Koinobint life style of the spider wasp Minagenia (Hymenoptera, Pompilidae) and its consequences for host selection and sex allocation

Evolutionary aspects of the parasitoid life strategy, with a particular emphasis on fly–spider interactions

Parasitoids are significant ecological elements of terrestrial food webs and have evolved within seven insect orders. Interestingly, however, associations with spiders as hosts have evolved only in two insect orders, Diptera and Hymenoptera. Here, we summarize various aspects of host utilization by dipteran flies with an emphasis on associations with spiders. Our synthesis reveals that spider flies (family Acroceridae) have evolved a unique life strategy among all the parasitoid taxa associated with spiders, in which koinobiont small-headed flies utilize an indirect oviposition strategy. This indirect oviposition in spider flies is inherited from Nemestrinimorpha ancestors which appeared in the Late Triassic and is characterized by the evolution of planidial larvae. Further, we discuss the advantages and disadvantages of indirect oviposition in spider flies. On the one hand, indirect oviposition allows the fly to avoid contact/wrestling with spider hosts. On the other hand, larval survival is low because the planidium must actively seek out and infect a suitable host individually. The risk of failure to find a suitable spider host is offset by the fly’s extremely high fecundity.

Ecosystem services provided by aculeate wasps

The aculeate wasps are one of the most diverse and speciose insect taxa; they are omnipresent across ecosystems and exhibit diverse co-evolutionary and exploitative associations with other organisms. There is widespread conjecture that aculeate wasps are likely to perform essential ecological and economic services of importance to the health, well-being and nutritional needs of our planet. However, the scope and nature of the ecosystem services they provide are not well understood relative to other insect groups (e.g. bees, butterflies, beetles); an appreciation of their value is further tarnished by their public reputation as pointless pests. Here, we conduct the first comprehensive review of how aculeate wasps contribute to the four main areas of ecosystem services: regulatory, provisioning, supporting and cultural services. Uniting data from a large but previously disconnected literature on solitary and social aculeate wasps, we provide a synthesis on how these insects perform important ecosystem services as parasites, predators, biological indicators, pollinators, decomposers and seed dispersers; and their additional services as a sustainable alternative to meat for human consumption, and medicinal potential as sources of research leads for anti-microbials and cancer treatments. We highlight how aculeate wasps offer substantial, but largely overlooked, economic benefits through their roles in natural pest management and biological control programs. Accordingly, we provide data-driven arguments for reasons to consider the ecosystem service value of aculeate wasps on a par with other 'useful' insects (e.g. bees). Finally, we provide a research roadmap identifying the key areas of research required to capitalise better on the services provided by these important insects.