Canadian Forest Service Publications

Notes on the life-history of the balsam shootboring sawfly in the Maritimes region. 2014. Carleton, R.D.; Johns, R.C.; Morrison, A.; Morin, B. Journal of the Acadian Entomological Association 10: 23-29.

Year: 2014

Issued by: Atlantic Forestry Centre

Catalog ID: 35736

Language: English

Availability: PDF (download)

Mark record


Balsam shootboring sawfly (BSS), Pleroneura brunneicornis Rowher (Hymenoptera: Xyelidae), is a poorly understood insect pest of balsam fir (Abies balsamea [L.] Mill. (Pinaceae)) in northeastern North America. Recent increases in BSS populations have raised concerns among commercial Christmas tree growers, prompting research on its emergence phenology, larval development, and parasitism. Ground emergence traps in New Brunswick (NB) and Nova Scotia (NS) indicated adults emerged from the soil immediately after snow had melted from beneath balsam fir tree crowns in mid to late April. Adults were collected from emergence traps for 2 weeks and remained active in or on trees until the end of May. Both mating and oviposition were observed and photographed up until the end of May in NB. Weekly shoot dissections from stands in NB indicated the presence of four larval instars. All larvae had exited shoots by the end of June, presumably to spin cocoons in the duff layer where overwintering occurs. Parasitoids caused mortality throughout the larval developmental period and appear to be a significant mortality factor for BSS, with 52% of fourth-instar larvae in NB showing signs of parasitism.

Plain Language Summary

Pest management requires understanding numerous pieces of basic information about the pest before monitoring programs, density–damage relationships, and mitigation techniques can be developed. Essential to this process is an understanding of the pest’s biology and ecology within a given set of environmental parameters. This information can then be used to create pest monitoring, density–damage relationships, mitigation techniques, and so on. Here, we provide such a framework for the balsam shoot boring sawfly, Pleroneura brunneicornis (Hymenoptera: Xyelidae), in New Brunswick and Nova Scotia, where it is a growing pest concern in young intensively managed balsam fir (Abies balsamea) stands. We report key information on emergence patterns, mating behaviors, larval growth and development patterns, as well as parasitism.