Biology of Microlarinus lypriformis (Col.: Curculionidae) on Puncturevine in Southern California

Abstract

The biology of Microlarinus lypriformis (Wollaston) on puncturevine, Tribulus terrestris L., was studied in the laboratory and insectary at 27±2°C and in the field in southern California. Eggs were laid singly in small pits chewed mainly in the undersides of the central, older parts of these spreading, resupinate weeds, i.e., root crowns and stem bases. The eggs hatched in 2-3 days. The young larvae tunneled directly into the pith, where they initially confined their feeding. As the larvae matured, they also fed on the vascular tissues and inner cortex. Larvae tunneled 1-12 cm during their development, which lasted 27-28 days in the insectary. Pupation occurred in open tunnels or in cells enlarged from smaller diam tunnels. The pupal stadium lasted 4-5 days. The adults emerged from circular holes chewed mainly in the upper surfaces of stems, branches, and crowns. Adults fed on the margins of leaflets, the undersides of stems and branches, and other plant parts. Oviposition began 2-6 days after pupal ecdysis. The ovipositional periods of 27 females averaged 106±8 days, during which time 246±22 eggs were laid. Their average longevity was 123 (max.: 475) days.