Settling Success of Ceroplastes grandis (Hemiptera: Coccidae) Crawlers on Duranta erecta var. lemon (Verbenaceae)

Abstract

Ceroplastes grandis Hempel (Hemiptera: Coccidae) is a polyphagous wax scale insect. Females form unsightly clusters in heavy infestations, especially on ornamental plants and urban trees (Granara de Willink & Claps 2003). Excessive removal of plant sap causes wilting of plants. Research on C. grandis has focused on taxonomy (Granara de Willink 1999, Peronti et al. 2008, Rosa et al. 2016), and some aspects of biology, damage and management (Vaccaro & Mousqués 1996, Granara de Willink & Claps 2003, Rosa et al. 2016, Correa Franco 2018). Duranta erecta var. lemon L. (Verbenaceae) is a shrub native from southern United States to Argentina (Sanders 1984), and widely used as an ornamental plant in parks and gardens (Parodi & Dimitri 2004). Decuyper et al. (2020) reported the detection of C. grandis on D. erecta plants in Argentina, and the reduction in the plants’ ornamental value. Since insecticide application is most effective against the crawlers and second instars, which are not protected by wax cover (Smith et al. 1971, Camacho et al. 2017), knowledge of the settling behavior of crawlers on this shrub is important to developing effective management practices that reduce C. grandis populations and damage. The aim of this study was to determine how successfullyC. grandis crawlers could settle onD. erecta var. lemon plants. The settling behavior of this wax scale onD. erecta has not been addressed. First-instar C. grandis were collected from a highly infested D. erecta plant in a private garden in Paraná, Entre Ríos, Argentina (31°46′01.6′′S, 60°31′10.7′′W). Before collection, we confirmed that C. grandis was the only scale species presented on the source plant by identifying adult females based on the description of Vaccaro & Mousqués (1996). The insects were placed on moist filter papers in Petri dishes and transported to the laboratory. They were then exposed to 12°C in