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Eurasian seed-head weevils, Larinus obtusus Gyllenhal and Larinus minutus Gyllenhal (Coleoptera: Curculionidae), were released annually from 2004-2013 across Wisconsin for biological control of the invasive forb spotted knapweed ( Centaurea stoebe L. ssp. micranthos (Gugler) Hayek). In 2014, Larinus spp. presence/absence surveys were conducted at 18 previous releases sites between 7/18/2014 – 8/16/2014 from 2007 (n=3), 2008 (n=3), 2009 (n=3), 2010 (n=6), 2011 (n=1) and 2012 (n=2). We found a significant, linear relationship between time since release and the natural log of the observed dispersal rates of Larinus spp. (F 1,10 = 18.8, P = 0.002, R 2 = 0.65), suggesting an increasing dispersal rate through time. Modeled result suggested the following relationship: LN (Dispersal distance in km) = 0.258*time since release + 0.741. Because the model intercept (i.e. dispersal rate) did not pass through zero at age zero, which was expected from a biological basis, I warn against extrapolating the modeled dispersal rate to the period from release (t=0) to the end of Year One. Applying these dispersal rates to all 326 previous Larinus spp. releases in Wisconsin we predict that by 2017 low level populations of Larinus spp could be found state-wide.

The morphology of two introduced knapweed feeders Larinus obtusus Gyllenhal, 1835 and Larinus minutus Gyllenhal, 1835 is investigated. The external and internal morphological characters are described for both sexes. The most promising discriminative characters including male and female terminal segments and genitalia structure are illustrated.

Introductions of biological control agents are unique field experiments to examine the response of novel organisms to new environments. Post-release monitoring is particularly challenging where closely related and morphologically similar biological control agents have been released. Two closely-related phytophagous weevils, Larinus minutus and L. obtusus, were introduced as biological control agents for two major rangeland weeds, diffuse knapweed, Centaurea diffusa and spotted knapweed, C. stoebe subsp. micranthos in North America. The release of the Larinus species coincided with a decline in C. diffusa abundance in many areas. However, it was not clear whether both species of Larinus had become established as they are morphologically very similar. We asked: (1) Could genetic markers be used to identify both the weevil species? (2) Do both weevil species attack both knapweed species in Canada? (3) Are the levels of genetic diversity of the introduced populations of the weevils similar to those of a European source population? (4) Is genetic mixing between the weevil species occurring? Both microsatellite and CO1 mtDNA markers distinguish between the two weevil species. Larinus obtusus was only found on spotted knapweed, while L. minutus was more widely distributed and attacked both weed species. The relatively large initial introductions of weevils to British Columbia (4,300 L. minutus and 5,500 L. obtusus) together with rapid population growth and frequent redistribution among sites has been sufficient to maintain levels of genetic diversity. Results from small samples showed that haplotype, nucleotide diversity and allelic richness of the introduced populations were comparable to those of a European population. We found no evidence for hybridization in the introduced populations.

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. USDA-APHIS-PPQUnited States Department of Agriculture (USDA) We thank Edward Gbur Jr. and Fred Stephen for their input on experimental design, and Elizabeth Long for her feedback on the manuscript. This work was supported in part through a Cooperative Agreement with USDA-APHIS-PPQ.

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.

Larinus (Larinomesius) minutus Gyllenhal (fig. 85) Larinus minutus Gyllenhal, 1835 Records. CRI* ČER ČRK* DNI DON KHE* KHM* KHR KRO* LUG ODE* POL ZAK ZAP* ŽIT* [ Lukjanovitch 1928: 250; Penecke 1932: 351; Shapiro 1940a: 52; Medvedev 1950b: 77; Kharakoz 1955: 15; Barsov et al. 1998: 150; Mazur 2002: 231 ]. Distribution. South Europe, West Asia; introduced to North America (G��ltekin & Fremuth 2013). Material examined. 143 specimens (ZIN, SIZK, KUMN, NSPU, ZMUM, IMC) from 15 provinces were studied. Cherkasy Prov.: 3 spec. (ZMUM) Korsun-Shevchenkivskyi, bank of Dnieper River, on Centaurea arenaria, Ter-Minasian leg., 23.vii.1933; 1 spec. (ZMUM) Cherkasy Distr., Verguny, A.F. Kryshtal leg., 8.vi.1946; Crimea: 1 spec. (KUMN) Rybachye near Alushta, S.I. Medvedev leg., 21.vii.1972; 2 spec. (KUMN) Yedi Quyu Distr., 21.vii.1972; 1 spec. (SIZK) Armyansk, S. V. Volovnik leg., 12.v.1983; 1 spec. (SIZK) Simferopol, A. Bazhenov, 19.vi.1899; 2 spec. (ZIN) Kerch, Kirichenko leg., 10.v.1902; 1 spec. (ZIN) İsl��m Terek Distr., Agarmish Mt., Kirichenko leg., 9.vi.1906; 1 spec. (ZIN) Shchebetovka [= Otuzi]. near Feodosia, Kirichenko leg., 18.vi.1901; 1 spec. (IMC) Bilohirsk Distr., Karasivka, I. V. Maltsev leg., 21.vii.1976; 1 spec. (IMC) Saky Distr., Skvortsivka, I. V. Maltsev leg., 1.vi.1954; 1 spec. (SIZK) Yedi Quyu Distr., Kazantip Cape, S. V. Volovnik leg., 18.v.1983; 3 spec. (SIZK) Bilohirsk Distr., Grushivka, 11.vi.1957; Kherson Prov.: 4 spec. (SIZK) Kherson, Potemkinsky Island, 3.viii.1966; 1 spec. (ZIN) Tsiurupynsk (= Alyoshky), lower of Dnieper River, D. Znoyko leg., 22.vii.1926; 1 spec. (IMC) Kherson, Maly Potemkinsky Island, Rafalsky leg., 22.vii.1964; Khmelnytskyi Prov.: 1 spec. (ZIN) Kamianets-Podilskyi, V. & I. Jakubowskij leg., 1905) Yelisavetgrad (= Kropyvnytsyi), Jacentkowskij leg., 1903; Odesa Prov.: 1 spec. (ZIN) Kodyma, G. Bazhenov, 19.vi.1902; 1 spec. (IMC) Odesa, Otrada Beach, I. V. Maltsev leg., 25.vi.1970; 1 spec. (IMC) Savransky Distr., Polyanetske, I. V. Maltsev leg., 25.vi.1970; 1 spec. (SIZK) Ovidiopol Distr., Bugaz, V. S. Solodovnikova leg., 21.vi.1966; 3 spec. (SIZK) Bilhorod-Dnistrovskyi Distr., Manashi, glade in woodland, 14.vi.1966; Zaporizhia Prov.: 1 spec. (FRC) Zaporizhia, S.I. Alexeenko, 7���8.v.2010; Zhytomyr Prov.: 6 spec. (IMC) Malin, on Centaurea, A. Bogachev leg., 6.vii.1944. Biology. Primary steppes, ruderal habitats. Adults occur in V���IX. Oligophagous on Centaurea spp. (Asteraceae) (Groppe 1990; Volovnik 1996a)., Published as part of Yunakov, Nikolai, Nazarenko, Vitalij, Filimonov, Rostislav & Volovnik, Semyon, 2018, A survey of the weevils of Ukraine (Coleoptera: Curculionoidea), pp. 1-494 in Zootaxa 4404 (1) on pages 384-385, DOI: 10.11646/zootaxa.4404.1.1, http://zenodo.org/record/3766751, {"references":["Gyllenhal, L. (1835) [new taxa]. In: Schoenherr, C. J., Genera et species curculionidum, cum synonymia hujus familiae. Species novae aut hactenus minus cognitae, descriptionibus a Dom. Leonardo Gyilenhal, C. H. Boheman, el entomologis aliis illustratae. Tomus tertius. - Pars prima. [1836], Roret, Parisii and Fred. Fleischer, Lipsia, 505 pp. https: // doi. org / 10.5962 / bhl. title. 8952","Lukjanovitch, Th. K. (1928) Spisok Cleoninae Poltavskoy gubernii (Coleoptera, Curculionidae). Zbirnyk Poltavskogo derzhavnogo muzeiu, 1, 1 - 4. [in Russian]","Penecke, K. A. (1932) Die Curculioniden (Russelkafer) Fauna der Bucovina. Nachtrage und Berichtigungen. Buletinul Facultatii de Stiinte din Cernauti, 5 (2) [1931], 347 - 356.","Shapiro, D. S. (1940 a) Entomofauna travianogo pokrova opushek polezashchitnykh polos. Trudy nauchno-issledovatelskogo zoologo-biologicheskogo instituta Kharkovskogo gosudarstvennogo universiteta. Sektor ekologii, 8, 47 - 67. [in Russian]","Medvedev, S. I. (1950 b) K voprosu o proiskhozhdenii entomofauny parkov Askanii-Nova. Trudy nauchno-issledovatelskogo instituta biologii Kharkovskogo gosudarstvennogo universiteta, 14 (15), 67 - 88. [in Russian]","Kharakoz, A. V. (1955) Entomofauna travianistogo pokrova Veliko-Anadolskogo lesa. Nauchnye zapiski Dnepropetrovskogo universiteta, 48, 151 - 164. [in Russian]","Barsov, V. A., Smirnov, M. E. & Antonets, N. V. (1998) Materialy k inventarizatsii zhestkokrylykh Dneprovsko-Orelskogo zapovednika. In: Rol okhoroniuvanykh pryrodnykh terytorii u zberezhenni bioriznomanittia. Fitosociocenter, Kaniv, pp. 146 - 151.","Mazur, M. (2002) The distribution and ecology of weevils (Coleoptera, Nemonychidae, Attelabidae, Apionidae, Curculionidae) in western Ukraine. Acta zoologica cracoviensia, 45 (3), 213 - 244.","Gultekin, L. & Fremuth J. (2013). Tribe Lixini. In: Lobl, I. & Smetana, A. (Eds.), Catalogue of Palaearctic Coleoptera. Vol. 8. Brill, Leiden, pp. 456 - 472. https: // doi. org / 10.1163 / 9789004259164","Groppe, K. (1990) Larinus minutus Gyll. (Coleoptera: Curculionidae), A Suitable Candidate for the Biological Control of Diffuse and Spotted Knapweed in North America. CABI Institute of Biological Control, Delemont, 30 pp.","Volovnik, S. V. (1996 a) Distribution and ecology of some species of Cleoninae (Coleoptera, Curculionidae) III. Genus Larinus Germ. Entomologicheskoe Obozrenie, 1995, 74 (2), 314 - 321. [in Russian, translated in Entomological Review, 75 (1), 10 - 19]"]}

highlights � Elevated CO2 (but not temperature) increased plant fitness but also agent density. � Biological control agent thus tempered positive CO2 effect on plant fitness. � Both elevated CO2 and temperature hastened plant phenology. � Faster plant phenology under elevated CO2 made plants more attractive to agents. � Plant and agent phenologies may be better matched with climate change. graphical a bstract abstract Predicted increases in atmospheric CO2 and temperature may benefit some invasive plants, increasing the need for effective invasive plant management. Biological control can be an effective means of managing invasive plants, but the anticipated range in responses of plant-insect interactions to climate change make it difficult to predict how effective biological control will be in the future. Field experiments that manipulate climate within biological control systems could improve predictive power, but are challeng- ing to implement and therefore rare to date. Here, we show that free air CO2 enrichment in the field increased the fitness of Centaurea diffusa Lam., a problematic invader in much of the western United States. However, CO2 enrichment also increased the impact of the biological control agent Larinus minutus (Coleoptera: Curculionidae) on C. diffusa fitness. C. diffusa plants flowered earlier and seed heads devel- oped faster with both elevated CO2 and increased temperature. Natural dispersal of L. minutus into the experimental plots provided a unique opportunity to examine weevil preference for and effects on C. dif- fusa grown under the different climate change treatments. Elevated CO2 increased both the proportion of seed heads infested by L. minutus and, correspondingly, the amount of seed removed by weevils. Warming had no detectable effect on weevil utilization of plants. Higher weevil densities on elevated CO2 plants reduced, but did not eliminate, the positive effects of CO2 on C. diffusa fitness. Correlations between plant development time and weevil infestation suggest that climate change increased weevil infestation by hastening plant phenology. Phenological mismatches are anticipated with climate change in many plant-insect systems, but in the case of L. minutus and C. diffusa in mixed-grass prairie, a better phenological match may make the biological control agent more effective as CO2 levels rise.

Centaurea stoebe L. ssp. micranthos (Gugler) (spotted knapweed) is an invasive plant that has been the target of classical biological control in North America for more than four decades. The seedhead-feeding weevils Larinus minutus Gyllenhal and Larinus obtusus Gyllenhal (Coleoptera: Curculionidae) are two of the most-widely released C. stoebe control agents, and have more recently been introduced into the eastern US. While there have been many studies focusing on their ability to impact C. stoebe in the western US and Canada, there have been few studies from eastern North America, and basic knowledge of important aspects of their biology is lacking. Here we report on the phenology and dispersal of L. minutus and L. obtusus in Michigan. We regularly sampled two established Larinus spp. populations in southern Michigan in 2012 and 2013, and found that while adult abundance fluctuates during the growing season, they remained at easily detectable levels from mid-June through the end of August. We also used previously established populations of L. minutus and L. obtusus released in 1996 ( n = 1), 2007 ( n = 2), and 2010 ( n = 5) to determine how dispersal of Larinus spp. into the surrounding landscape changes with time since release. Populations of Larinus spp. weevils showed little dispersal for 2 years post-release . However, after initial establishment dispersal rates increased rapidly, resulting in average dispersal rates that increased exponentially with time since release. These findings can inform future biological control release and sampling programs for Larinus spp. in eastern North America.

The syntypes of 41 species of Larinus Dejean described by L. Gyllenhal and C. H. Boheman, housed at the C. J. Schoenherr collection in the Swedish Museum of Natural History, Stockholm and the Museum of Evolution, Uppsala University, are examined. Lectotypes are designated, a nomenclatural review performed, many previous synonyms confirmed and three new synonyms proposed: Larinus planus (Fabricius, 1792) (= Larinus rusticanus Gyllenhal, 1835 syn. nov. ); Larinus carlinae (Olivier, 1807) (= Larinus sulphurifer Boheman, 1843 syn. nov. ); Larinus minutus Gyllenhal, 1835 (= Larinus puncticollis Capiomont, 1874 syn. nov. ). Colour images for 15 lectotypes are presented.