Feeding and Oviposition Behavior of Rhinoncomimus

BIOLOGICAL CONTROLÐWEEDS Feeding and Oviposition Behavior of Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) and Its Predicted Effectiveness as a Biological Control Agent for Polygonum perfoliatum L. (Polygonales: Polygonaceae) 1 2 K. COLPETZER, J. HOUGH-GOLDSTEIN, K. R. HARKINS, AND M. T. SMITH Delaware Agricultural Experiment Station, Department ofEntomology and WildlifeEcology, College ofAgriculture and Natural Resources, University ofDelaware, Newark, DE 19716Ð2160 Environ. Entomol. 33(4): 990Ð996 (2004) ABSTRACT Feeding and oviposition on different parts of mile-a-minute weed, Polygonum perfoliatum L. (Polygonales: Polygonaceae), by Rhinoncomimus latipes Korotyaev (Coleoptera: Curcu- lionidae), a potential biological control agent for the weed, were studied in quarantine. An additional experiment was conducted to test the effects of different levels of simulated damage by R. latipes on P. perfoliatum growth, survival, and reproduction. Female weevils consumed more P. perfoliatum overall than males and selectively fed on capitula more than on ocreae or leaves, whereas males fed more on ocreae than on leaves or capitula. More eggs were also laid on capitula than on other plant parts. Female feeding preference is probably because of the high protein content of the capitula, because protein is required for continued egg production, whereas males may maximize their reproductive success by feeding low and close to P. perfoliatum stems to intercept females as they emerge from pupation in the soil and ascend the plants to feed. The feeding and oviposition preferences of female R. latipes for plant capitula suggest that host speciÞcity tests for this species should be conducted with plants that are ßowering. Damage that simulated the effect of R. latipes larval feeding caused plant mortality when it was initiated on small P. perfoliatum plants and reduced biomass and seed production when it was initiated on larger plants. Thus R. latipes could have a substantial impact on P. perfoliatum ifthe weevil is released into the weedÕs introduced range in North America. KEY WORDS Rhinoncomimus latipes, mile-a-minute weed, Polygonum perfoliatum, feeding, simulated herbivory PRACTITIONERS OF CLASSICAL BIOLOGICAL control of Study in quarantine ofthe insectÕs feedingand ovi- weeds are increasingly challenged to show the position behavior on the host plant can help predict its safety of the organisms they propose to import and potential impact on the plant. For example, Eustenopus their predicted effectiveness (DeClerck-Floate and villosus Boheman (Coleoptera: Curculionidae) feed Bourchier 2000, Kluge 2000, McEvoy and Coombs and oviposit on the capitulum (developing seed head) 2000, Louda et al. 2003). Although various methods for ofyellow starthistle ( Centaurea solstitialis L.; Forna- prerelease assessment have been proposed, Blossey sari et al. 1991). This insect is thought to be an effective (1995) concluded that such methods did not effec- control agent because its feeding and oviposition dis- tively allow for selection of the most successful agents torts C. solstitialis buds and reduces seed production before release, even for insect species that had been (Fornasari et al. 1991, Fornasari and Sobhian 1993, extensively studied in their European home range Connett et al. 2001). Study ofthe herbivoreÕs pre- before release in North America. For alien plants that ferred feeding and oviposition site can also help with originate in Asia, the lack ofeasily accessible literature the design ofan appropriate postrelease monitoring and research infrastructure has often hampered such strategy by suggesting where the insect is most likely extensive Þeld studies in the native range. Neverthe- to be found and may also help ensure the proper less, several approaches may help assess potential ef- evaluation ofhost speciÞcity. For example, ifan agent fectiveness of new agents before release in a new area. only oviposits on the ßowers ofits host or only oviposits when its host is ßowering, host speciÞcity tests should be conducted with plants that are ßowering. 1 E-mail: [email protected]. 2 United States Department ofAgricultureÐAgricultural Research Both egg maturation and oviposition behavior can Service BeneÞcial Insect Introduction Research Unit, Newark, DE vary substantially depending on host availability and 19716. quality (Papaj 2000). 0046-225X/04/0990Ð0996$04.00/0 ᭧ 2004 Entomological Society ofAmerica August 2004 COLPETZER ET AL.: R. latipes ON P. perfoliatum 991 Experimental simulation ofthe agentÕs observed plete development, exit the stem, and drop to the soil mode ofdamage to the host plant is another possible for pupation. Damage to the plant occurs primarily approach to assessing potential effectiveness. For ex- from larval feeding, which kills the stem from the exit ample, McEvoy et al. (1991) used simulated herbivory hole to the stem terminal (Price et al. 2003). In China, as part ofan assessment ofthe impact ofcinnabar moth adult weevils overwinter in litter and emerge in the (Tyria jacobaeae L., Lepidoptera: Arctiidae) feeding spring when P. perfoliatum is 30Ð50 cm tall. The weevil on tansy ragwort (Senecio jacobeae L.). Simulated is thought to be univoltine in northern China, but may damage can suggest the plantÕs sensitivity to the type have multiple generations further south (D. Jianqing, ofdamage inßicted by the proposed agent, although personal communication). the effects of mechanical damage may differ from actual herbivory (Baldwin 1990), and damage to in- Materials and Methods dividual plants may not translate directly to impacts on plant populations. TifÞn and Inouye (2000) compared Rhinoncomimus latipes Feeding and Oviposition estimates ofplant damage fromnatural versus artiÞcial Behavior. Rhinoncomimus latipes originating from or manipulated herbivory and concluded that esti- adults collected in Changsha, Hunan province of mates derived from simulated herbivory are likely to China in 2000 and 2001 were reared on P. perfoliatum be unbiased, but less precise, than those from natural in a quarantine room kept at 22 Ϯ 0.5ЊC at the USDA- herbivory. ARS BeneÞcial Insects Introduction Research Unit in In this study, feeding and oviposition on different Newark, DE, using the methods ofPrice et al. (2003). parts ofmile-a-minute weed, Polygonum perfoliatum Voucher specimens of R. latipes have been deposited L. (Polygonales: Polygonaceae), by Rhinoncomimus in the University ofDelaware Department ofEnto- latipes Korotyaev (Coleoptera: Curculionidae) were mology and Wildlife Ecology Insect Reference Col- studied in quarantine. In addition, an experiment was lection. conducted to test the effect of different levels of sim- Polygonum perfoliatum plants were grown in a ulated damage by R. latipes on P. perfoliatum growth, greenhouse from seeds collected locally and germi- survival, and reproduction. nated using the methods ofColpetzer and Hough- Polygonum perfoliatum is an annual vine indigenous Goldstein (2004). Plants were supplied with drip ir- to temperate regions ofBhutan, China, India, Indo- rigation and supplemental light that provided a 16-h nesia, Japan, Korea, Nepal, the Philippines, Russia, and photophase and a minimum photosynthetic photon Vietnam (Wu and Raven 2003). It was introduced into ßux of200 ␮mol/m/s. They were fertilized every other a nursery in Stewartstown, PA, during the 1930s (Moul week with 250 ml ofa 0.4% solution ofMiracle-Gro 1948, Riefner 1982), and has since spread to Delaware, Professional (21% N; 5% P; 20% K). the District ofColumbia, Maryland, New Jersey, New Ten newly emerged male and 10 newly emerged York, Ohio, Virginia, and West Virginia (Oliver 1996), female R. latipes adults were placed individually in and more recently, Connecticut (Lamont and Fitzger- plastic cylindrical cages (15 cm diameter by 20 cm ald 2001). It has been listed as a noxious weed in high) with removable screen covers. The weevils were several states because it forms dense, prickly thickets sexed by assessing the shape ofthe metasternum, that displace native vegetation, interfere with forest which is more convex in the female than in the male regeneration, and reduce the recreational value of (Price et al. 2003). Once oviposition began, females natural areas (Mountain 1989, McCormick and were marked with white-out (Sailor Corporation of Hartwig 1995, Oliver 1996). America, Fayetteville, GA) on their elytra to facilitate The USDA Forest Service initiated a classical bio- sorting following mating. logical control program for P. perfoliatum in 1996. Each container was supplied with a freshly cut During 6 yr ofÞeld surveys in China, over 100 insect P. perfoliatum stem in a 125-ml Erlenmeyer ßask Þlled species were collected from P. perfoliatum (Ding et al. with water and stopped with cotton. All stems were 20 2004). One ofthe most promising, both in terms of cm long, with a single capitulum (Fig. 1), and were observed impact on the plant in China and host- taken from 1.5- to 2-mo-old plants. Stems were re- speciÞcity (Price et al. 2003, Colpetzer et al. 2004), placed every3dfor63d.When plant material was was Rhinoncomimus latipes Korotyaev. This weevil changed, all 20 R. latipes were placed in a 9-cm petri was initially misidentiÞed as Homorosoma chinensis dish and allowed to mate for Ϸ2h. (Wagner) (synonym: Homorosoma chinense Wagner). Each time plant material was changed, feeding dam- Specimens were later sent to B. A. Korotyaev ofthe age was measured on ocreae (saucer-shaped leafy Zoological Institute ofthe

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