BIOLOGICAL CONTROL-WEEDS Introduction, Establishment, and Potential Geographic Range of Carmenta sp. nr ithacae (Lepidoptera: Sesiidae), a Biological Control Agent for Parthenium hysterophorus (Asteraceae) in Australia

Parthenium (Parthenium hysterophorus L.), a major weed causing economic, environmental, and human and animal health problems in Australia and several countries in Asia, Africa, and the PaciÞc, has been a target for biological control in Australia since the mid-1970s. Nine species of insects and two rust fungi have been introduced as biological control agents into Australia. These include Carmenta sp. nr ithacae, a root feeding agent fromMexico. The larvae ofC. sp. nr ithacae bore through the stem-base into the root where they feed on the cortical tissue of the taproot. During 1998Ð2002, 2,816 larval-infested plants and 387 adults were released at 31 sites across Queensland, Australia. Evidence of Þeld establishment was Þrst observed in two of the release sites in central Queensland in 2004. Annual surveys at these sites and nonrelease sites during 2006Ð2011 showedwide variations in the incidence and abundance ofC. sp. nr ithacaebetween years and sites. Surveys at three of the nine release sites in northern Queensland and 16 of the 22 release sites in central Queensland conÞrmed the Þeld establishment of C. sp. nr ithacae in four release sites and four nonrelease sites, all in central Queensland. No Þeld establishment was evident in the inland region or in northern Queensland. ACLIMEXmodel based on the native range distribution ofC. sp. nr ithacae predicts that areas east of the dividing range along the coast are more suitable for Þeld establishment than inland areas. Future efforts to redistribute this agent should be restricted to areas identiÞed as climatically favorable by the CLIMEX model.