Effect of leaf lamina colour on the behavioral characteristics of Deltocephalus menoni (Hemiptera: Cicadellidae); A vector of sugarcane white leaf disease

Abstract

Deltocephalus menoni is the only locally- identified vector of Sugarcane White Leaf Disease (WLD) in Sri Lanka. Leaf lamina colour of sugarcane plants is one of the major characteristics that effects on approach and arrest of the vector during initial colonization. Differences in population levels of D. menoni have been recorded in sugarcane fields which were maintained in a similar manner with different varieties of same age. This study conducted at the Entomology Laboratory of the Sugarcane Research Institute (SRI), Uda Walawe aimed to detect the effect ofleaf lamina colour of sugarcane varieties on the behavioral characteristics of D. menoni. Leaf lamina colour of ten sugarcane verities and behavioral characteristicsof D. menoni on these varieties were studied. Pearson correlation coefficient test was performed to detect the associationsexisting between leaf lamina colour and insect behavioral characteristics Red colour had significant and negative correlations with the aggregation, amount of feeding, rate of nymphs convert into adult and adult longevity but not withthe nymphal period and oviposition. The green colour had significant and negative correlations with the amount of feeding and adult longevity of D.menonibut not with rate of nymphs convert into adult, nymphal period and oviposition. No significant correlations were found between behavioral characteristics of D. menoni and blue color intensity, hue, overall leaf colour saturation and brightness of the leaves. Results imply that higherintensities of red and green colour compositions in leaf lamina cause for making the plant less attractive for aggregation, insect feeding, nymphal period and adult longevity of D. menoni.