Local Agricultural Management Filters Morphological Traits of the South American Palm Weevil (Rhynchophorus palmarum L.; Coleoptera: Curculionidae) in Ornamental Palm Plantations

Abstract

Insect pests show phenotypic plasticity as a function of resource availability and limiting conditions. Although Rhynchophorus palmarum displays high variation in certain morphological traits, it is still not clear how and which of these are being filtered along agricultural management gradients in palm plantations. This study assesses the influence of biophysical structure of ornamental palm plantations and agrochemical use on morphological traits of adults in 15 permanent plots of ornamental palm plantations in Veracruz, Mexico. A total of 4972 adults were and their body length, pronotum width, rostrum length, and mesothorax depth were measured. Body length and mesothorax depth of adults of both sexes were greater in plantations with a high diversity of palm species and frequency of fertilizer use. Rostrum length of females increased as a function of palm density, and pronotum width of both sexes was positively related with the use of insecticides. Local characteristics of agricultural management of palm plantations might filter integrated, adaptative, and environment-specific phenotypes. This is the first ecological study of the south American palm weevil that provides new insights on the current intensive management of ornamental palm plantations that far from controlling, benefits current geographic expansion, demographic outbreak, and economic impact of this pest.

Taxonomy, Biology, Symbionts, Omics, and Management of Rhynchophorus Palm Weevils (Coleoptera: Curculionidae: Dryophthorinae)

“…In Egypt, total losses due to R. ferrugineus infestations of date palms from 1992 to 2019 were estimated to be US$400 million, with an estimated total annual management cost of approximately US$20 million (1). Losses incurred by ornamental palm growers in Veracruz, Mexico due to R. palmarum-RRN infestations are estimated at US$6,000 per hectare (162). Similarly, R. palmarum-RRN infestations can cost oil palm producers in Costa Rica millions of US dollars per year (159).…”

“…An alternative approach is to cut infested trunk parts into logs and treat with insecticides to kill emerging weevils or adults attracted to cut material (72). Interestingly, diversity and density of palms in ornamental nurseries and frequency of fertilizer and insecticide use affect R. palmarum phenotypes, potentially increasing pestiferousness (162).…”