Effect of temperature and humidity on the pulicidal activity of an opoka dust (opaline silica) under laboratory experimental conditions
Mironov, A.N.
Meditsinskaia Parazitologiia i Parazitarnye Bolezni 60(1): 41-44
1981
ISSN/ISBN: 0025-8326 PMID: 6259504 Document Number: 179132
The factors that influence the effectiveness of dust as a means of controlling fleas in rodent burrows were investigated experimentally in the laboratory. In a preliminary study, the most promising materials were found to be certain forms of opaline silica (diatomite, opoka and tripoli). Opoka from mountain rock, with a particle size of 1-250 mu m, was tested on unfed males and females of Nosopsyllus fasciatus (Bosc) (Ceratophyllus fasciatus) at temperatures ranging from 5-10 to 28-29 deg C and relative humidity from 43 plus or minus 2 to 98 plus or minus 2%. These conditions covered the range found in the upper parts (30-50 cm deep) of colony burrows of the great gerbil (Rhombomys opimus) in the warm months of the year. One group of fleas was exposed to the dust for 60 min, while another was exposed continuously until they all died. The dust proved effective at all combinations of temperature and relative humidity, but the time required for death to occur varied with the regime. The fleas were sluggish at 5-10 deg C and most active at 28-29 deg C, and when kept at the latter temperature died much sooner at 43 plus or minus 2% RH than at 98 plus or minus 2% RH. At the highest relative humidity, the effectiveness of the dust was reduced by adsorption. In the gerbil burrows, the conditions of high temperature and low atmospheric humidity most favourable for the effectiveness of dust occur between July and October.