PHYSIOLOGICAL ECOLOGY Laboratory Rearing of Agonopterix alstroemeriana, the Defoliating Poison Hemlock (Conium maculatum L.) Moth, and Effects of Piperidine Alkaloids on Preference and Performance

Conium maculatum L. (Apiaceae), or poison hemlock, is an invasive plant native to Europe that has become extensively naturalized throughout North America. This species contains piperidine alkaloids, including coniine and -coniceine, that are highly toxic to vertebrates. C. maculatumwas relatively free from herbivores in North America until the accidental introduction 30 yr ago of its monophagous European associate Agonopterix alstroemeriana (Clerck) (Lepidoptera: Oecophoridae).Atpresent,A.alstroemeriana iswidespreadacross theUnitedStates, and in someareas, suchas theNorthwest, can inßict substantial damageon its host plant, leading todesiccation anddeath. A. alstroemeriana has been used in recent years for the biological control of C. maculatum, although its use has been limited by the availability of larvae, which are Þeld-collected fromearly tomid-spring, and by the lack of available information about its life history and feeding habits. Here we describe a laboratory-rearing protocol incorporating a simulated winter to induce diapause and a semideÞned artiÞcial diet that allows the production of multiple generations per year and enabled us to determine the number and duration ofA. alstroemeriana developmental stages. The development of the artiÞcial diet also permitted studies of preference and performance ofA. alstroemeriana in relation to hostplant chemistry. Rearing A. alstroemeriana on artiÞcial diet supplemented with 1.5% DW coniine had no adverse impact on ultimate instar growth or performance. In a feeding behavior assay, the presence of coniine in the diet increasedA. alstroemeriana consumption three-fold relative to control diet. This behavioral response contrasts dramatically with that of Agonopterix clemensella, a native Apiaceae specialist thatdoesnotuseC.maculatum as ahost; of 30 larvae tested, 29 fedexclusivelyondiets lacking supplemental coniine. The rearing protocol and artiÞcial diet presented here can facilitate further studies of ecological and evolutionary responses of C. maculatum after its reassociation with a coevolved herbivore in North America.