Mediterranean
Puncturevine (Tribulus terrestris)
Eggs are dark yellow and cylindrical. Larvae are C-shaped with white to yellow-brown bodies and dark brown head capsules. Pupae are creamy white and up to 4 mm long. Adults are a mottled brown and covered with erect grayish hairs that make them appear shaggy. Adults are typically 4–5 mm long and have short, broad snouts.
Adults emerge in spring and feed on the bottom of puncturevine stems throughout the growing season, leaving round scars. Females chew pits in young fruits and lay eggs before sealing the pit with a dark cement. Hatching larvae feed on seeds and fruit tissue, developing through four instars. They pupate within their feeding cell inside attacked fruits. New adults typically emerge within five days. The period from egg to adult frequently takes 25–30 days. In warm climates, up to four generations may be produced throughout a growing season, but fewer generations are produced at colder location. Adults overwinter in soil litter.
Both M. lareynii and M. lypriformis attack caltrop (Kallstroemia) species native to the southwestern USA. Adults have also been found on numerous exotic species (some of economic importance), though impact to those species is typically negligible. These weevils should not be released at any sites where native caltrop species occur.
Adult feeding is usually insignificant and doesn’t harm the plant. Larval feeding destroys seeds and may induce seed abortion, though the damaging spines of fruits still develop. This weevil does not reduce problems caused by the spininess of fruits produced during the current or past growing seasons; however, it may help decrease the number of seeds produced within the fruits. Over time and under ideal conditions, this may have an impact on puncturevine populations.
Andreas, J.E., K. Bowers, and J. Milan. 2024. Puncturevine Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2024-9-PUNCTUREVINE-A. https://bugwoodcloud.org/resource/files/29216.pdf