Comparative morphology of the larvae of the palm weevils Dynamis borassi (Fabricius) and Rhynchophorus palmarum (Linnaeus) (Curculionidae: Dryophthorinae): Two major pests of peach palms in the Neotropics

Abstract

The morphology of the larvae of Dynamis borassi (Fabricius) and Rhynchophorus palmarum (Linnaeus) was compared, described and illustrated. A complete definition of subtribe Rhynchophorina at the larval stage was elaborated, based on mature and submature larvae, and characters of the first instar larvae are provided for the first time. Diagnostic characters to distinguish the larvae of D. borassi and R. palmarum are mainly from the epipharynx and maxillae, but the abdominal terminal plate also provides differential features that can aid in the identification. The characterization of both species at the larval stage is expected to be useful in the implementation of new control strategies in palm plantations in South America. For practical reasons, a comparative table is appended in Spanish to serve as a quick diagnostic guide for species identification.

Perspectives for Synergic Blends of Attractive Sources in South American Palm Weevil Mass Trapping: Waiting for the Red Palm Weevil Brazil Invasion

“…The Rhynchophorus genus includes oligophagous insect pests, which reproduce on a diverse variety of palm species (Arecales: Arecaceae) [ 15 ] with a complete metamorphosis, including the egg, larva, pupa, and adult stages [ 21 ]. In adulthood, males release the aggregation pheromone to attract males and females to a new food source when they reach a suitable host plant [ 22 , 23 , 24 , 25 ].…”

Dynamis borassi (Coleoptera: Curculionidae), a New Potential Pest to the Palms (Arecaceae): An Early Warning for the Palm Producers

“…This confirms the idea that the latter species is opportunistic, as observed previously by Alpizar et al (2002), and likely uses the damage caused by D. borassi as its entry point. It is likely that the joint attack of these 2 weevil species causes extensive structural damage until the crown of the palm finally drops (Pardo-Lorcano et al 2016;Vásquez-Ordóñez et al 2020). Early symptoms are negligible and quite difficult to detect.…”

“…Although both weevils are sympatric and have been around for yr, the known host range for R. palmarum is wider significantly than that for D. borassi (EPPO 2005;Bautista-Giraldo et al 2020;Vásquez-Ordóñez et al 2020). This makes the latter more vulnerable to changes in the environment, especially deforestation or selective harvesting of its host palms, and may have triggered a change in its host selection and acceptance behavior.…”

“…The pupae were kept in 1.5 L multi plastic storage boxes (Home Collection, Cali, Colombia) until adults emerged, which were then stored in 96% ethanol. Both the adults collected from the stems and larvae collected in inflorescences were identified to species level following the keys of Wattanapongsiri (1966), Chamorro (2019), and direct examination of specimens as documented in Vásquez-Ordóñez et al (2020).…”

“…The latter initially was attributed to R. palmarum, and a general pest alert was published by the Colombian phytosanitary authority (ICA 2015). However, Pardo-Locarno et al (2016) and later Vásquez-Ordóñez et al (2020) associated the problem with the Neotropical palm weevil, D. borassi. Both weevil species share similar morphological characteristics that make diagnosis difficult, particularly in the larval stage, where the damage occurs (Vásquez-Ordóñez et al 2020).…”