Publikationsdatenbank

Occurrence and distribution of insecticide resistance in stable flies (Stomoxys calcitrans) on dairy farms in the Federal State of Brandenburg, Germany (2018)

Art

Hochschulschrift

Autor

Reissert, Sophia (WE 13)

Quelle

Berlin: Mensch und Buch Verlag Berlin, 2018 — IX, 131 Seiten

ISBN: 978-3-86387-940-2

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/23638

Kontakt

Institut für Parasitologie und Tropenveterinärmedizin

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 62310
parasitologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Stable flies (Stomoxys calcitrans) are a common problem in animal husbandry worldwide. Nuisance, especially by biting flies, can have a considerable negative impact on animal well-being, health and productivity. Furthermore, stable flies are known vectors of a range of pathogens. Insecticides constitute the mainstay for their control. However, if insecticides are applied in a non-strategic manner, there are risks of developing insecticide resistance within a few generations due to the high reproductive rate of stable flies. The objective of this study was to assess the occurrence of insecticide resistance in Stomoxys calcitrans on dairy farms in Brandenburg, Germany. Moreover, it aspired to propose best-bet strategies for on-farm pest control aiming to minimize the use of insecticides. Based on a telephone questionnaire survey performed in June 2015 with 52 dairy farms in Brandenburg, 40 farms were selected for an on-farm cross-sectional survey. In this survey the FlyBox®-method was used in order to evaluate the susceptibility of stable flies to a deltamethrin impregnated polyester fabric. For confirmatory evaluation, Stomoxys populations from 10 farms were caught and colonies established in the laboratory. The susceptibility of the emerging F1 to F3 generations was tested with current methods under controlled conditions. In a first step, the LD95 of deltamethrin and azamethiphos were defined with established sensitive laboratory strains of S. calcitrans. Then the toxicity of both was assessed by topical application of the LD95 and multiples of it. The larvicidal effects of two insect growth regulators, cyromazine and pyriproxyfen, were evaluated at different concentrations based on the manufacturers’ recommendations. The questionnaire survey revealed that pyrethroids are the most frequently used insecticides (78.9 %) with deltamethrin being the dominant active ingredient (41 %). Furthermore, the on-farm survey using the FlyBox®-method indicated deltamethrin resistance in all of the 40 tested strains (100 %). In the laboratory tests, 24 hours following topical application of deltamethrin and azamethiphos to all of the 10 strains using the LD95 of 2.3 and 4.9 ng/fly, respectively, mortalities below 90 % were encountered. This led to the conclusion that these populations were resistant to the tested insecticides. Nine out of the 10 populations (90 %) even showed a mortality below 40 % at the LD95 of both deltamethrin and azamethiphos. Forty to 80 % of the mortality rates of multiples of the LD95 of azamethiphos and deltamethrin, respectively, were below 90 %. The insect growth regulators cyromazine and pyriproxyfen tested at the recommended concentrations resulted in an inhibition rate of 100 % of all 10 populations. The study revealed that there is an urgent need to conduct further field surveys in different livestock production systems in order to draw general conclusions concerning the resistance status in Germany and the EU. Those studies would facilitate the elaboration of better integrated pest management strategies in order to warrant the use of insecticides as a last resort only within a given cascade of possible control measures. This would sensitise farmers as well as veterinarians on resistance development and its impact on the environment. The design of genetic markers for the detection of insecticide resistance should be promoted in order to simplify further testing. In conclusion, the legal regulation of some insecticides should be evaluated regularly protecting human health and preventing negative impacts on honey bees, hymenoptera and other non-target insects.