Lepidoptera-specific insecticide used to suppress gypsy moth outbreaks may benefit non-target forest Lepidoptera

Abstract

1 Despite considerable interest in the impacts of forest-defoliating insects and pesticide-based suppression of defoliator outbreaks on non-target arthropods, studies have often been hampered by the unpredictability of outbreaks. 2 We evaluated the long-term impacts of forest defoliation by gypsy moths, and the suppression of their outbreaks with Bacillus thuringiensis var. kurstaki (Btk), on native moths. Three years after a gypsy moth outbreak, moth diversity and abundance were compared among sites that were defoliated but not sprayed with Btk (defoliated sites), defoliated and sprayed (Btk sites) or neither (undisturbed sites). We conducted separate evaluations of the effects of disturbance history on the overall moth community, taxonomic subgroups (families) and moths differing in their dietary overlap with gypsy moths. 3 Analyses of the full moth community revealed no effects of disturbance history on local ( ) moth diversity or diversity of moths among sites ( -diversity). The -or -diversities of moths classified by their dietary overlap with gypsy moths (overlapping, partially overlapping, not overlapping) were also not affected by disturbance history. However, taxonomic affiliation was important. Geometridae -diversity in late summer was significantly lower in defoliated sites than in Btk or undisturbed sites. No effects of disturbance history on moth abundances were found. 4 We conclude gypsy moth defoliation had negative effects on a major moth family (Geometridae), although Btk application may have protected Geometridae from the adverse effects of gypsy moth defoliation. The results of the present study help to clarify the relative, and sometimes countervailing, effects of defoliators and microbial pesticides on forest communities.

Microbial pesticide application during defoliator outbreaks may reduce loss of regional forest beetle richness

“…These areas were selected based on their high cultural value and high densities of gypsy moth egg masses (National Park Service 2008). Though most of the area sprayed in spring 2008 was defoliated in the summer of the same year, there was very little defoliation in these sprayed areas in 2009, in contrast to much of the surrounding area, suggesting the Btk application had somewhat delayed effects on defoliation (Manderino et al 2014).…”

“…kurstaki (Btk), a Lepidoptera-specific bacterial pesticide that does not directly affect other taxa (McClintock et al 1995, Sample et al 1996, Rieske and Buss 2000. Several studies have addressed the effects of Btk application on the abundance and diversity of non-target forest Lepidoptera (Work and McCullough 2000, Rastall et al 2003, Boulton 2004, Manderino et al 2014 as well as indirect effects of Btk on the abundance of a limited number of Coleoptera families (Sample et al 1996, Rieske and Buss 2000, Rieske and Buss 2002, Strazanac and Butler 2005. However, potential indirect effects of Btk on the species diversity of arthropods other than Lepidoptera remain poorly understood.…”

“…The European strain of the gypsy moth (Lymantria dispar) has defoliated as much as 5.2 million hectares of forest in the United States in a single year (U.S. Forest Service Gypsy Moth Digest, http://www.na.fs.fed.us/fhp/gm/ defoliation). A number of studies examining the effects of gypsy moth defoliation and application of Btk to suppress gypsy moth populations have identified declines in species diversity and abundance of non-target Lepidoptera following both defoliation and pesticide application (Work and McCullough 2000, Boulton 2004, Manderino et al 2014. Effects of gypsy moth outbreaks, or their suppression, on insects other than Lepidoptera are less well known.…”

The Ecological and Evolutionary Consequences of Alien Invasive Species

“…Exploring the latter can be complex. The severe forest defoliations caused by outbreaks of Gypsy moth in North America occur in areas that support large numbers of native Lepidoptera, whose fate may be infl uenced by (1) the direct loss of foliage food and (2) indirect trends such as plant host defences induced by Gypsy moth feeding, so that the available foliage becomes less nutritious (Manderino et al 2014 ). Light trap sampling of moths in the Shenandoah National Park, Virginia, examined their richness and abundance 3 years after an outbreak between (1) sites that were defoliated but not treated with the pathogen Bacillus thuringiensis kurstacki , (2) defoliated and pathogen-treated sites, and (3) unaffected sites that were both undefoliated and unsprayed, in an effort to clarify the relative effects of defoliation and microbial pesticides on the forest moth communities.…”

Sequencing and de novo assembly of the Asian gypsy moth transcriptome using the Illumina platform

“…Subspecies of the gypsy moth occur in Europe, North Africa, Asia and North America (Manderino et al ., 2014). The ‘Asian form’ is characterized by females that fly actively, whereas only non-flying females are known in Europe and North America.…”