Mobility of Organotin Pesticides: Azocyclotin And Cyhexatin In Clayey And Sandy Soils From The Northern Paraná State - Brazil

Azocyclotin and cyhexatin are pesticides commonly used in mite control. However, these organotin compounds are highly harmful to the aquatic ecosystem and supposedly mobile in the soil. In addition to not existing defined rules of use, few studies have been carried out on organotins' behavior and environmental control. Liquid chromatography has been pointed out for the OTC quantitation because of gas chromatography's thermal stability and derivatization limitations. Hence, a new high-performance liquid chromatography method with photodiode array detection (HPLC-PDA) was developed for quality assurance and quality control (QA/QC) and environmental performance assessment purposes. Hysteresis index (\emph{HI}) and mobilization factor were determined from sorption/desorption in sandy and clayey soils to assess mobility and environmental risk. Mobilization was observed for the two compounds by applying the dual-mode Freundlich-Langmuir model to the isotherms. Azocyclotin showed greater mobility, 23\% and 19\%, and \emph{HI} of $-$0.15 and 7.8$\times$10$^{-4}$ for clayey and sandy soil samples, respectively. Although cyhexatin was practically immobile for both soil samples, it can be mobilized as an azocyclotin metabolite, increasing the environmental impact and risk for agricultural uses.

Residual Tau-Fluvalinate in Honey Bee Colonies Is Coupled with Evidence for Selection for Varroa destructor Resistance to Pyrethroids

Varroa destructor is considered one of the most devastating parasites of the honey bee, Apis mellifera, and a major problem for the beekeeping industry. Currently, the main method to control Varroa mites is the application of drugs that contain different acaricides as active ingredients. The pyrethroid tau-fluvalinate is one of the acaricides most widely used in beekeeping due to its efficacy and low toxicity to bees. However, the intensive and repetitive application of this compound produces a selective pressure that, when maintained over time, contributes to the emergence of resistant mites in the honey bee colonies, compromising the acaricidal treatments efficacy. Here we studied the presence of tau-fluvalinate residues in hives and the evolution of genetic resistance to this acaricide in Varroa mites from honey bee colonies that received no pyrethroid treatment in the previous four years. Our data revealed the widespread and persistent tau-fluvalinate contamination of beeswax and beebread in hives, an overall increase of the pyrethroid resistance allele frequency and a generalized excess of resistant mites relative to Hardy–Weinberg equilibrium expectations. These results suggest that tau-fluvalinate contamination in the hives may seriously compromise the efficacy of pyrethroid-based mite control methods.

Parallel evolution of Varroa resistance in honey bees: a common mechanism across continents?

The near-globally distributed ecto-parasitic mite of the Apis mellifera honeybee, Varroa destructor, has formed a lethal association with Deformed wing virus, a once rare and benign RNA virus. In concert, the two have killed millions of wild and managed colonies, particularly across the Northern Hemisphere, forcing the need for regular acaricide application to ensure colony survival. However, despite the short association (in evolutionary terms), a small but increasing number of A. mellifera populations across the globe have been surviving many years without any mite control methods. This long-term survival, or Varroa resistance, is consistently associated with the same suite of traits (recapping, brood removal and reduced mite reproduction) irrespective of location. Here we conduct an analysis of data extracted from 60 papers to illustrate how these traits connect together to explain decades of mite resistance data. We have potentially a unified understanding of natural Varroa resistance that will help the global industry achieve widespread miticide-free beekeeping and indicate how different honeybee populations across four continents have resolved a recent threat using the same suite of behaviours.

Effect of Using Drone Brood Cells as Traps Against Varroa destructor (Varroa Mite)

Today, the honeybee parasite Varroa destructor is thought to be the most dangerous creature in the beekeeping industry worldwide. In this study, the efficacy of using drone brood cells (known to have no residue concerns in bee products and harmless on bee health) as traps against V. destructor was investigated. A total of 16 honeybee (Apis mellıfera) colonies with V. destructor infestation percentage of less than 5% were used for the trial. The treatment group consisted of 8 colonies that were randomly assigned to molded drone comb (comb with 5.4 mm hexagonal cells). The other 8 were assigned to unmolded comb to form the control group. In the trial groups, after 20 days (from 10th May), all drone combs with complete pupation were removed and destroyed on 30th May, 20th June, 10th July, 30th July, and 20th August. During the trial, varroa mite infestation rate (mean abundance), colony development, and varroa mite preference for drone and work bee brood cells were determined. The results showed that the application of drone brood cells as a control method was statistically significant against V. destructor, and did not negatively affect colony development. On the other hand, V.destructor's preference for both drone and worker bee brood cells among the groups was not statistically significant. In conclusion, drone brood cells ensured an approximately 43% success rate as traps against V. destructor compared to the control group. The effective application of drone brood cells as traps in combination with other Varroa mite control methods should be investigated.

Using Citizen Science to Scout Honey Bee Colonies that Naturally Survive Varroa destructor Infestations

Citizen Science contributes significantly to the conservation of biodiversity, but its application to honey bee research has remained minimal. Even though certain European honey bee (Apis mellifera) populations are known to naturally survive Varroa destructor infestations, it is unclear how widespread or common such populations are. Such colonies are highly valuable for investigating the mechanisms enabling colony survival, as well as for tracking the conservation status of free-living honey bees. Here, we use targeted Citizen Science to identify potentially new cases of managed or free-living A. mellifera populations that survive V. destructor without mite control strategies. In 2018, a survey containing 20 questions was developed, translated into 13 languages, and promoted at beekeeping conferences and online. After three years, 305 reports were collected from 28 countries: 241 from managed colonies and 64 from free-living colonies. The collected data suggest that there could be twice as many naturally surviving colonies worldwide than are currently known. Further, online and personal promotion seem to be key for successful recruitment of participants. Although the survivor status of these colonies still needs to be confirmed, the volume of reports and responses already illustrate how effectively Citizen Science can contribute to bee research by massively increasing generated data, broadening opportunities for comparative research, and fostering collaboration between scientists, beekeepers, and citizens. The success of this survey spurred the development of a more advanced Citizen Science platform, Honey Bee Watch, that will enable a more accurate reporting, confirmation, and monitoring of surviving colonies, and strengthen the ties between science, stakeholders, and citizens to foster the protection of both free-living and managed honey bees.

Residual Tau-Fluvalinate in Honey Bee Colonies is Coupled with Evidence for Selection for Varroa Destructor Resistance to Pyrethroids

Varroa destructor is considered one of the most devastating parasites of the honey bee, Apis mellifera, and a major problem for the beekeeping industry. Currently, the main method to control Varroa mites is the application of drugs that contain different acaricides as active ingredients. The pyrethroid tau-fluvalinate is one of the acaricides most widely used in beekeeping due to its efficacy and low toxicity to bees. However, the intensive and repetitive application of this compound produces a selective pressure that, when maintained over time, contributes to the emergence of resistant mites in the honey bee colonies, compromising the acaricidal treatments efficacy. Here we studied the presence of tau-fluvalinate residues in hives and the evolution of genetic resistance to this acaricide in Varroa mites from honeybee colonies that received no pyrethroid treatment in the previous four years. Our data revealed the widespread and persistent tau-fluvalinate contamination of beeswax and beebread in hives, an overall increase of the pyrethroid resistance allele frequency and a generalized excess of resistant mites relative to Hardy-Weinberg equilibrium expectations. These results suggest that tau-fluvalinate contamination of the hives may seriously compromise the efficacy of pyrethroid-based mite control methods.

Lithium chloride outperformed oxalic acid sublimation in a preliminary experiment for Varroa mite control in pre-wintering honey bee colonies

Since lithium salts were demonstrated to be very effective for the potential control of Varroa destructor, a highly detrimental parasite of honey bee (Apis mellifera), no studies have been reported on their comparison with any commonly used varroicides in commercial bee colonies. In this study we compared the effectiveness of lithium chloride to that of oxalic acid, a widely used miticide. The results of the present study confirm that lithium has superior efficacy to oxalic acid sublimation both as a main or a supplementary pre-wintering treatment at moderate infestation levels, restricted to certain pre-wintering conditions. Considering its easy implementation in apicultural practice and its twofold mode of action, trickling would be the preferred way of administration after the use of lithium salts as varroicides is authorised.

Mange skin diseases in dogs and cats in Jataí, Brazil: A retrospective study with notes on zoonotic aspects

The parasitic skin diseases, specifically mange diseases, are highly relevant in the animal health studies, due to a significant number of cases in the veterinary routine, beyond the importance in public health, due to zoonotic potential. Therefore, this study aimed report the occurrence of mange skin diseases with notes in the zoonotic potential from Jataí, Goiás, by an retrospective survey of mange cases diagnosed in dogs and cats treated at the Veterinary Hospital of the Federal University of Jataí. A total of 612 reports of parasitological tests, comprising cerumen swabs and skin scraping, were analyzed from January 2016 to December 2019. The most common causative mite in dogs was Demodex canis (10.94%), followed by Otodectes cynotis (2.92%), and Sarcoptes scabiei (2.54%). The most common causative mite in cats was Notoedres cati (20%), followed by O. cynotis (10%). These skin diseases are characterized as being highly contagious; therefore, these can be easily transmitted among animals and even humans. In addition, intense itching and skin lesions lead to discomfort, consequently causing stress to the animals. Thus, mite control as well as prompt diagnosis and treatment are relevant to manage these skin diseases and ensure animal welfare.

Formulation of nanopesticide with graphene oxide as the nanocarrier of pyrethroid pesticide and its application in spider mite control

Nanopesticides with controlled release can achieve more effective utilization of pesticides.

A salivary chitinase of Varroa destructor influences host immunity and mite’s survival

Varroa destructor is an ectoparasite of honey bees and an active disease vector, which represents one of the most severe threats for the beekeeping industry. This parasitic mite feeds on the host’s body fluids through a wound in the cuticle, which allows food uptake by the mother mite and its progeny, offering a potential route of entrance for infecting microorganisms. Mite feeding is associated with saliva injection, whose role is still largely unknown. Here we try to fill this gap by identifying putative host regulation factors present in the saliva of V. destructor and performing a functional analysis for one of them, a chitinase (Vd-CHIsal) phylogenetically related to chitinases present in parasitic and predatory arthropods, which shows a specific and very high level of expression in the mite’s salivary glands. Vd-CHIsal is essential for effective mite feeding and survival, since it is apparently involved both in maintaining the feeding wound open and in preventing host infection by opportunistic pathogens. Our results show the important role in the modulation of mite-honey bee interactions exerted by a host regulation factor shared by different evolutionary lineages of parasitic arthropods. We predict that the functional characterization of Varroa sialome will provide new background knowledge on parasitism evolution in arthropods and the opportunity to develop new bioinspired strategies for mite control based on the disruption of their complex interactions with a living food source.