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The hemlock woolly adelgid, Adelges tsugae Annand, is an invasive pest of eastern (Tsuga canadensis (L.) Carrière) and Carolina hemlock (Tsuga caroliniana Engelmann) forests in the eastern United States. Scymnus (Pullus) coniferarum Crotch (Coleoptera: Coccinellidae) is a lady beetle that preys on A. tsugae in the western United States, where A. tsugae infestations on western hemlocks are not lethal. It is thought that S. coniferarum could be an important predator that helps keep A. tsugae populations from reaching damaging levels in this region. This study assesses the potential of this predator as a biological control agent for A. tsugae in the eastern United States. S. coniferarum predation, reproductive potential, and survival were evaluated in field-cages on adelgid-infested T. canadensis at two sites in southwestern Virginia. Sampling was conducted between December 2012 and June 2014 to evaluate the impact of S. coniferarum on both generations of A. tsuage (sistens and progrediens). Adult S. coniferarum fed on both generations and all life stages of A. tsugae during both field trials at rates comparable to other adelgid-specific predators. Evidence of S. coniferarum oviposition was minimal, and may be attributed to low temperatures and prey availability. S. coniferarum mortality was greatest when exposed to winter temperatures at the higher elevation site in 2013, and least throughout the 2014 spring sample period. S. coniferarum demonstrated a high predation rate on A. tsugae and survived for extended periods of time at sites in southwest Virginia, indicating that this species could be an effective predator of hemlock woolly adelgid in similar climates. [ABSTRACT FROM AUTHOR]

Coleopteran species are biological control agents of numerous invasive pests. Laricobius nigrinus (Coleoptera: Derodontidae), a predaceous, univoltine species, spends the summer aestivating but is active for the rest of the year. Laricobius nigrinus possesses many essential attributes for effective biological control of the hemlock woolly adelgid (Hemiptera: Adelgidae). The predator must be reared in large numbers for field releases. We describe some of the studies that led to the successful procedures currently used for mass rearing L. nigrinus. [ABSTRACT FROM AUTHOR]

The article focuses on a research conducted in order to examine the visual ability and the searching behavior of Laricobius nigrinus (L. nigrinus), a host-specific predator of the hemlock woolly adelgid, Adelges tsugae. It discusses the attempts of individual adults in locating an uninfested eastern hemlock seedling under either light or dark conditions with the help of laboratory bioassay. The study revealed the dependence of searching behavior of L. nigrinus on food abundance.

Hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an invasive pest of eastern hemlock (Tsuga canadensis (L.) Carrière) and Carolina hemlock (T. caroliniana Englem.) in eastern United States. Host-range tests for Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), imported from Japan, were conducted under quarantine in Blacksburg, VA, to determine the suitability of this predator as a biological control agent of A. tsugae. Host-range testing for L. osakensis, involved no-choice and paired choice feeding, oviposition, and development tests with A. tsugae, three other adelgids, and three nonadelgid species. L. osakensis fed and laid more eggs on A. tsugae over all the other host species. The difference was greater in paired-choice tests. L. osakensis completed development only on A. tsugae. The overall results of the host range study indicate that L. osakensis is a specific predator of A. tsugae, supporting its potential as a biological control agent, and is not a threat to nontarget species populations. [ABSTRACT FROM AUTHOR]

The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), native to western North America and Asia, was accidentally introduced from Japan to the eastern United States. To potentially establish biological control of A. tsugae, we released a predator endemic to western North America, Lavicobius nigrinus Fender (Coleoptera: Derodontidae), from 2003 to 2005, in 22 localities from Georgia to Massachusetts. Release sites spanned the invasive range of the adelgid across five United States Department of Agriculture plant hardiness zones (5a to 7a). Release sizes were 75, 150, 300, 600, or 1,200 adult L. nigrinus per site in the fall, winter, early spring, or sequentially (i.e., fall or winter and early spring). We monitored establishment by annual sampling for L. nigrinus adults with beat sheets and for L. nigrinus larvae by branch clipping. At the end of 3 yr, L. nigrinus was established in 13 of the 22 sites. The following variables were evaluated for their correlation with the numbers of L. nigrinus larvae and adults recovered and for their effect on establishment (scored as F3 presence/absence): (1) Minimum winter temperature at the release site, (2) A. tsugae density at the time of release, (3) release size, and (4) release season. Only minimum winter temperature was correlated with larval recoveries and no variables were correlated with adult recoveries. Logistic regression modeling found that establishment was positively related to minimum winter temperature and release size. We recommend smaller release sizes in warm areas where establishment probability was high (i.e., zones 7a, 6b, and 6a) and larger release sizes in cold areas where establishment probability was low (i.e., zones 5b and 5a). Releases during fall-early spring and across the range of A. tsugae densities tested were successful. [ABSTRACT FROM AUTHOR]

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Competitive interactions among two specialist predators, Laricobius nigrinus Fender and Sasajiscymnus (Pseudoscymnus) tsugae Sasaji and McClure, and a generalist predator, Harmonia axyridis Pallas, of hemlock woolly adelgid, Adelges tsugae Annand, were studied in the laboratory. The two specialist predators are part of a biological control program that has been initiated for A. tsugae, and the potential for competition among these species mad polyphagous established predators is unknown. Laboratory assays were evaluated in environmental chambers at two conditions: (1) early spring, 9:5°C (D:N), 12:12 (L:D) b, and 50–75% RH; and (2) late spring, 18:10°C (D:N), 16:8 (L:D) h, and 75–90% RH. Predator feeding trials using conspecific and heterospecific eggs showed that L. nigrinus and S. tsugae eggs were consumed by all species, and predation was decreased with increased A. tsugae density. Eggs of H. axyridis were eaten almost exclusively by conspecifics, at high rates, regardless of A. tsugae density. Survival, feeding on A. tsugae, and net egg production of single predators and groups of three conspecifics and heterospecifics were also examined. Survival for all species was not significantly affected by the presence of additional predators. In conspecific groupings, only H. axyridis showed significant reductions in feeding on A. tsugae, whereas all species bad significantly reduced net egg production with conspecifics. In heterospecific groupings, no significant effects on A. tsugae predation or net egg production were detected. The only significant negative competitive interactions detected in these assays were among conspecifics, whereas heterospecific combinations showed noninterference. [ABSTRACT FROM AUTHOR]

Laricobius rubidus LeConte, native to eastern North America whose primary host is Pineus strobi Hartig, has been observed in association with Adelges tsugae, an exotic and lethal pest of hemlock trees in eastern North America. Pineus strobi and A. tsugae were used to evaluate host preference and suitability of this predatory beetle to determine in part its suitability as a potential biological control agent of A. tsugae. In a paired-choice oviposition test, L. rubidus preferred to oviposit in P. strobi ovisacs over those of A. tsugae. However, in the no-choice oviposition test, there was no significant difference in the mean number of eggs laid by L. rubidus females in P. strobi or A. tsugae ovisacs. There were no significant differences in larval developmental time or survivorship for L. rubidus reared on a diet of either P strobi or A. tsugae. Laricobius rubidus completed development to the adult stage on A. tsugae indicating that it is a suitable host and therefore has the potential to contribute to biological control of A. tsugae in the eastern United States. The introduction of a congener, Laricobius nigrinus to eastern North America may result in competition with L. rubidus on A. tsugae, but the inability of L. nigrinus to complete development on P strobi suggests that the two congeners will not compete on the primary host of L. rubidus. [ABSTRACT FROM AUTHOR]

The pales weevil, Hylobius pales (Herbst) (Col., Curculionidae) is an important regeneration pest of Pinus seedlings and a secondary pest of Christmas tree plantations in the United States. Attempts to sample this endemic pest in Virginia, USA with simulated host odors of ethanol and turpentine have met with varying levels of success. Mark-and-recapture techniques were used to assess the efficacy of various combinations of host volatiles, pine billets, and trap designs for capturing H. pales adults. No differences were observed in the number of H. pales caught between pit and PVC pitfall traps containing the same bait type. Traps containing freshly cut Pinus strobus L. billets caught significantly more weevils than traps containing synthetic volatiles alone. Traps baited with freshly cut P. strobus caught significantly more weevils than those containing P. strobus cut 2 months previously. The synthetic attractant components of ethanol and turpentine were most effective when presented in a combined bait blend than when released from separate vials. Overall, traps baited with combined blends of 5:1 ethanol-turpentine and freshly cut P. strobus were most effective in capturing H. pales. Hylobius pales showed no attraction to unbaited PVC pitfall or pit traps. Males and females responded similarly to all treatments. [ABSTRACT FROM AUTHOR]

Four species of pine-root feeding weevils, Hylobius radicis Buchanan, H. assimilis Boheman, H. pales (Herbst), and Pachylobius picivorus (Germar), comprise a major pest guild on plantation pines in the Great Lakes region. The former 2 species breed in living trees, whereas the latter 2 species breed in dead or dying trees or stumps. This study develops an ecological and physiological context for the diversity of responses to a common chemical signal among closely related species exploiting common hosts. All 4 species respond to a mixture of terpenes and ethanol but show different temporal and behavioral patterns.H. radicis and H. assimilis have a spring peak and midsummer declinein attraction to turpentine- and ethanol-baited pitfall traps, and females are the predominant gender captured. The period of attraction of H. pales and P. picivorus to baited traps extends somewhat later into the summer, and males and females are captured in equal numbers. For all species, capture rates in passive screen traps decline later than those in pitfall traps. Dissections of captured female weevils show that volatile- emitting pitfall traps are selective for reproductively mature individuals of all species, whereas the passive screen traps catch nonreproductive and reproductive females in equal numbers.Ninety-seven percent of the males captured were reproductively mature, so their decline in attraction to pitfall traps is not directly related to reproductive status. Niche differences among the 4 species can explain some of the differences inb the attraction of weevils to baited pitfall traps. [ABSTRACT FROM AUTHOR]