ABSTRACT 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 1994–2014 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 (0–8 years after planting), adult palm trees (9–19 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.

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.

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.

Considerando o período de competição de plantas daninhas e a incidência da lagarta-do-cartucho na cultura do milho, há necessidade de aplicação, em curto intervalo de tempo, de herbicidas e de inseticidas, principalmente o nicosulfuron e o chlorpyrifos. O objetivo deste estudo foi avaliar o efeito da aplicação sequencial do nicosulfuron e do chlorpyrifos sobre a emergência de plântulas do banco de sementes, a taxa de desprendimento de CO2 (respiração basal) e o C da biomassa microbiana (CBM) do solo. Foi realizada aplicação sequencial, em solo, do nicosulfuron (doses de 0 a 64 g ha-1) associado ou não ao chlorpyrifos (0 e 240 g ha-1). Aos 20, 40 e 60 dias após a aplicação (DAA) dos produtos, todas as plântulas emergidas do banco de sementes foram identificadas em nível de espécie, sendo estimadas a frequência, densidade e abundância, além do índice de valor de importância (IVI). Aos 60 DAA, determinou-se também a taxa de desprendimento de CO2, o CBM e o quociente metabólico (qCO2), por meio da relação entre o CO2 acumulado e o CBM total do solo. A aplicação alterou severamente a massa de plântulas secas e o número de espécies nas doses superiores a 20 g ha-1 do nicosulfuron. Na presença do herbicida, as espécies com maior IVI foram Boehavia diffusa e Commelina benghalensis. Quanto aos bioindicadores do solo, foi observado decréscimo na taxa da respiração basal do solo com o aumento da dose aplicada do nicosulfuron associado ao chlorpyrifos, sem efeito na ausência do inseticida. Houve decréscimo linear no CBM em todos os casos, independentemente da aplicação do chlorpyrifos; entretanto, observou-se uma taxa de decréscimo 4,5 vezes maior para o solo que recebeu esse inseticida em conjunto com o nicosulfuron. A avaliação do qCO2 confirmou o efeito negativo da aplicação do inseticida e do herbicida. Conclui-se que a aplicação de chlorpyrifos + nicosulfuron promove impacto negativo sobre o banco de sementes e sobre a atividade microbiana do solo.

In the period of competition of weeds and the incidence of fall armyworm in the corn crop there is a need for herbicide and insecticide such as nicosulfuron and chlorpyrifos application within short time intervals. The aim of this study was to evaluate the effect of sequential applications of nicosulfuron and chlorpyrifos on the emergence of seedlings of the seed bank in the soil, the basal CO2 emission rate, and the microbial biomass carbon (MBC) of soil. Sequential applications of nicosulfuron (doses from 0 to 64 g ha-1) with or without chlorpyrifos (0 and 240 g ha-1) were performed. At 20, 40 and 60 days after application (DAA) of the products, the species of all seedlings that emerged from the seed bank were identified, and the frequency, density and abundance estimated, as well as the importance value IV. Sixty DAA the CO2 emission rate and CBM were were also determined, and based on the relationship between the accumulated CO2 and total soil MBC the metabolic coefficient (qCO2) was estimated. The application of nicosulfuron rates of over 20 g ha-1 severely affected the seedling dry weight and number of species. In the presence of the herbicide, the species with highest IV were Boehavia diffusa and Commelina bengalensis. There was a decrease in the basal soil respiration rate with increasing nicosulfuron doses, in the presence as well as in the absence of the insecticide chlorpyrifos. There was a linear decrease in MBC in all cases regardless of the chlorpyrifos application, although the reduction was 4.5 times greater in soil that received the combined application of the insecticide and nicosulfuron. The qCO2 confirmed the negative effect of the application of insecticide and herbicide. It was concluded that the application of chlorpyrifos + nicosulfuron causes a negative impact on the seeds in the soil and the soil microbial activity.