the pathogen population affects biocontrol feasibility. Villuercas–Ibores–Jara, the Jerte Valley and La Vera are the main chestnut production districts in Cáceres (central-western Spain). The purpose of this study is to determine the Vegetative Compatibility Groups (VCGs) and mating types in these districts and to identify hypovirulent isolates to be used in biological control. The VCGs were determined by the merging/barrage response; PCR tests were used for the mating type determination and CHV-1 hypovirus detection. In total, 40 sites were surveyed and 269 isolates were obtained, most of them (227) from the Villuercas–Ibores–Jara district, where EU11 was the predominant VCG (88.1%) with EU1 (6.6%) and EU12 (4.4%) being also present. In the Jerte Valley and La Vera, EU1 (61.9%), EU11 (11.9%) and EU12 (11.9%) were the predominant VCGs. Both mating types were detected (48% MAT-1; 50% MAT-2) and in general, only one mating type was found in each site. The presence of Cryphonectria hypovirus 1 (CHV-1), subtype I, was identified in only one isolate (VCG EU11) from Villuercas–Ibores–Jara. The characteristics of the C. parasitica population in this district and the occurrence of CHV-1 hypovirus support the potential of successful biological control in Villuercas–Ibores–Jara using hypovirulent strains, while in the Jerte Valley and La Vera only preventive measures are recommended.