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).

Metarhizium anisopliae Metchnikoff (Hypocreales: Clavicipitaceae) is a fungal pathogen that causes disease in various insect pests, and it can be exploited and developed as a biological control agent to combat the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae). The study on indigenous isolates is crucial especially for development of bioinsecticides in the future. The M. anisopliae strain called MET-GRA4 was tested for pathogenicity against adult red palm weevil and treated in vitro with different spore viabilities. The isolates exhibited pathogenicity with 100% mortality 21 d postinfection. The median lethal time (LT50) for 85% viable spores was 8.6 d, while 39% viable spores had an LT50 value of 21.37 d, with 92 and 16.6% mycosis, respectively. The species MET-GRA4 strain was molecularly characterized using ITS1 and ITS4 from pure culture (Isolate A), mass-produced spores (Isolate B), and infected red palm weevil cadavers (Isolate C). The DNA sequences obtained matched M. anisopliae sequences, with 99% similarity. This new isolate of M. anisopliae has potential as a targeted bioinsecticide for management of red palm weevil.

Elaeidobius kamerunicus is the main insect pollinator for oil palm (Elaeis guineensis) worldwide. One of the main reasons E. kamerunicus attracted to oil palm inflorescences is estragole, a volatile organic compound released by the oil palm inflorescences during anthesis stage. However, the amount of estragole released from the oil palm inflorescence is varied due to the influence of abiotic and biotic factors and is seen to have an impact on E. kamerunicus pollination activity on the oil palm. To evaluate the responses of E. kamerunicus, different types (wild and reared) and sex (male and female) of E. kamerunicus were exposed to different concentrations of commercial estragole using a four-arm olfactometer. Results showed that E. kamerunicus significantly preferred one hundred ppm of estragole compared to other concentrations. However, the response of E. kamerunicus was significantly decreased after the concentration value. The result of this study can be a good platform for future references since the estragole compound plays a significant role in oil palms flower pollination by E. kamerunicus.