Repellency of a kaolin particle film, Surround, and a mineral oil, Sunspray oil, to silverleaf whitefly (Homoptera: Aleyrodidae) on melon in the laboratory.

Abstract

Surround, a kaolin-based particle film formulation, and Sunspray oil, a mineral oil, were evaluated alone or in combination in choice and no-choice laboratory assays on melon leaves for repellency to adults of the silverleaf whitefly, Bemisia argentifolii Bellows & Perring. In no-choice tests, the number of adults and eggs on leaves did not significantly differ among the three treatments and the water control when materials were applied to either the tipper or lower leaf surface. Significantly fewer adults and eggs were found on treated leaves compared with water when materials were applied to both leaf surfaces. Application of Surround did not affect the oviposition pattern, with 80.2-88.5% eggs oviposited on lower surface. However, whiteflies oviposited more eggs (53.1-63.8%) on the upper compared with the lower surface when Sunspray oil or Surround + Sunspray oil was applied on the lower leaf surface and both leaf surfaces. When whiteflies were allowed to choose among leaves treated with different materials on the same leaf surface(s), significantly fewer adults and eggs were found on treated leaves compared with water-treated leaves, and more adults and eggs were found on leaves when the materials were applied to tipper versus lower or both surfaces. Leaves treated with materials on both leaf surfaces had fewer whiteflies compared with leaves treated on the upper or lower surface. When whiteflies were allowed to choose among leaves treated with materials versus water-treated leaves in a 6:3 or an 8:1 ratio, significantly fewer adults and eggs were found on leaves treated with treatment materials compared with water, regardless of which leaf surface(s) were treated. No significant synergistic or additive effect was detected in Surround + Sunspray oil compared with either material used separately.