Biology and Ecology of a Mesquite Twig Girdler, Oncideres rhodosticta,1 in West Texas2

Abstract

Oncideres rhodosticta Bates (Coleoptera: Cerambycidae) causes severe pruning of small branches of mesquite, Prosopis glandulosa Torr., in many areas of Texas. Adults emerge from galleries in girdled branches from late August through November. They feed on tender bark of mesquite around the buds, thorns, and small limbs. Eacli female girdles about one branch and deposits about 8 elliptically ovate eggs beneath the bark of the branch. Within 10–14 days, 98% of the eggs hatch and the larvae feed upon the sapwood, opening the oviposition scar to expel frass after about 3 months. Pupation occurs in late August and early September and is preceded by a prepupal stage. Each larva consumes about 1.44 cc of mesquite wood during its development. Parasites and predators kill 15–22% of the larvae while 34–55% die from undetermined causes. Larvae are attacked by parasites in the families Chalcedectidae, Pteromalidae, Eupelmidae, and Eurytomidae, as well as by predators in the family Cleridae. Twig girdler larvae may compete for space and food with other cerambycids and several species of bostrichids. About 31% of all girdled branches are broken off by wind storms and livestock before adults emerge, resulting in high mortality of the larvae from high temperatures in the branches near the soil surface.