A low cost and labor-efficient method for rearing an invasive beetle, Carpophilus truncatus (Coleoptera: Nitidulidae)

The carpophilus beetle, Carpophilus truncatus Murray, 1864 (Coleoptera: Nitidulidae) is an invasive pest recently detected in California's tree nut crop orchards. Here we report a simple, labor-saving, and cost-effective rearing system for C. truncatus utilizing banana and industrial sand components. Banana slices served as both a larval and adult diet source as well as a moisture source to facilitate pupation within the underlying sand. The combination of banana and sand within a single container successfully supported the development of all C. truncatus life stages over multiple generations. The average developmental times recorded in rearing units placed under environmental conditions of 26°C, 60% relative humidity, and 16:8 h (light:dark) photoperiod were: egg to wandering stage larva, 7.54 days; wandering stage to adult, 11.08 days; and adult longevity, 94.33 days. These banana-sand rearing units facilitated the easy collection of all C. truncatus developmental stages, except for eggs. To address this challenge, standalone oviposition chambers utilizing a lima bean-based agar diet were evaluated. These chambers effectively enabled the collection as well as tracking of eggs for different research purposes. The average developmental time recorded for eggs, from initial oviposition to neonate hatching, was 3.20 days. These rearing as well as egg collection approaches provide cost-effective tool to investigate biology, life-history traits and ecology, as well as evaluate approaches to control this invasive pest.