Biological Control ofFenusa pusilla(Hymenoptera: Tenthredinidae) in the Northeastern United States: A Thirty-Four Year Perspective on Efficacy

Abstract

Parasitoid releases against the birch leafminer Fenusa pusilla (Lepeletier) (Hymenoptera: Tenthredinidae) in eastern North America began in 1974, with releases in eastern Canada, followed by others in the Middle Atlantic States and New England. Of 4 parasitoids released, only 1, the ichneumonid Lathrolestes nigricollis (Thompson), established and spread widely. Studies of its preliminary impacts were made in several locations in the 1980s and 1990s, but full impact of the parasitoid on host density was not yet achieved in that period.Here we report results of surveys in 7 states (MA, CT, RI, NY, PA, NJ, DE) in 2007 documenting the current birch leaf miner levels (as % of leaves mined in spring) and parasitism. Survey results show that the pest has declined dramatically to barely detectable levels in 5 states (MA, CT, RI, NY, PA) but that in southern NJ, the pest remains abundant (ca 50% leaves mined) despite significant parasitism levels. Survey results, in context with previous evaluations made when populations were still declining, show that the project has been completely successful in much of the northeastern USA, but that there is a southern limit to efficacy in mid-New Jersey. Possible reasons for lack of control in this area, in contrast to high levels of control elsewhere, are discussed.

Effect of Tenthredinid Leaf Miner Invasions on Growth of Alaska White Birch in Anchorage, Alaska, USA, and the Interaction with Biological Control of Amber-Marked Birch Leaf Miner

“…The current lack of parasitoids associated with H. nemoratus in southeastern Alaska and the leaf miner's high density could potentially be corrected by introducing the species' more important parasitoids from its native range. Success in such an effort is likely, given that 2 other invasive tenthredinid sawflies that mine birch leaves (F. pumila and P. thomsoni) have been controlled through similar classical biological control introductions (F. pumila [Van Driesche et al 1997;Casagrande et al 2009] and P. thomsoni [Soper 2012;Soper et al 2015;Soper & Van Driesche 2019;Andersen et al 2021]), and earlier efforts in the eastern US for control of H. nemoratus (Dowden 1941) provide valuable suggestions for parasitoid species likely to be useful.…”

“…In Alaska, 3 of these 5 species are present: Heterarthrus nemoratus (Fallén), Fenusa pumila Leach, and Profenusa thomsoni (Konow), while 2 others, Fenusella nana (Klug), and Scolioneura vicina Konow (all Hymenoptera: Tenthredinidae), have not yet been recorded there. In eastern North America, biological control programs have been carried out to control F. pumila (Van Driesche et al 1997;Casagrande et al 2009) and H. nemoratus (Dowden 1941), and in western North America for control of P. thomsoni (Soper 2012;Soper et al 2015;Soper & Van Driesche 2019;Andersen et al 2021).…”

Invasive leafminers on woody plants: a global review of pathways, impact, and management

“…Therefore, biological control programmes were implemented from 1970s to the 2000s in USA and Canada. Four parasitoids from Europe were introduced to North America, and two specific larval parasitoids, the ichneumonids Lathrolestes nigricollis and Grypocentrus albipes, became established (Langor et al 2000, Casagrande et al 2009. These introductions, in particular those of L. nigricollis, resulted in a strong decrease in damage levels throughout the introduction range, except in southern New England where outbreaks still occur for unclear reasons (Casagrande et al 2009).…”

Review of North European species of the genus Lathrolestes (Hymenoptera, Ichneumonidae) with description of one new species from Öland (Sweden)

“…This species was brought from Europe (Friend 1933) and became an important pest (Fuester et al 1984). Lathrolestes nigricollis has been successfully used against this species of sawfly (Raske & Jones, 1975, Guevremont & Quednau, 1977, van Driesche et al, 1997, Langor et al, 2000, Casagrande et al, 2009. An attempt was made to use the same species of Lathrolestes against another invasive birch pest, Profenusa thomsoni (Langor et al, 2000).…”