Deepa S PureswaranNatural Resources Canada | NRCan · Canadian Forest Service - Atlantic Forestry Centre
Deepa S Pureswaran
PhD, Biological Sciences
About
72
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Introduction
Skills and Expertise
Additional affiliations
March 2008 - present
January 2006 - October 2007
July 2004 - December 2005
Education
September 1999 - November 2003
September 1997 - August 1999
Publications
Publications (72)
The geographical exchange of non-native insects can be highly asymmetrical, with some world regions 'exporting' or 'importing' more species than others. Several hypotheses have been proposed to explain such asymmetries, including differences in propagule pressure, environmental features in recipient regions, or biological traits of invaders. We tes...
Invasive species are leading causes of biodiversity loss and economic damage. Prevention and management of invasions requires risk assessments based on ecological knowledge for species of potential concern. Interactions between introduced species and heterospecifics in the recipient community may affect the likelihood of establishment through bioti...
Globalization and economic growth are recognized as key drivers of biological invasions. Alien species have become a feature of almost every biological community worldwide, and rates of new introductions continue to rise as the movement of people and goods accelerates. Insects are among the most numerous and problematic alien organisms, and are mai...
Aim: Lepidoptera is a highly diverse, predominantly herbivorous insect order, with species transported to outside their native range largely facilitated by the global trade of plants and plant-based goods. Analogous to island disharmony, we examine invasion disharmony, where species filtering during invasions increases systematic compositional diff...
Top-down effects, like predation, are drivers of insect outbreaks, but bottom-up effects, like host nutritional quality, also influence outbreaks and could in turn be altered by insect-caused defoliation. We evaluated the prediction that herbivory leads to a positive feedback on outbreak severity as nutrient concentration in plant tissues increases...
Tetropium fuscum (Coleoptera: Cerambycidae) is a Eurasian longhorn beetle and forest pest that first became invasive to Nova Scotia, Canada around 1990. In the time since its introduction, T. fuscum has spread only about 150 km from its point of introduction. In its invasive range, T. fuscum co-exists with its congener Tetropium cinnamopterum . Alt...
Bark and ambrosia beetles are highly successful invaders because of their life history, habits, and propensity to be easily transported by anthropogenic activities. Globalization and climate change interact to facilitate the movement of many species across and among continents, contributing to wide range expansions. Consequently, some species are t...
Aim
The concept of “island disharmony” has been widely applied to describe the systematic over- and under-representation of taxa on islands compared to mainland regions. Here, we explore an extension of that concept to biological invasions. We compare biogeographical patterns in native and non-native beetle (Coleoptera) assemblages from around the...
As part of national biosecurity programs, cargo imports, passenger baggage and international mail are inspected at ports of entry to verify compliance with phytosanitary regulations and to directly intercept potentially damaging non‐native species to prevent their introduction. Detection of organisms during inspections may also provide crucial info...
Phenological shifts, induced by global warming, can lead to mismatch between closely interacting species. The eastern spruce budworm, Choristoneura fumiferana, an important outbreaking insect defoliator in North America, mainly feeds on balsam fir, Abies balsamea, which has historically been well synchronized with the insect. But as climate change...
We investigated geographic variation in the semiochemistry of major disturbance agents of western North American pine forests, Dendroctonus brevicomis Le Conte and Dendroctonus barberi Hopkins (Coleoptera: Curculionidae: Scolytinae), species separated by the Great Basin in the USA that until recently were synonymous. At 15 sites in the western USA...
Insects are abundant nearly everywhere on earth and provide services important to ecosystem health (e.g., decomposition, seed dispersal) and the economy (e.g., pollination, crop pests). Understanding how climate change affects insects is necessary to predict changes in insect communities and the services they provide. Insect life history traits suc...
Toughness of leaves is an important defense mechanism of plants against insect
herbivores and is generally linked to leaf fibre content. We explored the anatomical
basis and ecological role of needle toughness as a mechanism of defense against
feeding initiation by second instar spruce budworm (Choristoneura fumiferana)
emerging from diapause. We f...
Re: Carleton RD, Owens E, Blaquière H, Bourassa S, Bowden JJ, Candau J-N, DeMerchant I, Edwards S, Heustis A, James PMA, Kanoti AM, MacQuarrie CJK, Martel V, Moise ERD, Pureswaran DS, Shanks E, and Johns RC. 2020. Tracking insect outbreaks: a case study of community-assisted moth monitoring using sex pheromone traps. FACETS 5: 91–104. doi.org/10.11...
Prior research from trapping experiments using synthetic pheromone components suggested the existence of local and geographical variation in the pheromone system of the spruce beetle, Dendroctonus rufipennis (Kirby). To test hypotheses concerning variation in the spruce beetle’s aggregation pheromone blend, we extracted volatiles from the hindguts...
Disturbance regimes are changing in forests across the world in response to global climate change. Despite the profound impacts of disturbances on ecosystem services and biodiversity, assessments of disturbances at the global scale remain scarce. Here, we analyzed natural disturbances in boreal and temperate forest ecosystems for the period 2001–20...
Insect outbreaks can cover vast geographic areas making it onerous to cost-effectively monitor populations to address management or ecological questions. Community science (or citizen science), which entails engaging the public to assist with data collection, provides a possible solution to this challenge for the spruce budworm (Choristoneura fumif...
1. Competitive and synergistic interactions directly or indirectly drive community dynamics of herbivorous insects. Novel interactions between non‐native and native insects are unpredictable and not fully understood. 2. We used manipulative experiments on mature red spruce trees to test interactions between a non‐native phloem feeding insect, the b...
Phenology has become a field of growing importance due to the increasingly apparent impacts of climate change. However, the time-consuming, subjective and tedious nature of traditional human field observations have hindered the development of large-scale phenology networks. Such networks are rare and rely on time-lapse cameras and simplistic color...
The spruce budworm, Choristoneura fumiferana, Clem., is the most significant defoliating pest of boreal balsam fir (Abies balsamea (L.) Mill.) and spruce (Picea sp.) in North America. Historically, spruce budworm outbreaks have been managed via a reactive, foliage protection approach focused on keeping trees alive rather than stopping the outbreak....
Climate change is predicted to alter relationships between trophic levels by changing the phenology of interacting species. We tested whether synchrony between two critical phenological events, budburst of host species and larval emergence from diapause of eastern spruce budworm, increased at warmer temperatures in the boreal forest in northeastern...
Dendroctonus rufipennis (Kirby, Coleoptera: Curculionidae) uses pheromone blends containing aggregative components (frontalin, verbenene, 1-methyl-2-cyclohexen-1-ol [MCOL], and seudenol) and an anti-aggregative component (3-methyl-2-cyclohexen-1-one [MCH]) to coordinate attacks against host trees, but little is known about the influence of external...
Purpose of Review
Climate change affects populations of forest insect pests in a number of ways. We reviewed the most recent literature (2013–2017) on this subject including previous reviews on the topic. We provide a comprehensive discussion of the subject, with special attention to insect range expansion, insect abundance, impacts on forest ecosy...
1.As major alterations are occurring in climate and pest ranges, it is imperative to evaluate their combined contribution to tree mortality in order to propose mitigation measures and limit losses in forest productivity. The objective of this study was to explore the association between declines in tree growth resulting from climatic and biotic (sp...
Tetropium fuscum (Fabricius) (Coleoptera: Cerambycidae), a phloem-feeding and wood-boring beetle introduced from Eurasia, attacks spruce in eastern Canada alongside its native congener Tetropium cinnamopterum Kirby. We reared phloem- and wood-feeding insects (and their predators) from bolts of red and Norway spruce (Picea rubens and Picea abies) in...
Establishing feeding sites is critical for the survival of neonate Lepidoptera larvae. Rapid foliar quality changes during leaf expansion create a narrow window of opportunity for establishment of early-spring feeders. We examined the effect of phenological synchrony between black spruce (Picea mariana (Mill.) B.S.P.) and balsam fir (Abies balsamea...
Many populations are thought to be regulated, in part, by their natural enemies. If so, disruption of this regulation should allow rapid population growth. Such “enemy escape” may occur in a variety of circumstances, including invasion, natural range expansion, range edges, suppression of enemy populations, host shifting, phenological changes, and...
Phenological mismatch has been proposed as a key mechanism by which climate change can increase the severity of insect outbreaks. Spruce budworm (Choristoneura fumiferana) is a serious defoliator of North American conifers that feeds on buds in the early spring. Black spruce (Picea mariana) has traditionally been considered a poor-quality host plan...
Plant neighborhood effects on herbivore damage have been observed in many systems although few studies have assessed the different component effects of the neighborhood (conspecific neighbors vs. heterospecific neighbors) on defoliation. No earlier studies have monitored how temporal scale influences neighborhood effects. We tested hypotheses on re...
Three main hypotheses have been postulated over the past century to explain the outbreaking population dynamics of eastern spruce budworm, Choristoneura fumiferana (Clemens). The Silviculture Hypothesis first arose in the 1920s, with the idea that outbreaks were driven by forestry practices favoring susceptible softwood species. In the 1960s, it wa...
We examined the native community of insects interacting with an invasive species, Tetropium fuscum (F.) (Coleoptera: Cerambycidae), in its new range to explore reasons for the invader’s relatively slow spread. Tetropium fuscum is a European spruce borer established in Nova Scotia since at least 1990, but it has spread only about 125 km from its sit...
We compared pheromone production and response for populations of western pine beetle, Dendroctonus brevicomis LeConte, from sites in northern Arizona and northern California. Volatiles were collected from individuals of both sexes that had mined as a pair in a Pinus ponderosa log for 1 d, and they were subsequently analyzed by gas chromatography co...
When related species coexist, selection pressure should favor evolution of species recognition mechanisms to prevent interspecific pairing and wasteful reproductive encounters. We investigated the potential role of pheromone and acoustic signals in species recognition between two species of tree-killing bark beetles, the southern pine beetle,Dendro...
Climate change is altering insect disturbance regimes via temperature-mediated
phenological changes and trophic interactions among host trees, herbivorous insects, and their
natural enemies in boreal forests. Range expansion and increase in outbreak severity of forest
insects are occurring in Europe and North America. The degree to which northern f...
As of summer 2014, the invasive emerald ash borer (EAB),
Agrilus planipennis
Fairmaire (Coleoptera: Buprestidae), has become established in 24 states in the United States of America and has killed tens of millions of ash trees since its introduction into Michigan in the 1990s. Considerable research has been conducted on many aspects of EAB life his...
The strength of interactions between individual host plants and their herbivores are influenced by identity of neighboring plants. These associational effects are expressed as either increased (associational vulnerability) or decreased (associational resistance) herbivore attack on the focal host plant. Phylogenetic proximity plays an important rol...
Different mechanisms mediate host selection by insects before (pre‐alighting) versus after (post‐alighting) landing on potential hosts, but few studies distinguish pre‐ and post‐alighting behaviour, particularly for wood borers.This study evaluates pre‐ and post‐alighting host selection by Tetropium fuscum (F.) (Coleoptera: Cerambycidae), a Palearc...
It is well understood that forces from multiple trophic levels simultaneously influence herbivore performance, but how the relative strength of these forces vary over space and time is less clear. We evaluated seasonal variation in the impact of bottom-up forces (host condition), top-down forces (natural enemies), and competition on the performance...
Allee effects can cause populations to decline due to decreasing population growth rates with decreasing density and play a major role in population dynamics. Mate‐finding failure, a common mechanism contributing to demographic Allee effects, is usually difficult to demonstrate because of the arduous nature of sampling individuals at very low densi...
We collected, identified, and quantified volatiles arising from individual gallery entrances of the monogamous bark beetle Dendroctonus frontalis Zimmermann. Samples were collected while the insects were mass attacking mature loblolly pines (Pinus taeda L.) in an established infestation in western Mississippi, 1 August through 3 October 2005. Follo...
Tetropium fuscum (F.) attacks weakened Norway spruce, Picea abies (L.) Karst., in its native Europe and may colonize healthy spruce in Nova Scotia, Canada. We used manipulative field experiments to evaluate: 1) the development of T. fuscum on apparently healthy red spruce (Picea rubens Sarg.) in Nova Scotia; 2) the influence of red spruce physiolog...
Many bark beetle species have similar life histories and aggregation pheromones, but often segregate temporally or spatially within trees or habitats. However, in Arizona several Dendroctonus species are known to colonize trees and occupy phloem resources in the same area of the tree bole. We investigated whether acoustic calls are distinct between...
We tested the hypothesis that nonhost conifers contain compounds that repel coniferophagous bark beetles (Coleoptera: Scolytidae) during host selection in four experiments (n = 10) involving paired trees baited with aggregation pheromones. Mountain pine beetles, Dendroctonus ponderosae Hopkins, and Douglas-fir beetles, Dendroctonus pseudotsugae Hop...
We studied the host selection behavior and feeding preference of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). A. planipennis is an exotic forest insect pest native to Asia that was discovered in North America in 2002 and is causing widespread mortality of ash trees (Fraxinus spp.) in southeast Michigan and surroun...
In field experiments at three sites in Michigan and Ohio we tested the activity of 1-octen-3-ol in combination with ipsdienol, the aggregation pheromone of the pine engraver, Ips pini (Say). When 1-octen-3-ol was added to funnel traps baited with ipsdienol, significantly fewer beetles of either sex were captured than in traps baited with ipsdienol...
The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive species recently established in North America. In large arena bioassays, when given a choice among live green ash, Fraxinus pennsylvanica Marsh and artificial ash saplings that were hidden or exposed from view, beetles preferred live trees (either visible...
The superiority of the host monoterpene myrcene as a synergist for trans-verbenol and exo-brevicomin, aggregation pheromone components of the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), suggests that the ancestral host of the mountain pine beetle is a pine rich in myrcene. A field trapping experiment in Britis...
We investigated the relative importance of olfaction versus vision in the mate-finding behavior of Agrilus planipennis. When coupled in male–female, male–male and female–female pairs, attempts to mate occurred only in the male–female pairs,
suggesting that beetles can identify the opposite sex before attempting to mate. In a set of sensory deprivat...
The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Bu- prestidae), is a highly destructive exotic pest of ash (Fraxinus) in North America. Human movement of infested logs, primarily pieces of firewood, is a major pathway for long distance spread of the beetle. Firewood may be confiscated at campgrounds, rest-areas, and key transporta...
Subtle differences in pheromone components of sympatric species should be attractive only to the producing species and unattractive or repellent to the nonproducing species, and thereby maintain reproductive isolation and reduce competition between species. Bark beetles Dendroctonus brevicomis and D. frontalis (Coleoptera: Curculionidae) are known...
Aggregation via pheromone signalling is essential for tree-killing bark beetles to overcome tree defenses and reproduce within hosts. Pheromone production is a trait that is linked to fitness, so high individual variation is paradoxical. One explanation is that the technique of measuring static pheromone pools overestimates true variation among ind...
Previous research indicated that the aggregation pheromone of the southern pine beetle, Dendroctonus frontalis, is produced only by females, the sex that initiates attacks. We provide evidence indicating that secondarily arriving males augment mass aggregation by releasing the attractive synergist (+)-endo-brevicomin. Healthy pines artificially inf...
Timing of arrival at a resource often determines an individual's reproductive success. Tree-killing bark beetles can reproduce in healthy trees by attacking in adequate numbers to overcome host defences that could otherwise be lethal. This process is mediated by aggregation and antiaggregation pheromones. Beetles that arrive early in such a "mass a...
Abstract 1 Synthetic blends of bole and foliage volatiles of four sympatric species of conifers were released from pheromone-baited multiple-funnel traps to determine if three species of tree-killing bark beetles (Coleoptera: Scolytidae): (i) exhibited primary attraction to volatiles of their hosts and (ii) discriminated among volatiles of four sym...
Eighteen monoterpenes found in bole and foliage volatiles of four sympatric species of conifers, Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, lodgepole pine, Pinus contorta var. latifolia Engelm., interior spruce, Piceaengelmannii×glauca, and interior fir, Abieslasiocarpa×bifolia, in three locations in British Columbia, Canada, were analysed...
Nine compounds identified from captured volatiles of the Douglas-fir beetle, Dendroctonus pseudotsugae, the mountain pine beetle, D. ponderosae, and the spruce beetle, D. rufipennis, that elicited antennal responses in males and females of one or more of these species were tested in the field to determine behavioural activity. 1-Octen-3-ol, found i...
Host selection in tree-killing bark beetles
(Coleoptera: Scolytidae) is mediated by a complex of semiochemical
cues. Using gas chromatographic-electroantennographic
detection (GC-EAD) and GC-mass spectrometric
analyses, we conducted a comparative study of the electrophysiological
responses of four species of tree-killing bark
beetles, the Douglas-f...
When released from attractant-baited multiple-funnel traps, 3-methyl-2-cyclohexen-1- one (MCH) reduced catches of male and female mountain pine beetles, Dendroctonus ponderosae Hopkins, by 67.4% and 71.8%, respectively. 2-Phenyl ethanol reduced the respective catches by 96.6% and 95.1%, but only verbenone and all three compounds together reduced ca...
Reproductive success in the mountain pine beetle, Dendroctonus ponderosae Hopkins, is determined by the production of aggregation and antiaggregation pheromones, as well as body size. In a laboratory experiment with beetles that emerged from naturally attacked hosts, there was no relationship between body size and the production of aggregation pher...
We tested the hypothesis that nonhost conifers contain compounds that repel coniferophagous bark beetles (Coleoptera: Scolytidae) during host selection in four experiments (n = 10) involving paired trees baited with aggregation pheromones. Mountain pine beetles, Dendroctonus ponderosae Hopkins, and Douglas-fir beetles, Dendroctonus pseudotsugae Hop...
The mountain pine beetle, Dendroctonus ponderosae Hopkins, and the pine engraver, Ips pini (Say), often co-exist in lodgepole pine, Pinus contorta var. latifolia Engelmann. Intra- and interspecific semiochemical communication occurs in both species and their complete semiochemical repertoire
and precise dynamics of pheromone production have not bee...
Projects
Projects (2)
This project is geared towards developing an area-wide management program to contain the spread of an ongoing spruce budworm outbreak in eastern Canada.
Key aspects of this expansive collaborative project include studies on population ecology, moth dispersal dynamics, community outreach and education (e.g., via the Budworm Tracker community science program), potential non-target impacts, as well as large-scale experiments to test the efficacy of the approach.