Effect of the epicuticular wax level of leaf lamina on the behaviour of leaf hopper &lt;em&gt;Deltocephalus menoni&lt;/em&gt; (Hemiptera: Cicadellidae); A vector of sugarcane white leaf disease

K M G Chanchala,V K A S M Wanasinghe,W R G Witharama,K S Hemachandra,L Nugaliyadde

doi:10.4038/tar.v31i1.8345

Effect of the epicuticular wax level of leaf lamina on the behaviour of leaf hopper <em>Deltocephalus menoni</em> (Hemiptera: Cicadellidae); A vector of sugarcane white leaf disease

K M G Chanchala, V K A S M Wanasinghe + Show 3 more

Open Access

https://doi.org/10.4038/tar.v31i1.8345

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Abstract

Sugarcane White Leaf Disease (WLD) is one of the major threats to the cane sugar industry in Sri Lanka and Deltocephalus menoni is the only recorded vector in local conditions. Epicuticular waxes (EW) play an important role in protecting plants against herbivore attacks. Therefore, this study was conducted with the objective of determining the effect of EW level on the behavioral characteristics of D. menoni in ten different sugarcane varieties. EW level of the selected varieties, behavioral characteristics of D. menoni and the level of WLD infection under natural conditions were studied. The effect of surface waxes on feeding behavior of D. menoni was also investigated under in-vitro conditions using agarosesucrose. Pearson correlation coefficient test was performed to detect the associations between EW and insect behavioral characteristics. Varieties with higher level of EW showed a significantly lower D. menoni feeding and disease infection. There was a significantly positive correlation (r = 0.78, P = <0.0001) between the level of feeding and rate of disease infection in natural environment. Hence it is quite possible that wax may play a significant role in feeding of D. menoni on sugarcane. In vitro study also further confirmed the relationship of EW and feeding behaviour by recording high feeding preference in agarose-sucrose diet containers with less wax content. Therefore, sugarcane accessions having high level of EW could be incorporated into directional breeding of varieties to increase the resistance against WLD.

Highlights

Sugarcane White Leaf Disease (WLD) is one of the major threats to the cane sugar industry in Sri Lanka and Deltocephalus menoni (Hemiptera: Cicadellidae, Deltocephalinae) is the only local vector, as identified to date, which is capable of transmitting this phytoplasma disease (Senevirathne, 2008)
Variation of leaf laminar wax among sugarcane varieties that has variable resistance to WLD The amount of wax extracted from leaf lamina had a significant (P=0.05) variation among the tested sugarcane varieties
Varieties/ accessions with a higher level of leaf lamina epicuticle wax of sugarcane leaves caused a significant reduction of the D. menoni feeding on leaves and level of disease infection

Summary

Introduction

Sugarcane White Leaf Disease (WLD) is one of the major threats to the cane sugar industry in Sri Lanka and Deltocephalus menoni (Hemiptera: Cicadellidae, Deltocephalinae) is the only local vector, as identified to date, which is capable of transmitting this phytoplasma disease (Senevirathne, 2008). Management of WLD vector has been identified as a strategic and integrated approach to prevent the rapid spread of WLD disease in sugarcane plantations. In this context, the breeding of plants that are either resistant or deter the behavioural characteristics of vector would be a first line of defense to manage the WLD. In Sri Lanka, screening of sugarcane germplasm for WLD resistance is continuing using conventional screening methods under the natural infection of the WLD. In this breeding programme, 66 tolerant sugarcane varieties and 20 moderately tolerant sugarcane varieties for WLD have been identified

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