The effect of artificial substrates on the pathogenicity of Steinernema feltiae (Rhabditida: Steinernematidae) to adult Musca domestica (Diptera: Muscidae)

Abstract

Effects of some artificial substrates on the ability of the entomopathogenic nematode Steinernema feltiae to kill adult Musca domestica were studied. Replicate samples of different substrates were treated with known numbers of S. feltiae suspended in 0.25 M sucrose. Then 30 adult female flies were confined above each sample in a crystalizing basin and mortality counts were carried out 48 h later. The most effective substrates were poplin cotton, potting compost, silver sand and Fibertex SF250 horticultural capillary matting, which gave LD50 in the range of 2815 to 8912 S. feltiae. Conversely, Perlite was the least efficient material and required between 531 450 and 899 930 S. feltiae to achieve the LD50. These effects appeared to be related to the total porosity (ratio of the volume of air spaces in each material to its bulk volume) of each material, with the most efficient materials having total porosities in a median range of between 0.81 and 0.14. The significance of these observations is discussed. Les effets de certains substrats artificiels sur l’aptitude du nématode entomopathogène Steinernema feltiae à tuer les adultes de Musca domestica ont été étudiés. Des sérics d’échantillons de différents substrats ont été traitées avec des nombres connus de S. feltiae en suspension dans une solution de saccharose 0,25 M. Trente mouches femelles adultes ont été ensuite enfermées au-dessus de chaque échantillon, dans un cristallisoir, et des dénombrements de mortalité effectués 48 h plus tard. Les substrats les plus efficaces ont été la popeline de coton, le terreau de rempotage, le sable micacé et le Fibertex SF250, une natte capillaire horticole, qui ont permis d’atteindre la LD50 dans la fourchette de 2815 à 8912 S. feltiae. Par contre, la Perlite s’est révélée le matériau le moins efficace, et il a fallu entre 531 450 et 899 930 S. feltiae pour atteindre la LD50. Ces effets semblent liés à la porosité totale (rapport entre le volume des espaces remplis d’air dans chaque matériau et son volume en vrac) des matériaux, celle des plus efficaces étant située dans une fourchette médiane de 0,81 et 0,14. L’importance de ces observations est discutée.

Application and evaluation of entomopathogens for control of livestock and poultry pests

“…Other types of animal manure also generally are not as nitrogen-rich as that of poultry, and the entomopathogenic nematodes may have better prospects there. If used in a bait station type approach, the porosity of substrate can have substantial effects on how well flies may be infected by such nematodes; cotton poplin was good, while Perlite was poor, for example (Renn and Wright, 2000).…”

7. Prevention and control of tick-borne anaplasmosis, cowdriosis and babesiosis in the cattle industry

“…In contrast, mortality was <70% when flies were housed with pads moistened with an EPN-based suspension in 5% sucrose, even at the high rate of 100,000 EPN per ml of bait. Renn and Wright (2000) found that EPN delivery in a 0.25 M sucrose solution to adult flies varied depending on the type of substrate on which the bait was presented. For example, the lethal dose to 50% mortality (LD 50 ) for S. feltiae was about 200 times lower on cotton poplin than on perlite.…”