History Matters: Oviposition Resource Acceptance in an Exploiter of a Nursery Pollination Mutualism

The Evolutionary Relevance of Social Learning and Transmission in Non-Social Arthropods with a Focus on Oviposition-Related Behaviors

Research on social learning has centered around vertebrates, but evidence is accumulating that small-brained, non-social arthropods also learn from others. Social learning can lead to social inheritance when socially acquired behaviors are transmitted to subsequent generations. Using oviposition site selection, a critical behavior for most arthropods, as an example, we first highlight the complementarities between social and classical genetic inheritance. We then discuss the relevance of studying social learning and transmission in non-social arthropods and document known cases in the literature, including examples of social learning from con- and hetero-specifics. We further highlight under which conditions social learning can be adaptive or not. We conclude that non-social arthropods and the study of oviposition behavior offer unparalleled opportunities to unravel the importance of social learning and inheritance for animal evolution.

Interactions Between Figs and Gall-Inducing Fig Wasps: Adaptations, Constraints, and Unanswered Questions

The ancient interaction between figs (Ficus, Moraceae) and their pollinating fig wasps is an unusual example of a mutualism between plants and gall-inducing insects. This review intends to offer fresh perspectives into the relationship between figs and the diversity of gall-inducing sycophiles which inhabit their enclosed globular inflorescences that function as microcosms. Besides gall-inducing pollinators, fig inflorescences are also inhabited by other gall-inducing wasps. This review evaluates the state of current knowledge on gall-induction by fig wasps and exposes the many lacunae in this area. This review makes connections between fig and gall-inducing wasp traits, and suggests relatively unexplored research avenues. This manuscript calls for an integrated approach that incorporates such diverse fields as life-history theory, plant mate choice, wasp sexual selection and local mate competition, plant embryology as well as seed and fruit dispersal. It calls for collaboration between researchers such as plant developmental biologists, insect physiologists, chemical ecologists and sensory biologists to jointly solve the many valuable questions that can be addressed in community ecology, co-evolution and species interaction biology using the fig inflorescence microcosm, that is inhabited by gall-inducing mutualistic and parasitic wasps, as a model system.

Cucumber and Tomato Volatiles: Influence on Attraction in the Melon Fly Zeugodacus cucurbitate (Diptera: Tephritidae)

The main hosts of the melon fly Zeugodacus cucurbitate are cultivated and wild cucurbitaceous plants. In eastern Africa, the melon fly is a major pest of the Solanaceae plant Solanum lycopersicum (tomato). We hypothesized that shared species-specific volatiles may play a role in host attraction. We tested this hypothesis by comparing the olfactory responses of the melon fly to Cucumis sativus (cucumber) (Cucurbitaceae) and tomato plant odors in behavioral and electrophysiological assays, followed by chemical analysis to identify the key compounds mediating the interactions. Our results identified 13 shared components between cucumber and tomato plant odors. A synthetic blend of seven of the shared components dominated by monoterpenes at concentrations mimicking the volatile bouquet of cucumber and tomato attracted both sexes of the melon fly. Our results suggest that the presence and quantity of specific compounds in host odors are the main predictors for host recognition in Z. cucurbitate.

The Galling Truth: Limited Knowledge of Gall-Associated Volatiles in Multitrophic Interactions

Galls are the product of enclosed internal herbivory where the gall maker induces a plant structure within which the herbivores complete their development. For successful sustained herbivory, gall makers must (1) suppress the induction of plant defenses in response to herbivory that is usually mediated through the jasmonic acid pathway and involves volatile organic compound (VOC) production, or (2) have mechanisms to cope with herbivory-induced VOCs, or (3) manipulate production of VOCs to their own advantage. Similarly, plants may have mechanisms (1) to avoid VOC suppression or (2) to attract galler enemies such as parasitoids. While research on VOCs involved in plant-herbivore-parasitoid/predator interactions is extensive, this has largely focussed on the impact of piercing, sucking, and chewing external herbivores or their eggs on VOC emissions. Despite the importance of gallers, owing to their damage to many economically valuable plants, the role of volatiles in gall-associated herbivory has been neglected; exceptions include studies on beneficial gallers and their enemies such as those that occur in brood-site pollination mutualisms. This is possibly the consequence of the difficulties inherent with studying internally occurring herbivory. This review examines the evidence for VOCs in galler attraction to host plants, potential VOC suppression by gallers, increased emission from galls and neighboring tissues, attraction of galler enemies, and the role of galler symbionts in VOC production. It suggests a research focus and ways in which studies on galler-associated VOCs can progress from a philatelic approach involving VOC listing toward a more predictive and evolutionary perspective.