Plants grow in communities where they interact with other plants and with other living organisms such as pollinators. On the one hand, studies of plant–plant interactions rarely consider how plants interact with other trophic levels such as pollinators. On the other, studies of plant–animal interactions rarely deal with interactions within trophic levels such as plant–plant competition and facilitation. Thus, to what degree plant interactions affect biodiversity and ecological networks across trophic levels is poorly understood. We manipulated plant communities driven by foundation species facilitation and sampled plant–pollinator networks at fine spatial scale in a field experiment in Sierra Nevada, Spain. We found that plant–plant facilitation shaped pollinator diversity and structured pollination networks. Nonadditive effects of plant interactions on pollinator diversity and interaction diversity were synergistic in one foundation species networks while they were additive in another foundation species. Nonadditive effects of plant interactions were due to rewiring of pollination interactions. In addition, plant facilitation had negative effects on the structure of pollination networks likely due to increase in plant competition for pollination. Our results empirically demonstrate how different network types are coupled, revealing pervasive consequences of interaction chains in diverse communities.

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Climatic conditions and the physiological state of a parasitoid may alter its host selection behavior and thus its efficiency as a biological control agent. We studied the influence of these parameters on the behavior of Fopius arisanus (Sonan), an egg-pupal parasitoid of many Tephritidae. In the first experiment, we assessed in field cage assays the influence of temperature, humidity, light intensity, barometric pressure, and wind speed. Both flight and parasitism were mainly affected by temperature and humidity. However, because these two factors were strongly correlated in our experiments, the direct influence of each one cannot be specified. Flight activity was affected by variations in barometric pressure. In a second set of experiments, we conducted release and recapture assays with dyed insects to determine the influence of sex, mating status, egg load, age, and starvation on attraction toward infested fruit. Males were not attracted, suggesting that fruit are not a mating site. The egg load seemed to be a major parameter of foraging motivation. Finally, we showed that flight activity strongly decreased after 48 h of starvation. We observed a possible switch to food in the foraging motivation of starved females, but this result was impaired by poor recoveries: <10% of released females were recaptured after 96 h of starvation. We finally discuss the importance of these observations on the efficiency of F. arisanus as a biological control agent in tropical humid areas.

The identification of infochemicals for parasitoid females is a critical issue in applied and fundamental parasitoid research. The olfactory location of host and its microhabitat by Fopius arisanus (Sonan, 1932) (Hymenoptera: Braconidae), an egg-pupal parasitoid of fruit flies (Diptera: Tephritidae), is investigated. Potential sources of volatiles are placed in opaque traps and tested in field cages, under seminatural conditions. Fopius arisanus females respond positively to synomones from mango leaves and from fruits belonging to many botanical families, including the nonhost plant strawberry. They prefer fruits infested by Tephritidae to uninfested ones but do not discriminate between fresh and old infestations. Fopius arisanus females are attracted by the odours of faeces of the tephritid fly Bactrocera zonata . They exhibit remote detection of a volatile kairomone coating the egg mass of all tested Tephritidae species but absent in the egg mass of the Muscidae Stomoxys calcitrans . All these infochemicals are volatile but only those emanating from fruit and from faeces are attractants perceived before landing. The relationships between this apparent generalist behaviour and the dietary specialization of F. arisanus are discussed, according to its ecology and behaviour in its natural environment.