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COSEWIC Assessment and Status Report on the Aweme Borer in Canada

Biology

Essentially nothing is known about the biology of the Aweme Borer, and the following information refers to the genus Papaipema in general.


Life Cycle and Reproduction

Adult Aweme Borers are nocturnal and have been collected at lights at night (M. Nielsen, personal communication 2004; D. Schweitzer, personal communication November 2004). The life cycle is undoubtedly like that of all Lepidoptera, consisting of complete metamorphosis, with egg, larva, pupa, and adult stages.

The life cycle takes one full year to complete. Female Papaipema drop eggs loosely in the vicinity of the host plant in the fall and then die. The eggs overwinter and hatch the following spring. Larvae locate and bore into the host plant, where they complete their growth within the roots or stems, usually within a two-month period. Once mature, they pupate either inside or outside the host plant, depending on species or even individuals (Forbes, 1954; Bird, 1934). They remain in the pupal stage for about a month. Adults live for about two weeks, and females appear to be relatively inactive (Bird, 1934).

Collection records for adult Papaipema aweme are from 7-26 August (Table 1), somewhat early for Papaipema species (Schweitzer 1999). Papaipema moths are active late in the night (actually early morning) hours (Schweitzer 1999).

All Papaipema species are endophagous plant borers. They utilize an unusually wide range of plant species as hosts, spread across some 22–25 plant families ranging from ferns to trees to asters and lilies. However, most individual Papaipema species are restricted to only one or a few closely related species or genera of plants (Goldstein 1999, Forbes 1954; Rockburne and Lafontaine 1976). Suggested possible hosts of the Aweme Borer include relatively large native species such as Blazing-star (Liatris sp.) or an endemic thistle (Circium sp.) (J. Troubridge, pers. comm., 2004). The difficulty of identifying the host plant is illustrated by the fact that Dr. Eric Quinter, a borer specialist who has been studying this genus for some time, was unable to identify the host plant of a new species of Papaipema recently discovered on Sable Island, despite spending two weeks on the island searching for it among the very limited plant community present there (J.D. Lafontaine, pers. comm., July 2005).

Adult Papaipema have functional mouthparts and will come to sugar baits (G. Anweiler, personal observation; M. Nielsen, personal communication, November 2004), and likely obtain nectar from one or more species of native plants.


Predation

Major natural enemies of Papaipema include mammals such as rodents and skunks (Hessel 1954, Decker 1930, Schweitzer 1999), woodpeckers (Decker 1930), as well as numerous parasitoids and predatory insects. Larvae of Papaipema may be heavily parasitized by both Hymenoptera and Diptera (Fletcher and Gibson 1907; Bird 1934). A tachinid fly, Masicera senilis Will., and a braconid wasp, Apanteles papaipemae Muesebeck, are probably the most important parasitoids of Papaipema larvae (Decker 1930). Small mammals in some cases can completely eradicate small populations of Papaipema (Hessel 1954).


Physiology

There are no species-specific data.


Dispersal/Migration

Members of the genus Papaipema are not known to migrate, and are usually collected in close proximity to the host plants. Dispersal between isolated food patches separated by up to several kilometres does occur (Schweitzer 1999).


Interspecific Interactions

There are no data. The Aweme Borer is undoubtedly dependent on one or more unknown species of larval host plant.


Adaptability

Most Papaipema species are restricted to, and dependent upon, one or a few related host plants. Papaipema species have demonstrated the ability to reoccupy patches of host plant following fire, so long as there are populations in unburned refugia in the vicinity (Schweitzer 1999).