Life history and biological control of Gluphisia septentrionis

Gluphisia septentrionis Walker (Lepidoptera: Notodontidae) has been a major pest in Pacific Northwest irrigated hybrid poplars since 2008. Several thousand acres are sprayed each year to control this pest. The lack of information about G. septentrionis limits the improvement of the current integrated pest management and makes pesticides the most common control method. In 2010, research was conducted to gain information about the life history of G. septentrionis. To fulfill the research objective, a laboratory colony was established, light trapping was conducted and field observations were recorded. The G. septentrionis life cycle takes 36 to 45 days. The larval stage is 19 to 25 days long, with the fifth instar lasting five to six days. The final instar is the most damaging, consuming 90% of a 3”x3” leaf in one day. Light trapping indicated G. septentrionis started to fly in late-May. Field observations showed this pest had two larval generations, one in June and another one in September. Naturally occurring beneficial arthropod fauna was identified attacking G. septentrionis during our field surveys. This group of biological control agents includes Trichogramma sp. (Trichogrammatidae), Eulophus orgyiae (Eulophiidae), a parasitoid fly (Tachinidae) and a stink bug (Pentatomidae). In August 2010, Trichogramma sp. parasitized approximately the 80% of G. septentrionis eggs and E. orgyiae attacked close to the 40% of G. septentrionis larvae. These high rates of parasitism prevented a second outbreak of this pest in 2010 that in previous years required a chemical application.