About

Tim Kring is an Emeritus Faculty member and the Department Head of Entomology at Virginia Tech. He holds a Ph.D. in Entomology from Texas A&M University, earned in 1984, and a B.S. in Biology from Quinnipiac University. His career includes positions at the University of Arkansas, where he served as a Professor from 1994 to 2016 and as an Emeritus Professor since 2016. Kring's research specializes in maximizing natural control of insect pests, with a focus on increasing reliance on beneficial insects within agricultural cropping systems. His work has involved biological control programs targeting pests in wheat, cotton, grain sorghum, and generalist predators across multiple systems. Additionally, he initiated a program in Virginia on biological control of invasive weeds, specifically spotted knapweed. Currently, his research assesses the role of biofuel crops as sources or sinks of beneficial insects and pollinators across agricultural and natural landscapes.

Research topics

• Ecology
• Biology

Selected publications

• Interactions Among Native and Non-Native Predatory Coccinellidae Influence Biological Control and Biodiversity

  Annals of the Entomological Society of America · 2020 · 38 citations

  • Biology
  • Ecology

  Abstract Over the past 30 yr, multiple species of predatory Coccinellidae, prominently Coccinella septempunctata L. and Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) have spread to new continents, influencing biodiversity and biological control. Here we review the mechanisms underlying these ecological interactions, focusing on multi-year field studies of native and non-native coccinellids and those using molecular and quantitative ecological methods. Field data from Asia show that H. axyridis, C. septempunctata, and Propylea japonica (Thunberg) (Coleoptera: Coccinellidae) are regularly among the most abundant predatory species but their rank varies by habitat. Studies of these species in their native Asian range, primarily related to their range in mainland China, document different patterns of seasonal abundance, species specific associations with prey, and habitat separation. Intraguild predation is well documented both in Asia and in newly invaded areas, and H. axyridis benefits most from this interaction. Harmonia axyridis also seems to rely more on cannibalism in times of prey scarcity than other species, and relatively sparse data indicate a lower predation pressure on it from natural enemies of coccinellids. Declines in the abundance of native coccinellids following the spread and increase of non-native species, documented in several multi-year studies on several continents, is a major concern for native biodiversity and the persistence of native coccinellid species. We suggest that future studies focus more attention on the community ecology of these invasive species in their native habitats.

  PublisherOA PDFDOI

• Establishment and Distribution of Laricobius spp. (Coleoptera: Derodontidae), a Predator of Hemlock Woolly Adelgid, Within the Urban Environment in Two Localities in Southwest Virginia

  Journal of Integrated Pest Management · 2019-01-01 · 18 citations

  articleOpen access

  Abstract Hemlock woolly adelgid (HWA), Adelges tsugae Annand, is a highly destructive non-native pest lethal to eastern hemlock, Tsuga canadensis (L.) Carrière, and Carolina hemlock, T. caroliniana Engelmann. Fifty years following the first observation of HWA in eastern North America, a predatory beetle, Laricobius nigrinus Fender, was evaluated, approved, and released as a biological control agent. Efforts were made to mass rear L. nigrinus with the goal of redistributing the beetles on public lands, typically in forest ecosystems, as a secondary option to silvicultural and chemical controls. The majority of L. nigrinus releases has occurred on public lands. Herein, we report the observation of L. nigrinus within the urban environment outside of known release locations. Two towns, Blacksburg and Radford, were divided into 0.40 km2 grids. A total of 27 and 19 grids were randomly selected from each town, respectively. Hemlocks were present in 44 and 42% of the grids surveyed in Blacksburg and Radford, respectively. In Blacksburg and Radford, 86 and 100% of the grids with hemlocks were infested with HWA, and of those infested hemlocks, Laricobius spp. was present in 100 and 75% of grids, respectively. A total of 154 Laricobius spp. (98% L. nigrinus and 2% Laricobius rubidus) adults were collected between each town. While it is unclear the level of control L. nigrinus has on reducing HWA's impact, the establishment of this biological control agent in the urban environment is an additional level of predation, that would otherwise not be present, for homeowners with HWA-infested trees.

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• Effects of Thiamethoxam-Treated Seed on Mexican Bean Beetle (Coleoptera: Coccinellidae), Nontarget Arthropods, and Crop Performance in Southwestern Virginia Snap Beans

  Environmental Entomology · 2017-10-09 · 4 citations

  articleOpen access

  Thiamethoxam is a neonicotinoid insecticide commonly applied directly to the seeds (seed-treatment) of commercial snap beans, Phaseolus vulgaris L. While previous studies have examined target and nontarget effects of thiamethoxam seed-treatments in snap beans and other crops, to our knowledge, none have been conducted in agroecosystems predominated by the pest Mexican bean beetle, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae). This study examined the effects of thiamethoxam-treated snap beans on E. varivestis, other arthropods, and crop performance in southwestern Virginia. Greenhouse experiments were conducted to evaluate residual toxicity of treated snap beans to E. varivestis and a key predator, Podisus maculiventris (Say) (Hemiptera: Pentatomidae). Treated plants were highly toxic to E. varivestis at 13 d, moderately toxic from 16 to 20 d, and minimally toxic at 24 d. P. maculiventris was unaffected by exposure to treated plants or by feeding on E. varivestis that consumed treated plants. Small plot field experiments in 2014 and 2015 showed no significant effects of thiamethoxam seed-treatments on E. varivestis densities, other arthropods, crop injury, or yield. In 2016, planting was delayed by persistent rain, resulting in early E. varivestis colonization. In this year, thiamethoxam-treated plants had significantly lower densities and feeding injury from E. varivestis, followed by significantly higher yields. Natural enemies were unaffected by seed-treatments in all field experiments. These experiments demonstrated that thiamethoxam seed-treatments provide control of E. varivestis when beetles infest fields within 2 to 3 wk after planting; but otherwise provide negligible advantages. Negative effects from thiamethoxam seed-treatments on nontarget arthropods appear minimal for snap beans in this region.

  PublisherOA PDFDOI

• <i>Larinus minutus</i>(Coleoptera: Curculionidae) and<i>Urophora quadrifasciata</i>(Diptera: Tephritidae), Evidence for Interaction and Impact on Spotted Knapweed in Arkansas

  Environmental Entomology · 2016-03-25 · 1 citations

  articleOpen access

  Interactions among seed-feeding insects are well noted in the literature, with many of these interactions being asymmetrical and causing a disadvantage for one of the species involved. While often effective, the use of the cumulative stress approach to biological control (where multiple natural enemy species are released) may increase the risk of interaction, which may lead to less effective biological control programs. Spotted knapweed (Centaurea stoebe ssp. micranthos (Gugler) Hayek) is an invasive plant that causes damage in rangelands and pastures. In Arkansas, two biological control agents for spotted knapweed, Larinus minutus Gyllenhal and Urophora quadrifasciata Meigen, are established. Both species attack the capitula of spotted and diffuse knapweeds. There is potential for interactions between these species, and this could affect the efficacy of the biological control program. To evaluate these potential interactions, we collected spotted knapweed capitula weekly from three sites in Arkansas from 2010 to 2012. Capitula were monitored for emergence of L. minutus and U. quadrifasciata, and the effect on seed reduction was analyzed. Over all three years, L. minutus and U. quadrifasciata were present in 35.8% (492) and 22.8% (313) of the capitula, respectively. We determined that the occurrences of L. minutus and U. quadrifasciata were not independent of each other, and that L. minutus is more effective at reducing spotted knapweed seed production than U. quadrifasciata within individual capitula. Seed production in capitula with both natural enemies present was no different from capitula with L. minutus.

  PublisherOA PDFDOI

• Spread of<i>Larinus minutus</i>(Coleoptera: Curculionidae), a Biological Control Agent of Knapweeds, Following Introduction to Northwestern Arkansas

  Florida Entomologist · 2016-12-01 · 1 citations

  articleOpen access

  Spotted knapweed, Centaurea stoebe L. (Asteraceae), is an invasive perennial forb that has become economically and ecologically damaging in North America. The weevil Larinus minutus Gyllenhal (Coleoptera: Curculionidae), a biological control agent of invasive knapweeds, was introduced to 37 sites in northwest Arkansas since 2008 as part of a biological control program for spotted knapweed. In 2011 and 2012, 25 of these release sites were surveyed to monitor how L. minutus infestation rates changed in relation to distance and time from release. The initial L. minutus introductions at these sites occurred from 2008 to 2011. Transects were used from the point of initial weevil introduction to establish sampling quadrats in which capitula were collected to document weevil presence and infestation rates. The mean maximum distance of weevil colonization and mean local abundance (within the first 50 m from the release point) were calculated in relation to time (yr) since release. Five sites had >10 quadrats in both sampling years and were analyzed with an exponential decay function to model localized population growth and spread. Annual increases in mean local abundance and maximum distance of colonization were observed. These results were substantiated by localized growth (at 3 sites) and spread (at 2 sites) that occurred at the 5 sites analyzed with the exponential decay function. These findings suggest that in years following L. minutus introduction, assuming similar release strategies and environmental conditions, consistent increases in weevil infestation rates and spread from the release site may be expected in about half the sites at which populations establish.

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• Release and Monitoring of<i>Larinus minutus</i>(Coleoptera: Curculionidae), a Biological Control Agent of Spotted Knapweed in Arkansas

  Florida Entomologist · 2014-06-01 · 5 citations

  articleOpen access

  Spotted knapweed (Centaurea stoebe ssp. micranthos (Gugler) Hayek) is an invasive plant from Eurasia that degrades pastures and rangelands in the western United States and Canada. A biological control program for spotted and diffuse (C. diffusa Lamarck) knapweeds was initiated in the 1960s, with 13 species of insects introduced and established in the United States and Canada. The program has largely been considered a success and Larinus minutus Gyllenhal (Coleoptera: Curculionidae) is considered to be one of the key agents responsible for the reduction of knapweeds. Spotted knapweed expanded its range into the southeastern United States, but biological control was not used against the weed in this region until recently. Larinus minutus were released in 6 counties in Arkansas from 2008 through 2012. Weekly sweep-net sampling to monitor weevil activity showed establishment of the weevils in 5 counties. The numbers of L. minutus captured at each site increased from 2010 to 2012. Larinus minutus in Arkansas was univoltine and sex ratios were 1:1, except during flowering, when the proportion of females captured increased. Eggs were not present in females until 1 week after flowering of spotted knapweed.

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• Mi-1.2, an R gene for aphid resistance in tomato, has direct negative effects on a zoophytophagous biocontrol agent, Orius insidiosus

  Journal of Experimental Botany · 2014-09-04 · 22 citations

  articleOpen access

  Mi-1.2 is a single dominant gene in tomato that confers race-specific resistance against certain phloem-feeding herbivores including aphids, whiteflies, psyllids, and root-knot nematodes. Few prior studies have considered the potential non-target effects of race-specific resistance genes (R genes), and this paper evaluates the compatibility of Mi-mediated resistance in tomato with a beneficial zoophytophagous predator, Orius insidiosus (Say). In addition to preying on aphids and other pests, this piercing-sucking insect also feeds from the xylem, epidermis, and/or mesophyll, and oviposits within plant tissues. Comparison of O. insidiosus confined to isogenic tomato plants with and without Mi-1.2 revealed that immatures of O. insidiosus had lower survival on resistant plants even when the immatures were provisioned with prey that did not feed on the host plant. Molecular gut content analysis confirmed that adults and immatures of O. insidiosus feed on both resistant (Mi-1.2+) and susceptible (Mi-1.2-) genotypes, and bioassays suggest that resistance does not affect oviposition rates, plant sampling, or prey acceptance by O. insidiosus adults. These results demonstrate a direct negative impact of R-gene-mediated host plant resistance on a non-target beneficial species, and reveal that Mi-mediated resistance can impact organisms that do not feed on phloem sap. Through laser capture microdissection and RT-PCR, Mi-1.2 transcripts were detected in the epidermis and mesophyll as well as the phloem of tomato plants, consistent with our observations that Mi-mediated resistance is active outside the phloem. These results suggest that the mode of action and potential ecological impacts of Mi-mediated resistance are broader than previously assumed.

  PublisherOA PDFDOI

• The role of rice stink bug in the transmission of Bacterial Panicle Blight in rice.

  2014-01-01

  article
  Publisher

• Determining the Efficacy of Larinus minutus (Coleoptera: Curculionidae) in Spotted Knapweed Biological Control: The Silver Bullet?

  2011-01-01

  article

  Spotted knapweed, Centaurea stoebe ssp. micranthos (Gugler) Hayek, is an exotic, invasive weed that has caused significant damage in the northwestern United States and can reduce forage production by more than 88%. In spite of a successful biological control program for this in the northwest, the weed is expanding rapidly throughout the southeastern United States, where no comprehensive control program exists. One of the insects thought largely responsible for the weed’s decline in the northwest is Larinus minutus Gyll. Adult L. minutus were collected from areas around Colorado Springs, Colorado, from 2007 through 2011. Adult weevils were returned to Arkansas and released at 39 sites at an average of 700 weevils per release. Studies to determine the effect of L. minutus on knapweed seed and plant densities were conducted in 2010 and 2011. The only differences in knapweed population variables at release and non-release sites were seed density and plant height. At weevil release sites, the number of seeds produced was significantly lower and the plants were significantly shorter. Other impacts on stands of spotted knapweed are likely to become evident after populations of L. minutus have had more time to increase.

  Publisher

• <i>Larinus minutus</i>(Coleoptera: Curculionidae), A Biological Control Agent of Spotted Knapweed (<i>Centaurea stoebe</i>ssp.<i>Micranthos</i>), Established in Northern Arkansas

  Florida Entomologist · 2011-06-01 · 5 citations

  articleOpen access

  Larinus minutus Gyllenhal (Coleoptera: Cur culionidae) is a univoltine weevil that feeds on the seeds of spotted and diffuse knapweeds Centau rea stoebe ssp. micranthos (Gugler) Hayek and C. diffusa Lamarck. After emerging from overwin tering sites in the leaf litter, adult weevils begin feeding on the vegetative portions of the plants. Adults, however, prefer to feed on flowers when they are available and development of beetle ova ries is dependent upon flower feeding (Groppe 1990). Females oviposit on newly opened flower heads (capitula). Two or 3 eggs can occur in each flower head, but only 1 larva usually develops in smaller capitula. Multiple larvae can survive in large spotted knapweed capitula (Groppe 1990). Under laboratory conditions (25°C), eggs hatch in 3-4 d (Groppe 1990). Larval development takes approximately 4 weeks and larvae go through 3 instars. Larvae feed on knapweed seeds and pu pate in the capitula, making a cocoon out of the seed head material (Kashefi & Sobhian 1998). Larvae can destroy up to 100% of the seeds in a capitulum (Kashefi & Sobhian 1998). In the West ern United States, adult weevils emerge in late Sep and feed on plants until winter, when the adults overwinter in leaf litter and emerge in the following Jun (Jordan 1995). Larinus minutus was first released into the United States in 1991 with collections from Greece and Romania (Story 2002). Although 12 other natural enemy species were introduced into the Western United States and Canada to control spotted and diffuse knapweeds, only recently has adequate suppression of some populations been seen (Myers 2004; Smith 2004). Myers (2007) sug gested that knapweed populations did not signif icantly decline until the establishment of L. minutus. Populations of L. minutus have been es tablished in Washington, Wyoming, Oregon, Mon tana, Minnesota, Colorado, and Indiana (Lang et al. 1996; Story 2002). No natural enemies of spotted knapweed have been released in Arkansas until the inception of this study. However, we found Urophora quadrifasciata (Meigen) (Diptera: Tephritidae) established throughout the range of spotted knapweed in the state in a survey in 2006 for knapweed natural ene mies. This seedhead galling fly was introduced from Russia into Canada in 1980 and has since been re distributed or spread on its own to several states in the northeastern and northwestern United States (Story 2002). Duguma (2008) found that U. quadri fasciata reduced the number of seeds produced by spotted knapweed by 44% late in the season (Aug), at a time when plants are more environmentally stressed. However, the fly did not significantly re duce the number of seeds produced earlier in the season, a time when knapweed is most robust (Du guma 2008). Thus, it is likely that U. quadrifasciata alone will not significantly suppress knapweed pop ulations in Arkansas, or stop its spread further into the southern United States.

  PublisherOA PDFDOI

Frequent coauthors

• John R. Ruberson

  University of Nebraska–Lincoln

  16 shared

• W. C. Yearian

  University of Arkansas at Fayetteville

  8 shared

• Donald C. Steinkraus

  University of Arkansas at Fayetteville

  8 shared

• S. Y. Young

  University of Arkansas at Fayetteville

  7 shared

• F. E. Gilstrap

  6 shared

• V. Bruce Steward

  DuPont (United States)

  6 shared

• James B. Kring

  5 shared

• Carey R. Minteer

  Smithsonian Marine Station

  5 shared

Labs

• Tim Kring LabPI

Education

• PhD, Entomology

  Texas A&M University

  1985

• MS, Entomology

  Texas A&M University

  1981

• BA, Biology

  Quinnipiac University

  1979