Host effects on the cold hardiness strategies of Epiphyas postvittana

Commonly known as the Light Brown Apple Moth (LBAM), Epiphyas postvittana (Walker) is a recent invasive insect pest to California.  LBAM larvae have been documented to feed on more than 200 species of plants, many of which are important to agriculture and forestry.  As with many invasive, exotic species, predicting the potential for future geographic spread of LBAM is of high concern for managers.  Two factors that can greatly affect geographic distributions are host plant availability and temperature, particularly cold temperature. An insect’s cold hardiness can be influenced by the type of host it consumes.  For insects, such as LBAM, that feed on a wide variety of plants, understanding the effects of host plant on cold hardiness can aide in more accurate risk assessments of the likelihood of expansion and survival in the United States.  Here, we compare the effects of four documented host plants on LBAM development and cold hardiness. We reared late instar larvae on different hosts, and then assessed them for survival following supercooling.  Survivors were measured for subsequent developmental times, pupal weight, and adult sex ratio. We show that host plant affects LBAM cold hardiness, and discuss the implications of these data for enhancing future models of geographic spread.