Oil palm age and genotype interfere with defoliator lepidopteran infestation

The state of Pará has oil palm plantings of different ages and distinct genotypes. The understanding of which factors influence the occurrence and abundance of defoliating caterpillars in palm groves is paramount for control strategies based on integrated pest management (IPM). This study quantified the effect of oil palm age independently, and that of oil palm age and genotype, on the occurrence and abundance of defoliating caterpillars. Data were collected from 1994­2014 and consisted of counting the average number of caterpillars/leaf/parcel. For Opsiphanes invirae and Talima sp., leaf 17 was sampled; for Acharia spp., Euclea sp., Euprosterna elaeasa, Natada sp., and Automeris liberia, leaf 25 was sampled. For Oiketicus kirbyi, Antaeotricha sp., and Brassolis sophorae no specific leaf was considered. Palm trees were classified into three groups: young palm trees (0­8 years after planting), adult palm trees (9­19 years after planting), and old palm trees (over 20 years after planting). Talima sp. showed the highest population peak followed by O. invirae, Acharia spp., Elaeis elaeasa and Euclea sp. This study concludes that genotype has an impact on the infestation by defoliating caterpillars. Also, oil palms at reproductive age are more prone to higher infestation levels than young trees. While population levels of defoliating caterpillars are low in general, outbreaks are frequent. Importantly, intraspecific genotypes are more vulnerable than interspecific genotypes to infestations by defoliating caterpillars. This study contributes to the bioecological knowledge on defoliating caterpillars on oil palm and therefore provides important information to strengthen integrated pest management practices.

Validation of the sampling methodology for Opsiphanes invirae caterpillars on oil palm plantations in the Brazilian Amazon / Validação da metodologia de amostragem para lagartas de Opsiphanes invirae em plantios de palma de óleo na Amazônia brasileira

ABSTRACT: This study validated the use of leaf 17 on the sampling of Opsiphanes invirae Hübner (Lepidoptera: Nymphalidae) through the quantification of caterpillar abundance on the different spirals leaves, in comparison to leaf 17, and, on the apical, intermediate and basal leaf regions. This study was performed in the state of Pará, between March-2014 and March-2015. Results confirmed that leaf 17 is the most adequate method for monitoring this defoliator pest.

RESUMO: Esta pesquisa validou a utilização da folha 17, nas amostragens de Opsiphanes invirae Hübner )Lepidoptera: Nymphalidae), através da quantificação da abundância de lagartas nas diferentes folhas que compõem os espirais em comparação com a folha 17, e, em diferentes regiões da folha (apical, intermediária e basal). O estudo foi realizado no Pará entre março de 2014 e março de 2015. Os resultados confirmam que a folha 17 é a mais adequada para ser utilizada no monitoramento desse desfolhador.