This study searched for a new pre-formulation based on the natural compound from the class of the avermectins, named abamectin (ABA), in order to improve its action against Aedes aegypti larvae by complexation with β-cyclodextrin (βCD). Concerning the low aqueous solubility of ABA, even in the presence of βCD, it was also invoked the strategy of working with hydrophobic nanoprecipitates (HNPs). For these purposes, molecular and supramolecular characterizations of 1:1 ABA/βCD complex and evaluation of its toxicity against A. aegypti larvae were performed. In the physical-chemistry characterizations, changes in the infrared spectra and thermal profiles in relation to precursors confirmed the occurrence of interactions between ABA and βCD in solid state. Nuclear magnetic resonance (NMR) data suggest the inclusion of ABA in βCD via benzofuran ring. Isothermal titration calorimetry (ITC) experiments allowed to verify the formation of complex with a 1:1 stoichiometry, which was entropy driven. The dynamic light scattering and zeta potential data from inclusion compounds demonstrated changes in the size of the ABA/βCD HNP if compared with the ABA HNP. Finally, the results for biological assays demonstrate that the strategy to prepare the inclusion compound led to an increase in the larvicidal activity in relation to free ABA.

The mosquito Aedes aegypti (Linnaeus, 1762) is the main vector of dengue and yellow fever viruses. Different methods have been used to control A. aegypti, including chemical and biological tools. However, chemical control can lead to a subsequent increase in the mosquitoes' insecticide resistance, and biological control represents an important method as an alternative to insecticide usage. Larvae from the Toxorhynchites genus (Diptera: Culicidae) are predators of other mosquitoes and represent a potential natural biocontrol agent of A. aegypti larvae. In the present work, A. aegypti larval survival was studied in the presence of the neotropical Toxorhynchites violaceus (Wiedemann, 1821) fourth instar larvae. Toxorhynchites violaceus consumption of A. aegypti increased during the 192 hours of the experiment and was more marked in the intervals between 96 and 120 hours and between 168 and 192 hours, when the A. aegypti survival reached 0%. During the fourth instar, T. violaceus increased its predation on A. aegypti larvae, possibly in order to increase its nutrient storage prior to pupation. Otherwise, low prey consumption can lead to a nutritional deficit for the larvae, delaying the adult's sexual development and reducing its egg production. Here we show that A. aegypti survival can be reduced by the T. violaceus fourth larvae predation under laboratory conditions

O presente estudo investigou as relações da força crítica (Fcrit) com o limiar de lactato (LL NA) e a intensidade de exercício correspondente ao VO2max (iVO2max) em nado atado (NA) e suas correlações com as performances de 400m (V400) e teste de 30 minutos (VT30) em nado livre (NL). Sete nadadores foram submetidos a teste incremental em NA para determinação do LL NA e da iVO2max. Para determinação da Fcrit, os nadadores realizaram 4 esforços até a exaustão com intensidades (F) correspondente a 87%, 104%, 118% e 134% da iVO2max para obtenção dos tempos limites (tlim). A Fcrit correspondeu ao coeficiente linear da relação entre a F e 1/tlim. Os valores de Fcrit (51,97 ± 4,02 N) foram significativamente diferentes da iVO2max (60,21 ± 8,73 N), mas não do LL NA (45,89 ± 8,73). A Fcrit foi significativamente correlacionada com o iVO2max (0,97), LL NA (0,88), V400 (0,85) e VT30 (0,86). Os resultados sugerem que a Fcrit pode ser utilizada na determinação da capacidade aeróbia, prescrição do treinamento em NA e na predição de performance em NL.

The present study investigated the relationship of critical force (Fcrit) with lactate threshold (LL NA) and the intensity corresponding to VO2max (iVO2max) in tethered swimming (TS), and their correlation with maximal performance in 400-m (V400) and 30-min (VT30) freestyle swimming (FS). Seven swimmers were submitted to a TS incremental test for the determination of LL NA and iVO2max. For the determination of Fcrit, the swimmers performed four exercises to exhaustion at intensities (F) corresponding to 87%, 104%, 118% and 134% of iVO2max for the calculation of time limits (Tlim). Fcrit corresponded to the linear coefficient of the ratio between F and 1/tlim. The maximal performance in FS corresponded to the mean velocity obtained during maximal exercise of 400-m and 30-min crawl swimming. Fcrit (51.97 ± 4.02 N) was significantly lower than iVO2max (60.21 ± 8.73 N) but not than LL NA (45.89 ± 8.73). Fcrit was significantly correlated with iVO2max (0.97), LL NA (0.88), V400 (0.85), and VT30 (0.86). These data suggest that Fcrit can be used for the determination of aerobic capacity, prescription of a TS training program, and prediction of performance in FS.