Varroa destructor is an ectoparasitic mite causing devastating damages to honey bee colonies around the world. Its impact is considered a major factor contributing to the significant seasonal losses of colonies recorded every year. Beekeepers usually rely on a reduced set of acaricides to manage the parasite, usually the pyrethroids tau-fluvalinate or flumethrin, the organophosphate coumaphos, and the formamidine amitraz. However, the evolution of resistance in the mite populations is leading to an unsustainable scenario with almost no alternatives to reach an adequate control of the mite. Here, we present the results from the first large-scale and extensive monitoring of the susceptibility to acaricides in the Comunitat Valenciana, one of the most prominent apicultural regions in Spain. Our ultimate goal is to provide beekeepers with timely information to help them decide what would be the best alternative for a long-term control of the mites in their apiaries. Our data show that there is a significant variation in the expected efficacy of coumaphos and pyrethroids across the region, indicating the presence of a different ratio of resistant individuals to these acaricides in each population. On the other hand, the expected efficacy of amitraz was more consistent, though slightly below the expected efficacy according to the label.

BACKGROUND: Managed honey bees are key pollinators of many crops and play an essential role in the United States food production. For more than ten years, beekeepers in the United States have been reporting high rates of colony losses. One of the drivers of these losses is the parasitic mite Varroa destructor. Maintaining healthy honey bee colonies in the United States is dependent on a successful control of this mite. The pyrethroid tau-fluvalinate (Apistan®) was among the first synthetic varroacides registered in the United States. With over 20 years of use, mites resistant to Apistan® have emerged, and so it is unsurprising that treatment failures have been reported. Resistance to tau-fluvalinate in US mite populations is associated with point mutations at position 925 of the voltage-gated sodium channel.RESULTS: Here, we have generated a distribution map of pyrethroid resistance alleles in Varroa samples collected from US apiaries in 2016 and 2017, using a high throughput allelic discrimination assay based on TaqMan®. Our results evidence that knockdown resistance (kdr)-type mutations are widely distributed in Varroa populations across the country showing high variability among apiaries. We used these data to predict the phenotype of the mites in the case of treatments with pyrethroids. CONCLUSION: We highlight the relevance of monitoring the resistance in mite populations to achieve an efficient control of this pest. We also put forward the benefits of implementing this methodology to provide data for designing pest management programs aiming to control Varroa.

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Endemic species tend to be habitat specialists with low population densities, but densities may vary among sites and may be temporally dynamic. In addition, species may exhibit plasticity in habitat use, with the result that densities vary in different habitats. The Cauca Guan (Penelope perspicax) is an endangered species endemic to the mid-Cauca Valley in Colombia. To assess spatial variation in population densities, we surveyed different habitat types (mature and secondary forest, early regeneration, and vegetation strips along streams) in three sites and compared them to densities reported in previous studies to explore possible changes over a period of several years. At the three sites, densities varied between 10 and 40 birds/km 2 in different habitats. Variation in population density may be related to forest area and habitat productivity, but guans are known to move among locales and regions in response to temporal fluctuations in resource availability. Cauca Guan densities are comparable to those of other montane Penelopine guans with broader geographic distributions. Although the Cauca Guan is not a habitat specialist and may reach high densities under some conditions, globally this guan remains rare and efforts for its conservation should be sustained.Key words: Cracidae, Colombia, endangered species, endemicity, population density Resumen Las especies endémicas tienden ser especialistas de hábitat con bajas densidades poblacionales, pero las densidades pueden variar entre sitios y en el tiempo. Las densidades también pueden variar entre tipos de hábitat. La pava caucana (Penelope perspicax) es una especie amenazada, endémica del valle medio del río Cauca en Colombia. Para evaluar la variación espacial de las densidades poblacionales, hicimos muestreos en diferentes tipos de hábitat (bosques maduros y secundarios, regeneración temprana y bandas de vegetación a lo largo de quebradas) en tres sitios y comparamos las densidades con aquellas reportadas en estudios previos, para determinar si hay cambios temporales. En los tres sitios las densidades variaron entre 10 y 40 individuos/km 2 en los diferentes hábitats. Las variaciones en la densidad poblacional pueden estar relacionadas con el área de bosque y la productividad del hábitat, pero las pavas también hacen movimientos locales y regionales en respuesta a las fluctuaciones temporales en la disponibilidad de recursos. Las densidades de la pava caucana son similares a las reportadas para otras especies de Penelopinae de montaña con distribuciones geográficas más amplias. Aunque la pava caucana no es especialista de hábitat y puede alcanzar altas densidades bajo ciertas condiciones, globalmente es una especie rara y deben mantenerse los esfuerzos para su conservación.