Life cycle and larval growth of Dynamis borassi (Coleoptera: Dryophthoridae), an emerging pest to the peach palm

Abstract

Dynamis borassi Fabricius (Coleoptera: Dryophthoridae) is widely distributed in South America and is an economic pest in commercially important palms (Arecaceae). In Colombia, peach palm production is of socio-economic importance in the Pacific region but has decreased dramatically due to a weevil complex that attacks the top of the palm. Dynamis borassi is the principal cause of this damage. Despite its importance, the biology of this species is unknown. A rigorous study of life cycle duration, as well as each stage of development, is key to future ecological and behavioural studies and essential in the design of comprehensive pest management plans. We report details of the life history of this pest in a laboratory colony. Life cycle and the larval growth were studied under controlled laboratory conditions (27 ± 1 °C and 75 ± 5% RH) using two artificial diets: Diet 1 without peach palm inflorescences and Diet 2 with 100 g of inflorescences. The egg stage lasted 3.5 ± 0.1 days, the larval stage 165.5 ± 4.7 days for Diet 1 and 153.8 ± 3.9 days for Diet 2, and the pupal stage 37 ± 1.7 days for Diet 1 and 39.7 ± 1.2 days for Diet 2. Twelve instars were observed. The instar when pupation took place varied from instar VII to XII. The weight gain curve had four growth phases with both diets. Each diet produced a different life cycle duration and growth rate. No significant differences were found in the life cycle between the diets.