The impact of body size on Aedes [Stegomyia] aegypti wingbeat frequency: implications for mosquito identification

Billions of people are at risk due to mosquito-borne diseases. Ideally, the control of mosquito-borne diseases should integrate mosquito control and surveillance to maximize transmission prevention while minimizing environmental impacts. Mosquito surveillance is often limited in scope by logistical constraints, especially the labour and expertise in identifying captured mosquitoes. Mosquito sounds, primarily the wingbeat frequencies (WBF), have been extensively studied in the literature, often targeting a straightforward assessment of this technology with species identification in laboratory conditions. Optical sensors for measuring the WBF of free-flying mosquitoes are the most recent proposal to automate species identification. However, many of the factors that may influence WBF within and between species have not been fully examined, resulting in failures in the species identification. Here we show that body size and temperature modify the wingbeat frequency of female Aedes [Stegomyia] aegypti Linnaeus (Diptera:Culicidae) and such an optical sensor can capture these alterations. We demonstrate that this study's optical sensor can distinguish wingbeat frequency from large and small mosquitoes at different temperatures. The relationship between WBF and size should be taken into account to improve the accuracy of devices that automatically identify species using WBF.

Lumbriculus variegatus (Müller, 1774) (Oligochaeta, Lumbriculidae) in Campos do Jordão State Park, São Paulo, Brazil

The aim of this paper was recording the occurrence of the species Lumbriculus variegatus (Müller, 1774) (Oligochaeta, Lumbriculidae) in lotic systems of the State of São Paulo. Specimens were collected in Sapucaí River, located in Campos do Jordão State Park. The mapping of geographical distribution of this species is of interest to public health since L. variegatus may be an intermediate host of Dioctophyme renale (Goeze, 1782) (Nematoda, Dioctophymatidae), a parasite of recognized zoonotic potential. Distribution data serves as a basis for environmental monitoring and evaluation, being essential to map possible cases of the disease (Dioctophimosis) and provide information to health professionals.

The use of an Allonais inaequalis reproduction test as an ecotoxicological bioassay

Ecotoxicological bioassays have been widely utilized to evaluate the toxicity of substances to organisms. However, the main challenge for researchers is finding native species to assess the effects of pollutants on aquatic biota. The tropical Oligochaeta, Allonais inaequalis, can be used as a test organism in bioassays to understand the effects of toxicants on aquatic ecosystems and their impact on native aquatic biota. In this study, we tested four methodological designs to validate the use of our "Allonais inaequalis reproduction test" as an ecotoxicological bioassay. For each sample, the assay consisted of a bottle containing 10 mg of sterilized fine sand, 60 mL of dechlorinated tap water and 6 organisms, fed at the beginning of the test and again after 5 days. The assay was first established in a controlled environment and then used to evaluate a stressed environment containing one of the following three toxicants suggested by the OECD (2008) and Corbi et al. (2015): zinc chloride, copper sulfate, or potassium chloride. Our results showed that the best experimental design for reproduction analysis was a static, long-term bioassay, which lasted 10 days without aeration and allowed for the reproduction of multiple generations (10 ± 5 new organisms). The observed inhibition reproduction by toxicants (EC50 ranging between 0.2 mg L^-1 and 1.36 g L^-1) validated the methods used in this paper. The use of a reproduction endpoint is a new contribution to the ecotoxicological toolbox, examining responses from a native organism to predict the effects of pollutants in an aquatic environment.

Aquatic insect community structure under the influence of small dams in a stream of the Mogi-Guaçu river basin, state of São Paulo

The fragmentation of lotic systems caused by construction of dams has modified many aquatic communities. The objective of this study was to analyse changes in the aquatic insect community structure by discontinuity of habitat created by dams along the Ribeirão das Anhumas, a sub-basin of the Mogi-Guaçu River (state of São Paulo, Brazil). Entomofauna collection was carried out in 10 segments upstream and downstream of five dams along the longitudinal profile of the stream, with a quick sampling method using a D net (mesh 250 mm) with 2 minutes of sampling effort. The insects were sorted and identified to the lowest possible taxonomic level and analysed by the Shannon diversity index, β diversity, richness estimated by rarefaction curves and relative participation of functional feeding groups. The results showed a slight reduction in diversity in the downstream segments, as well as along the longitudinal profile of the stream. However, there were no significant differences in abundance and richness between the upstream and downstream segments, indicating that the dams did not influence these variables. Differences were observed in the functional feeding groups along the longitudinal profile. Predator and gatherer insects were dominant in all segments analysed. The feeding group of shredders was more abundant in the segment DSIII with the participation of Marilia Müller (Odontoceridae – Trichoptera), although we observed a decrease of shredders and scrapers with the decrease of the canopy cover reducing values of β diversity in the continuum of Ribeirão das Anhumas. This result demonstrated the importance of the conservation of the riparian vegetation in order to maintain the integrity of the stream.