Extreme suction attachment performance from specialised insects living in mountain streams (Diptera: Blephariceridae)

Suction is widely used by animals for strong controllable underwater adhesion but is less well understood than adhesion of terrestrial climbing animals. Here we investigate the attachment of aquatic insect larvae (Blephariceridae), which cling to rocks in torrential streams using the only known muscle-actuated suction organs in insects. We measured their attachment forces on well-defined rough substrates and found that their adhesion was less reduced by micro-roughness than that of terrestrial climbing insects. In vivo visualisation of the suction organs in contact with microstructured substrates revealed that they can mould around large asperities to form a seal. We have shown that the ventral surface of the suction disc is covered by dense arrays of microtrichia, which are stiff spine-like cuticular structures that only make tip contact. Our results demonstrate the impressive performance and versatility of blepharicerid suction organs and highlight their potential as a study system to explore biological suction mechanisms.

Food items and feeding habits of two Nothobranchiidae, Epiplatys chaperi sheljuzhkoi (poll, 1953) and Nimbapanchax petersi (sauvage, 1882) in Banco river, Côte d’ivoire

Food and feeding habits of two Nothobranchiidae species, Epiplatys chaperi sheljuzhkoi (Poll, 1953) and Nimbapanchax petersi (Sauvage, 1882) from Banco River were investigated between January and December 2016. Stomach contents of 119 and 397 individuals of E. sheljuzhkoi and N. petersi were respectively analyzed, ranging in size from 13 and 55 mm, 11 and 48 mm standard Length, respectively. Formicidae being terrestrial insects, constituted the main prey (RI>50) of both species, and aquatic insect larvae (Hydrophilidae and Chironomidae) were secondary or accessory preys. The food items in stomach showed a small spectrum in E. sheljuzhkoi than N. petersi but differences were not significant (Chi-square, p>0.05). Diet composition of both species showed little variation according to seasons, sampling zones and size groups (Anova, p>0.05). However, a decreasing trend in terrestrial insects and an increase of other preys in stomach contents has been observed from upstream to downstream. For ontogenic variation, large specimens group fed much more on aquatic insect larvae, fish scales and macrophytes than small size group. This work indicated that both species fed on a small range of prey items dominated by insects in Banco River and could be considered strict insectivorous predators. This work concludes that both species have similar diets and the canopy cover of Banco forest plays an important role in the feeding and conservation of these species. Key words: Epiplatys, Nimbapanchax, canopy cover, diet, terrestrial insects, Formicidae, predator.

Cultivable cellulolytic fungi isolated from the gut of Amazonian aquatic insects

ABSTRACT Filamentous fungi have been targeted by bioprospecting studies because they are effective producers of extracellular enzymes that can potentially be used by the bioindustry. In this study, we isolated filamentous fungi from the guts of Amazonian aquatic insect larvae to evaluate their cellulolytic activity. We collected 69 larvae of shredder insects of three genera: Phylloicus (Trichoptera: Calamoceratidae), Triplectides (Trichoptera: Leptoceridae) and Stenochironomus (Diptera: Chironomidae) in ten streams from a protected area in the central Brazilian Amazon. Production of mycelia was elaborated in PDA (Potato Dextrose Agar) medium. The isolates were transferred to a synthetic medium with carboxymethyl cellulose, and Congo red was used to determine the enzymatic index. The hydrolysis halo, indicating the production of cellulases, was observed in 175 fungal isolates (70% of the total), of which 25 had an enzymatic index ≥ 2.0 and belonged to seven fungal genera. The fungal taxa Cladosporium, Gliocephalotrichum, Penicillium, Pestalotiopsis, Talaromyces, Trichoderma and Umbelopsis were isolated from guts of Phylloicus, Triplectides and Stenochironomus, which are traditionally used in biotechnological applications. Our results indicate the cellulolytic potential of fungi associated with the guts of aquatic Amazonian insects.

Effects of bromeliad flowering event on the community structuring of aquatic insect larvae associated with phytotelmata of Aechmea distichantha Lem. (Bromeliaceae)

Aim: We aimed to understand how aquatic insect larvae communities associated with bromeliad phytotelmata are affected by plant architecture, predators and resources (local factors), and by geographical distance (regional factors) in two different plant phenological phases. Bromeliad flowering results in plant structural changes, which favours insect dispersal. Considering that local and regional factors may affect the community of aquatic insect larvae, we expected that composition, beta diversity and the importance of those factors would differ in the vegetative growth and flowering phases. Methods We performed six samplings of the bromeliad associated fauna in 2010, three during the first semester - vegetative growth phase - and three during the second semester - flowering phase. In each sampling, we collected 12 plants along the rocky walls with similar location distribution, with a total of 72 bromeliads studied. Results Although beta diversity (PERMDISP) did not differ between vegetative growth and flowering, NMDS followed by ANOSIM showed that composition was significantly different in the distinct phenological phases. IndVal results showed that three Diptera morphospecies were discriminant of the vegetative growth phase. In addition, pRDA revealed differences in the relative contribution of local and regional factors to explain insect larvae community structure. During the flowering phase, local factors predominated, while during vegetative growth, regional factors were more important. Conclusion Differences in dispersal rates between the two phenological phases, likely due to adult insect pollination and further oviposition, influenced community structuring. Therefore, flowering events account for differences not only in the composition, but also in community structuring of aquatic insect larvae inhabiting the phytotelmata of Aechmea distichantha Lem. (Bromeliaceae).

In vitro infection experiments with eggs of the nematode Contracaecum rudolphii Hartwich, 1964 (sensu lato) targeting aquatic insect larvae (Odonata: Coenagrionidae and Libellulidae; Trichoptera: Integripalpia) as possible intermediate hosts

The availability of aquatic insects (Odonata: Coenagrionidae, Libellulidae and Trichoptera: Integripalpia) as potential intermediate hosts for the nematode Contracaecum rudolphii Hartwich, 1964 sensu lato was studied under laboratory conditions. The infective material consisted of nematode eggs, newly hatched larvae, as well as in vitro infected cyclopoid copepods. High prevalence and intensity of infection associated with a low mortality of aquatic insect larvae suggests that they may serve as intermediate hosts for C. rudolphii and constitute a major reservoir of C. rudolphii larvae in aquatic habitats.