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The Impact of CO2 on the Emergence of an Oil Palm Weevil

Paper Reviewed
Amanina, N.S., Hasnudin, M.Y., Haniff, M.H., Roslan, M.N., A'Fifah, A.R. and Ramle, M. 2016. Effects of high carbon dioxide level on the emergence of oil palm pollinating weevil, Elaeidobius kamerunicus. Journal of Oil Palm Research 28: 172-176.

Writing as background for their study, Amanina et al. (2016) note that "the direct physiological effects of enriched CO2 atmospheres for plant species are becoming increasingly well documented," citing the meta-analysis of Curtis and Wang (1998). However, they also write that some of these effects could alter the quality and quantity of food available for insect herbivores. Thus, they set out to examine this possibility for oil palm (Elaeis guineensis) and its main insect pollinator, the oil palm weevil (Elaeidobius kamerunicus).

Worldwide, palm oil production presently amounts to over 50 million metric tons annually. The lion's share of its use is in the commercial food industry, where it has become an increasingly sought-after commodity due to its high level of antioxidants and relatively inexpensive price. It is an important agricultural product that will likely increase in prominence in the future.

Historically, oil palm pollination was done manually; but it was a very labor-intensive and expensive process. Commercial plantations therefore sought a natural pollination alternative to human labor and found a substitute in the oil palm weevil. Surprisingly, Amanina et al. report that pollination by this insect herbivore "increases fruit set and subsequently improves the oil palm yield (Ponnamma, 1999; Caudwell, 2001)." Thus, the six researchers from the Malaysian Palm Oil Board set out to investigate the impact of elevated CO2 on oil palm weevil performance.

To accomplish their objective, the authors bred weevils on oil palm spikelets maintained under ambient (400 ppm) and twice-ambient (800 ppm) CO2 levels in controlled-environment chambers for a period of ten days after incubation, which period allowed the weevils to pass through the egg, neonate, larva, nymph and adult stages, after which the weevils were euthanized and examined for differences that developed among the different CO2 treatments.

The results indicated, in the words of the authors, that "the emergence of oil palm pollinating weevil, E. kamerunicus, was not affected when incubated in 800 ppm of CO2." Statistically, there was no difference in the weevil counts of the two CO2 treatments. And because it had no effect on weevil emergence, there is no reason to presently suspect that rising atmospheric CO2 concentrations will have any negative impact on future oil palm production.

Caudwell, R.W. 2001. Insect pollination of oil palm -- time to evaluate the long-term viability and sustainability of Elaeidobius kamerunicus? Planter 77: 181-190.

Curtis, P.S. and Wang, X. 1998. A meta-analysis of elevated CO2 effects on woody plant mass, form and physiology. Oecologia 113: 299-313.

Ponnamma, K.N. 1999. Diurnal variation in the population of Elaeidobius kamerunicus on the anthesizing male inflorescence of oil palm. Planter 75: 405-410.

Posted 31 October 2016