Coconut Leaf Age and Coconut Rhinoceros Beetle Herbivory Influence Leaflet Nutrients, Metals, and Lignin

Thomas Marler

doi:10.3390/horticulturae4020009

Abstract

The coconut rhinoceros beetle (CRB, Oryctes rhinoceros L.) is a serious pest of coconut (Cocos nucifera L.) in many tropical regions, however the influences of CRB herbivory on the coconut leaf chemistry are unknown. This limits our ability to predict the afterlife decomposition dynamics of the damaged coconut leaf litter. Mature green and senesced leaflet tissues were collected from coconut trees on the island of Guam, where coconut is native and CRB is invasive. Mineral, metal, and lignin concentrations were quantified to determine the nutrient limitations and the litter quality traits. Nitrogen was increased and the elements that are not resorbed during leaf senescence were decreased by the CRB damage. The important litter stoichiometric traits carbon/nitrogen and lignin/nitrogen were decreased by the CRB damage. The results indicate that CRB herbivory may limit green leaf nutrition in Guam’s soils and increase the senesced leaf litter decomposition speed and nutrient turnover rates.

Highlights

The pantropical coconut (Cocos nucifera L.) is a palm tree that provides all of the necessities of life [1,2]
Leaf age and coconut rhinoceros rhinoceros beetle beetle (CRB) damage did not interact for the macronutrients that were resorbed during leaf senescence
All of the nutrients that exhibited a significant interaction between leaf age and CRB herbivory (Table 2) revealed the same pattern

Summary

Introduction

The pantropical coconut (Cocos nucifera L.) is a palm tree that provides all of the necessities of life [1,2]. The buoyant fruits lead to the hydrochory of seeds, which enables long distance oceanic dispersal, and means that the islands throughout Oceania possess high density coconut tree populations. In tropical island nations with widespread agroforests, the coconut is almost always a prominent component of the emergent canopy. Under these settings, horticultural care is provided, but few or no fertilizer inputs are included in the agroforest management. An understanding of nutrient turnover is needed to sustainably manage these agroforests. The coconut rhinoceros beetle (Oryctes rhinoceros L., Coleoptera: Scarabaeidae) is native to the

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Conclusion