Pyrethroid and organophosphate pesticide resistance in field populations of horn fly in Brazil.

Pesticides are used worldwide to control arthropod parasites in cattle herds. The indiscriminate and/or inappropriate use of pesticides without veterinary guidance is a reality in several countries of South America. Improper pesticide use increases the chances of contamination of food and the environment with chemical pesticides and their metabolites. Reduction of these contamination events is an increasing challenge for those involved in livestock production. The horn fly, Haematobia irritans (Linnaeus) (Diptera: Muscidae), is one of the most economically important parasites affecting cattle herds around the world. As such, horn fly control efforts are often required to promote the best productive performance of herds. Pesticide susceptibility bioassays revealed that pyrethroid resistance was widespread and reached high levels in horn fly populations in the Brazilian state of Rondônia. The knockdown resistance (kdr) sodium channel gene mutation was detected in all horn fly populations studied (n = 48), and the super kdr sodium channel gene mutation was found in all homozygous resistant kdr individuals (n = 204). Organophosphate resistance was not identified in any of the fly populations evaluated.

Effects of ENSO events on the intensity, seasonality, and diversity of reproductive phenology of Miconia (Melastomataceae) species in tropical rainforest.

We evaluated the phenology and reproductive phenological diversity of three sympatric species of Miconia in a gallery forest in the Chapada Diamantina mountains, Bahia, Brazil. The reproductive phenophases (bud, flower, immature fruit, and mature fruit) of M. alborufescens (N=38), M. holosericea (N=46), and M. prasina (N=44) were evaluated monthly, between June/2008 and June/2015. The Fournier index was used to assess the intensities of the reproductive phenophases; synchrony and seasonality were analyzed using circular statistics and the Rayleigh (Z) test. The Frideman and Wilcoxon tests were used to verify interannual variations in phenological patterns. Reproductive phenological diversity was measured by calculating the Shannon-Wiener index; ANOVA tested possible differences in the means of diversity among the different years. The reproductive phenophases of the studied Miconia species occurred sequentially (M. alborufescens, then M. holoserica, followed by M. prasina), in the transition between the dry and rainy seasons, with little overlap between them. In general, the species showed seasonal and synchronic phenological patterns, with some variations that coincided with El Niño and/or La Niña events, e.g., demonstrating changes in the periodicity, synchrony, and intensity of their phenophases. The intensity of fruiting, for example, showed increases during La Niña years. Reproductive phenological diversity appears to respond to climate changes resulting from El Niño events and periods of prolonged drought, with high Shannon-Wiener index values. The results also suggest that the effects of global climatic phenomena (El Niño and La Niña) that alter regional climatic seasonality can also cause variations in the reproductive phenological rhythms of the Miconia species studied.