Evaluation of New Systemic Insecticides for Elm Insect Pest Control

Abstract

Use of systemic insecticides that can be injected either into the root system or trunk of woody plants provides several potential advantages, notably in control of drift during application. Recently, new classes of insecticides with systemic activity have been developed, which may supplant the organophosphate and carbamate systemic insecticides that have previously been available. To evaluate their potential to control insects affecting shade trees, studies were conducted using imidacloprid and abamectin on elm. Soil injections of imidacloprid appeared particularly effective, controlling all three of the target pest species in this study (elm leaf beetle, European elm scale, elm leaf aphid). Both imidacloprid and abamectin also were effective against at least some elm insects when injected into trunks. Persistence of irnidacloprid was unusually long, providing second season control of all elm insect pests, although root uptake following soil injections was slow.

Effects of Dinotefuran and Imidacloprid on Target and Non-target Arthropods on American Elm

“…Imidacloprid and dinotefuran significantly reduced the abundance of European elm scale on elm. This finding is completely consistent with previous accounts of neonicotinoids providing excellent control of E. spuria on elm (Sclar and Cranshaw 1996;Szczepaniec et al 2011). Both insecticides also decreased numbers of the gall-forming aphid (C. ulmicola), illustrating that dinotefuran and imidacloprid are appropriate control measures in management of this pest on elms.…”

“…These nitroguanidine compounds affect a broad spectrum of insects by disrupting their acetylcholine nerve cell receptors (Mullins 1993). Of several neonicotinoid compounds introduced into the arboricultural marketplace, imidacloprid was the first to be widely used owing to its efficacy against several key insect pests of trees and shrubs including aphids (Sclar and Cranshaw 1996;Layton and Ma 2009), lace bugs (Gill et al 1999;Szczepaniec and Raupp 2007), scales (Sclar and Cranshaw 1996;Frank 2012), psyllids (Young 2002), adelgids (Stewart and Horner 1994;Doccola et al 2003;Webb et al 2003;Cowles et al 2006), palm bugs (Ali et al 2010), leaf beetles (Sclar and Cranshaw 1996;Lawson and Dahlsten 2003), flatheaded borers (Herms 2003;Rebek et al 2008;Smitley et al 2010), roundheaded borers (Wang et al 2005), leaf-feeding scarabs (Frank et al 2007), and leafminers (d 'Eustachio and Raupp 2001;Gill et al 2002). Not only did imidacloprid prove lethal to these pests, but it also reduced damage to red maple (Acer rubrum) caused by leafhoppers (Empoasca fabae) and flatheaded appletree borers (Chrysobothris femorata) (Oliver et al 2009;Oliver et al 2010).…”

“…First, researchers sought to determine if applications of dinotefuran resulted in elevated densities of spider mites and rust mites (Diptilomiopidae) on American elms. Second, having observed reductions in populations of sucking insects, such as European elm scale (E. spuria), following applications of imidacloprid to American elms (Sclar and Cranshaw 1996;Szczepaniec et al 2011), the effects of dinotefuran and imidacloprid on the abundance of two sucking insects, European elm scale and elm cockscomb gall aphid (Colopha ulmicola), were examined. Trees received approximately 5 cm of shredded hardwood mulch after planting and supplemental irrigation on a weekly basis in the summer and autumn of 2005 on weeks with no rainfall.…”

Managing Calico Scale (Hemiptera: Coccidae) Infestations on Landscape Trees

“…Within-tree control also was inconsistent; crawler mortality often ranged from 0% to 100% on leaves from different branches or canopy zones (Hubbard 2004). Trunk-or soil-injected imidacloprid often provides good control of aphids (Sclar and Cranshaw 1996) adelgids (Steward and Horner 1994), psyllids (Young 2002), lace bugs (Gill et al 1999), certain scales (Sclar and Cranshaw 1996), and other tree pests. In our trials, however, imidacloprid failed to control any life stage of calico scale regardless of whether applied by trunk injection in spring or summer or by soil injection in autumn, winter, or spring.…”

Life history traits ofCoccophagus gossypariae(Hymenoptera: Aphelinidae), a parasitoid of invasiveEriococcus spurius(Hemiptera: Eriococcidae) in field studies

“…The systemic insecticide imidacloprid (C 9 H 10 ClN 5 O 2 ) was used to reduce E. spurius populations in Calgary between 2005 and 2014. Imidaclorpid has also been used to control E. spurius on urban American elms elsewhere (Sclar and Cranshaw 1996;Karimzadeh and Iranipour 2017). Due to its nontarget effects on natural enemies in other systems (Rogers and Potter 2003) and increasing public scrutiny of neonicotinoid use, some municipalities are searching for other tools to control E. spurius on urban American elms.…”