Effect of spikelet position and soil type on the population density of Elaeidobius kamerunicus in anthesising oil palm male inflorescence

In Malaysia, poor oil palm fruit setting on both peat and mineral soils continues to be reported, decades after the introduction of Elaeidobius kamerunicus. The population density of E. kamerunicus depends on the presence of anthesising male inflorescence. It was also previously suggested that the spikelet position on anthesising inflorescence can influence the weevil population. Therefore, this study aimed to analyse E. kamerunicus population density in relation to spikelet position across mineral and peat soil areas during the anthesising period of the male inflorescence. Sampling was conducted from July 2022 to June 2023. During the male inflorescence anthesis, weevils found on the spikelets were sampled and recorded. Sampling occurred daily from the 1st to the 5th day of anthesis. Simultaneously, additional data, including spikelet length, temperature, relative humidity, and rainfall, were also collected. Results revealed a significant difference in weevil population per spikelet based on spikelet position: on the 1st day of anthesis in mineral soil and on the 3rd day of anthesis in peat soil. The bottom spikelets consistently exhibited the highest weevil congregation, differ significantly from the population found on the top spikelets. Spikelet length also varied significantly with soil type and spikelet position. Mineral soil recorded the longest spikelets, significantly longer than those in peat soil. Conversely, the top spikelets were the shortest, significantly different from the middle and bottom spikelets. Correlation analysis between abiotic factors (relative humidity and temperature) and spikelet length against weevil population density per spikelet showed significant, albeit varied, correlations with the weevil population. These variations were observed across different anthesis days, spikelet positions, and soil types. This study highlights the influence of spikelet position on weevil population density per spikelet, providing valuable insights applicable to future weevil population censuses.

Text 126342.pdf - Published Version Download (579kB) Official URL or Download Paper: https://ejournal.ukm.my/serangga/article/view/9859...

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