Biological control of puncturevine Tribulus terrestris in California after twenty years of activity of introduced weevils

Fifteen years of field tests were conducted in California on 1,200 plots infested with the annual puncturevine (T. terrestris L.) in order to examine the effect of 2 introduced weevils, Microlarinus lareynii (Jacquelin du Val) and M. lypriformis Wollaston (Col.: Curculionidae), on puncturevine. Since 5 of the 6 series of plots marked a substantial reduction in viable seed production and puncturevine coverage, it is suggested that the 2 introduced weevils curtailed the puncturevine population's capacity to compensate in the natural situation and significantly contributed to the decline in puncturevine density.