Variations in acaricidal effect of wettable sulfur on Tetranychus urticae (Acari:Tetranychidae): effect of temperature, humidity and life stage.
Under laboratory conditions, the acaricidal effect of wettable sulfur is influenced by climatic conditions and the stage of development of Tetranychus urticae. Its ovicidal effect results from the combined action of temperature and relative humidity (RH). Wettable sulfur becomes effective at 27.5 degrees C and 75% RH. Beyond this threshold, the acaricidal effect increases with rising temperature or humidity, to become complete at a temperature of 35 degrees C and 90% RH. Within the range of temperatures and humidities 20 degrees C/30% RH and 35 degrees C/90% RH the mortality of immatures (from protonymphs to teleiochrysalis) was total. Under similar experimental conditions, females usually died before the end of the experiment. Temperature and relative humidity increased the adulticidal potential of wettable sulfur. The fecundity of the sulfur-treated females and the viability of their progeny was found to depend on temperature and RH. According to the same climatic conditions, eggs were less susceptible than females, which were in turn less susceptible than juvenile stages.
Auger
Philippe
P
Institut National de la Recherche Agronomique, Ecole Nationale Supérieure Agronomique, Department of Ecology and Plant Protection, Laboratory of Acarology, 2, Place Pierre Viala, 34060 Montpellier cedex 01, France. auger@ensam.inra.fr
Guichou
Sabine
S
Kreiter
Serge
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D001681:Biological Assay; D005260:Female; D006813:Humidity; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D010063:Ovum / Q000187:drug effects; D013455:Sulfur / Q000494:pharmacology*; D013696:Temperature; D040102:Tetranychidae / Q000187:drug effects* / Q000254:growth & development*
D007306:Insecticides; D013455:Sulfur