Summary

Coconut is a major livelihood crop of many Sri Lankans, a raw material of many industries and a source of foreign income generation. Coconut mite, Aceria guerreronis Keifer is one of the major pests of coconut in Sri Lanka causing severe losses in the affected areas. A total estimated crop loss of 15.8% has been reported due to the coconut mite damage in Sri Lanka. At the outset of the infestation in Sri Lanka, many chemicals have been tested and a few of them have been recommended to control the pest. Recently, a biological control method using the predatory mite, Neoseiulus baraki has also been recommended. Nevertheless, use of resistant/tolerant coconut varieties has been identified as a practical, eco-friendly and the most sustainable approach to manage the pest in Sri Lanka. Differences in the susceptibility of the coconut varieties to the coconut mite have been observed and detailed research is necessary to identify the underlying mechanisms of resistance/tolerance of the host plants.

In this project, it is intended to understand the searching behavior, survival and reproduction of coconut mites in relation to resistant/tolerant and susceptible coconut varieties and to identify differences in lipid profiles, phenolic compounds and volatile organic compounds in resistant/tolerant and susceptible coconut varieties to the coconut mite damage.

Searching behavior of coconut mites and N. baraki on different varieties will be tested in release-recapture experiments with starved adult female mites on a cross-shaped runway arena. Percent survival and reproduction success of coconut mites will be tested on discs of meristematic region of the coconut fruits of different varieties. Volatile organic compounds and methylated low polar fractions of lipids will be analyzed using GC-MS while phenolic rich methanol fractions will be subjected to HPLC analysis.

Objectives

i. To understand the searching behaviour, survival and reproduction of coconut mites in relation to resistant and susceptible coconut varieties.

ii. To determine volatile organic compound (VOC) profiles of coconut varieties with different susceptibility levels to the coconut mite.

iii. To identify the changes in VOC profiles of different coconut varieties with the coconut mite infestation.

iv. To compare lipid profiles and phenolic compounds of the epidermis in the meristematic region of the coconut fruits of varieties with different susceptibility levels to the coconut mite, prior and after the infestation of coconut mite.