Physical and Physiological Monitoring on Red Palm Weevil-Infested Oil Palms.

Nazmi Harith-Fadzilah,Maizom Hassan,Azlina Zakaria,Samsudin Amit,Wahizatul Afzan Azmi,Johari Jalinas,Mohamad Haris-Hussain,Idris Abd Ghani,Zamri Zainal

doi:10.3390/insects11070407

Nazmi Harith-Fadzilah, Maizom Hassan + Show 7 more

Open Access

https://doi.org/10.3390/insects11070407

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Abstract

The red palm weevil (RPW) is a stem boring Coleoptera that decimates host palm trees from within. The challenge of managing this pest is due to a lack of physical symptoms during the early stages of infestation. Investigating the physiological changes that occur within RPW-infested palm trees may be useful in establishing a new approach in RPW detection. In this study, the effects of RPW infestation were investigated in Elaeis guineensis by observing changes in physical and physiological parameters during the progress of infestation by visual inspection and the comparison of growth, gas exchange, stomatal conductance, and chlorophyll content between the non-infested control, physically wounded, and RPW-infested E. guineensis groups. During the study period, four distinct levels of physical infestation were observed and recorded. The RPW-infested group displayed significantly lower maximum photosynthesis activity (Amax) starting from the third week post-infestation. However, growth in terms of change in plant height and stem circumference, leaves’ stomatal conductance, and chlorophyll content were not significantly different between the three groups during the duration of the study. The significant drop in photosynthesis was observed one week before physical changes appeared. This suggests the promising utilisation of photosynthesis activity as a signal for detecting RPW infestation at the early stage of attacks, which could be useful for integration in integrated pest management (IPM).

Highlights

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), is a destructive and invasive stem-boring pest affecting the majority of palm species worldwide
Adult RPWs were sampled by the Terengganu Department of Agriculture from heavily-infested coconut plantations in Terengganu by using specific pheromone lures (4-methyl-5-nonanol) and pheromone traps [1,16,17]
During Level 1 infestation, there were no visual symptoms of attack by the RPW larvae observed on the infested E. guineensis group (Figure 1A,B)

Summary

Introduction

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), is a destructive and invasive stem-boring pest affecting the majority of palm species worldwide. In the South East Asian region, cases of RPW infestation have been reported in Thailand, Malaysia, Indonesia, the Philippines, India, and Sri Lanka where economically important palm species such as coconut (Cocos nucifera) and oil palm (Elaeis guineensis), as well as ornamental palms such as ribbon fan palm and Chinese fan palm, are affected [2]. Insects 2020, 11, 407 and crevices of the soft tissue of the palm, primarily at the crown of the host palm [3,4,5]. It is difficult to identify infested palm trees in palm plantations due to the lack of obvious symptoms of infestation, especially at the early stage of infestation. As the infestation becomes more severe, physical signs become more apparent [6]

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