Influence of temperature and relative humidity on the efficacy of diatomaceous earth and Metarhizium anisopliae (Metschinkoff) Sorokin (Hyphomycetes: Deuteromycotina) against Tyrophagus fatimii F. (Astigmata: Acaridae)

  • W. Wakil Department of Agricultural Entomology, University of Agriculture, Faisalabad, Pakistan. Email: waqaswakeel@hotmail.com
  • M. U. Ghazanfar Plant Pathology, College of Agriculture, D.G. Khan, Sub-Campus University of Agriculture, Faisalabad, Pakistan
  • F. Mustafa Department of Agricultural Entomology, University of Agriculture, Faisalabad, Pakistan

Abstract

The combined as well as the alone effect of diatomaceous earth (DE) and entomopathogenic fungi were evaluated against Tyrophagus fatimii (Astigmata: Acaridae). Two different dose rates of DE (1 g and 1.5 g/kg of wheat) and three of the fungus Metarhizium anisopliae (Hyphomycetes: Deuteromycotina) (3.6 x 107, 3.6 x 108 and 3.6 x 109 conidia/kg of wheat) were taken and studied at 20°C and 25°C with 45% and 55% r.h. under three exposure intervals. It was found that the combined effect of DE diatomaceous earth and M. anisopliae was maximum at 25°C and 55% r.h. which gave 75% adult mortality at their highest dose rates, however, DE alone exhibited the highest mortality (61.3%) at 25°C and 45% r.h. On the other hand, M. anisopliae gave maximum mortality of mites (48.7%) at 20°C and 55% r.h. at 3.6 x 109 conidia/kg of wheat. It was concluded that the efficacy of both DE and M. anisopliae increased with the increase of the exposure interval. Moreover, the increase of dose increased the mortality. In addition, temperature and r.h. are the key factors for determining the effectiveness of both DE and M. anisopliae.

Keywords: Diatomaceous earth, Tyrophagus fatimii, Metarhizium anisopliae, Stored wheat.
Veröffentlicht
2010-09-20
Rubrik
Section: Residual Insecticides - Synthetic and Botanical