Evolution of cannibalism in the Colorado potato beetle, Leptinotarsa decemlineata, in response to a host-plant shift?

The Colorado potato beetle, Leptinotarsa decemlineata, is a pest on domestic potato, Solanum rostratum, in the United States, Canada, and Europe.  However, this beetle is actually native to Mexico, where it feeds on buffaloburr, S. rostratum, rather than potato.  Due to the patchy distribution and smaller size of buffaloburr compared to potato, competition in CPB is predicted to be higher in its native range.  Neonates can reduce competition by cannibalizing eggs within their clutch.  Therefore, cannibalism rates are also expected to be higher in the native range.  Preliminary field work identified two distinct populations in Mexico with clutches significantly different in size from each other and from a population on Long Island, NY.  Cannibalism rates in these populations were also significantly different, with the Mexican population with the largest clutches also displaying the highest rates of cannibalism.  The results of follow-up work will also be discussed.