Fiorinia externa and Tsugaspidiotus tsugae (Homoptera: Diaspididae): Distribution, Abundance, and New Hosts of Two Destructive Scale Insects of Eastern Hemlock in Connecticut

McClure, Mark S.; Fergione, Michael B.

doi:10.1093/ee/6.6.807

Cited by 32 publications

(45 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1B, 4B). Bold lines indicate ranges reported in published literature (Butin et al 2005;McClure 1978McClure , 1980McClure 1987;McClure 1989aMcClure , 1989bMcClure and Fergione 1977;Souto et al 1996;USDA 2002 Between 1997/98 and 2005, the number of EHSoccupied hemlock stands in CT increased >350% (Fig. 2B).…”

Section: Discussionmentioning

confidence: 66%

See 1 more Smart Citation

Range expansion and population dynamics of co-occurring invasive herbivores

et al. 2007

View full text Add to dashboard Cite

Although a range of studies have suggested that competition plays a critical role in determining herbivore assemblages, there has been little work addressing the nature of interactions between competing invasive herbivores. We report the results of research on the hemlock woolly adelgid Adelges tsugae ('HWA') and elongate hemlock scale Fiorinia externa ('EHS'), invasive herbivores that both feed on eastern hemlock (Tsuga canadensis). HWA has been linked to hemlock mortality throughout the East Coast of the US; the loss of hemlock threatens to permanently alter surrounding ecosystems. We assessed the spread and impact of both species by resurveying 142 hemlock stands across a 7,500 km 2 latitudinal transect, running from coastal CT to northern MA, for HWA and EHS density as well as hemlock mortality. These stands had been previously surveyed in either 1997-1998 (CT) or 2002. While the number of HWAinfested stands has increased, per-stand HWA density has substantially decreased. In contrast, EHS distribution and density has increased dramatically since 1997-1998. Hemlock mortality was much more strongly related to HWA density than to EHS density, and many stands remain relatively healthy despite an overall increase in hemlock mortality. There was a positive correlation between HWA and EHS densities in stands with low mean HWA densities, suggesting the potential for host-plant-mediated facilitation of EHS by HWA. Our findings underline the importance of research explicitly addressing interactions between competing invasive species, and of determining the potential consequences of these interactions for the invaded ecosystem.

show abstract

Section: Discussionmentioning

confidence: 66%

“…It is found almost exclusively on eastern hemlock in the northeastern US (McClure and Fergione 1977). Although EHS is univoltine and reproduces sexually, its life cycle is otherwise very similar to that of HWA: overwintering adults lay eggs that hatch in late spring to produce 'crawlers' that can both move actively and be dispersed passively.…”

Section: Methodsmentioning

confidence: 99%

Range expansion and population dynamics of co-occurring invasive herbivores

et al. 2007

View full text Add to dashboard Cite

show abstract

“…However, over the past Ϸ10 yr, their incidence and abundance has greatly increased. Damaging populations for elongate hemlock scale have generally followed its expanding distribution on eastern hemlock, Tsuga canadensis (L.) Carriè re (McClure and Fergione 1977), whereas infestations of A. cryptomeriae have been associated with their inadvertent movement with infested nursery stock (R.S.C., personal observation). For both species, the greatest damage to Christmas tree plantations was initially close to the coast, and has since rapidly expanded inland.…”

mentioning

confidence: 99%

Optimizing a Basal Bark Spray of Dinotefuran to Manage Armored Scales (Hemiptera: Diaspididae) in Christmas Tree Plantations

Cowles¹

2010

jnl. econ. entom.

View full text Add to dashboard Cite

The armored scales Fiorinia externa Ferris and Aspidiotus cryptomeriae Kuwana (Hemiptera: Diaspididae) are increasingly damaging to Christmas tree plantings in southern New England. The systemic insecticide dinotefuran was investigated for selectively suppressing armored scale populations relative to their natural enemies in cooperating growers' fields in 2008 and 2009. Banded soil application of dinotefuran resulted in poor control. However, a dinotefuran spray applied to the basal 25 cm of trunk resulted in its absorption through the bark, translocation to the foliage, and good efficacy. The basal bark spray did not significantly impact the activity of predators Chilocorus stigma (Say) or Cybocephalus nipponicus Enrody-Younga and in 2009 showed a dosage-dependent improvement in the percentage of scales parasitized by Encarsia citrina Craw. A field dosage-response factorial experiment revealed that a 0.25% (vol:vol) addition of a surfactant with dinotefuran did not enhance insecticidal effect. Probit-transformed scale population reduction relative to the untreated check was subjected to linear regression analysis; reduction of scale populations was proportional to the log of insecticide dosage, whereas basal bark spray efficacy declined in proportion to the cube of tree height. The regression equation can be used to optimize dosage relative to tree height. Excellent efficacy resulted from basal bark spray application dates of 28 April (prebud break) to mid-June, but earlier spray timing within that treatment window had fewer crawlers discoloring new growth with their short-lived feeding. A basal bark spray of dinotefuran is well suited for integration with natural enemies to manage armored scales in Christmas tree plantations.

show abstract

“…In the mid-1970s, it began to rapidly expand its invaded range and has now been reported in .14 eastern states (Lambdin et al 2005). It is found almost exclusively on eastern hemlock in the northeastern United States (McClure and Fergione 1977). Although EHS is univoltine in the northern portion of its invaded range and reproduces sexually, its life cycle is otherwise similar to that of HWA: overwintering adults lay eggs that hatch in late spring (one to two months later than HWA) to produce crawlers that can move actively or be dispersed passively.…”

Section: Natural History Of the Systemmentioning

confidence: 99%

Exploitative Competition Between Invasive Herbivores Benefits a Native Host Plant

Preisser

Elkinton

2008

Ecology

View full text Add to dashboard Cite

Abstract. Although biological invasions are of considerable concern to ecologists, relatively little attention has been paid to the potential for and consequences of indirect interactions between invasive species. Such interactions are generally thought to enhance invasives' spread and impact (i.e., the ''invasional meltdown'' hypothesis); however, exotic species might also act indirectly to slow the spread or blunt the impact of other invasives. On the east coast of the United States, the invasive hemlock woolly adelgid (Adelges tsugae, HWA) and elongate hemlock scale (Fiorinia externa, EHS) both feed on eastern hemlock (Tsuga canadensis). Of the two insects, HWA is considered far more damaging and disproportionately responsible for hemlock mortality. We describe research assessing the interaction between HWA and EHS, and the consequences of this interaction for eastern hemlock. We conducted an experiment in which uninfested hemlock branches were experimentally infested with herbivores in a 2 3 2 factorial design (either, both, or neither herbivore species). Over the 2.5-year course of the experiment, each herbivore's density was ;30% lower in mixed-vs. single-species treatments. Intriguingly, however, interspecific competition weakened rather than enhanced plant damage: growth was lower in the HWAonly treatment than in the HWA þ EHS, EHS-only, or control treatments. Our results suggest that, for HWA-infested hemlocks, the benefit of co-occurring EHS infestations (reduced HWA density) may outweigh the cost (increased resource depletion).

show abstract

Fiorinia externa and Tsugaspidiotus tsugae (Homoptera: Diaspididae): Distribution, Abundance, and New Hosts of Two Destructive Scale Insects of Eastern Hemlock in Connecticut

Cited by 32 publications

References 0 publications

Range expansion and population dynamics of co-occurring invasive herbivores

Range expansion and population dynamics of co-occurring invasive herbivores

Optimizing a Basal Bark Spray of Dinotefuran to Manage Armored Scales (Hemiptera: Diaspididae) in Christmas Tree Plantations

Exploitative Competition Between Invasive Herbivores Benefits a Native Host Plant

Contact Info

Product

Resources

About