Four years host–parasitoid food web: testing sampling effort on trophic levels

Can multitrophic interactions shape morphometry, allometry, and fluctuating asymmetry of seed-feeding insects?

Body size is commonly associated with biological features such as reproductive capacity, competition, and resource acquisition. Many studies have tried to understand how these isolated factors can affect the body pattern of individuals. However, little is known about how interactions among species in multitrophic communities determine the body shape of individuals exploiting the same resource. Here, we evaluate the effect of fruit infestation, parasitism rate, and seed biomass on size, allometric and asymmetric patterns of morphological structures of insects that exploit the same resource. To test it, we measured 750 individuals associated with the plant Senegalia tenuifolia (Fabaceae), previously collected over three consecutive years. Negative allometry was maintained for all species, suggesting that with increasing body size the body structure did not grow proportionally. Despite this, some variations in allometric slopes suggest that interactions in a multitrophic food web can shape the development of these species. Also, we observed a higher confidence interval at higher categories of infestation and parasitism rate, suggesting a great variability in the allometric scaling. We did not observe fluctuating asymmetry for any category or species, but we found some changes in morphological structures, depending on the variables tested. These findings show that both allometry and morphological trait measurements are the most indicated in studies focused on interactions and morphometry. Finally, we show that, except for the fluctuating asymmetry, each species and morphological structure respond differently to interactions, even if the individuals play the same functional role within the food web.

Herbivore, parasitoid and hyperparasitoid insects associated with fruits and seeds of Enterolobium contortisiliquum (Vell.) Morong (Fabaceae)

This study aimed to inventory the herbivore insects associated with Enterolobium contortisiliquum (Vell.) Morong (Fabaceae) fruits and seeds and their primary and secondary parasitoids. Six samples collected between May and October 2013 yielded 210 fruits, from which 326 insects of six orders emerged: Coleoptera, Hymenoptera, Lepidoptera, Diptera, Thysanoptera and Psocoptera. Coleoptera (five families) was represented by the seed consumers Merobruchus bicoloripes Pic, Stator sp. Bridwell (Chrysomelidae, Bruchinae), two species of Silvanidae, one species of Scolytinae (Curculionidae), one species of Nitidulidae and one species of Cerambycidae. The cerambycid was also observed forming galleries on fruit mesocarp. Immature individuals of Lepidoptera were observed consuming the fruits and seeds. From the seven Hymenoptera families, only two species were associated with Coleoptera, being Horismenus Walker sp. (Eulophidae) as parasitoid of M. bicoloripes, and Neoheterospilus falcatus (Marsh) (Braconidae) as parasitoid of Scolytinae. The Lepidoptera parasitoids represented four genera: Pseudophanerotoma Zetel, Chelonus Panzer (Braconidae), Orgilus Nees (Braconidae) and Goniozus Forster (Bethylidae). The host associations for the reared parasitoids Bracon Fabricius (Braconidae), Pimplinae sp. (Ichneumonidae) and Perilampus Forster (Perilampidae) were not confirmed. We obtained a single representative of Diptera (Tachinidae) associated with Lepidoptera hosts in this food web.