Feeding Preference of Three Lady Beetle Predators of the Hemlock Woolly Adelgid (Homoptera: Adelgidae) Author(S): Elizabeth E
Total Page:16
File Type:pdf, Size:1020Kb
Feeding Preference of Three Lady Beetle Predators of the Hemlock Woolly Adelgid (Homoptera: Adelgidae) Author(s): Elizabeth E. Butin, Nathan P. Havill, Joseph S. Elkinton, and Michael E. Montgomery Source: Journal of Economic Entomology, 97(5):1635-1641. 2004. Published By: Entomological Society of America DOI: http://dx.doi.org/10.1603/0022-0493-97.5.1635 URL: http://www.bioone.org/doi/full/10.1603/0022-0493-97.5.1635 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. FOREST ENTOMOLOGY Feeding Preference of Three Lady Beetle Predators of the Hemlock Woolly Adelgid (Homoptera: Adelgidae) ELIZABETH E. BUTIN,1 NATHAN P. HAVILL,2 JOSEPH S. ELKINTON,1 2 AND MICHAEL E. MONTGOMERY J. Econ. Entomol. 97(5): 1635Ð1641 (2004) ABSTRACT In a laboratory study, we tested the feeding preferences of three coccinellid predators of hemlock woolly adelgid, Adelges tsugae Annand, an introduced pest of hemlock in the eastern United States. The species tested were Sasajiscymnus tsugae Sasaji & McClure (formerly Pseudoscym- nus tsugae) from Japan, Scymnus ningshanensis Yu & Yao from China, and Harmonia axyridis (Pallas), a generalist species introduced from Asia that is currently widespread in eastern hemlock, Tsuga canadensis Carriere, forests. We measured the feeding preference of each beetle species when given the choice of A. tsugae and either 1) Pineus strobi (Hartig) on Pinus strobus L.; 2) Adelges laricis Vallot on Larix decidua Mill.; 3) Adelges cooleyi (Gillette) on Pseudotsuga menziesii (Mirb.) Franco; or 3) Paraprociphilus tessellatus (Fitch) on Alnus serrulata (Ait.) Willd. We evaluated beetle preference for adults, nymphs, and eggs of each prey species. Generally, when adult or nymphal prey stages were compared, S. tsugae preferred A. tsugae adults to P. strobi, A. cooleyi, A. laricis, and P. tessellatus. S. ningshanensis showed less preference between adelgid species, but it did not prefer P. tessellatus nymphs. When preferences for adelgid eggs were assayed, S. tsugae and S. ningshanensis showed no preference between A. tsugae and A. cooleyi or P. strobi, but S. tsugae did prefer A. tsugae to A. laricis. Larvae of S. tsugae were unable to survive on P. tessellatus nymphs. H. axyridis adults readily consumed both A. tsugae and P. tessellatus, but H. axyridis larvae did not complete their life cycle on A. tsugae. Our host range tests suggest that S. ningshanensis and S. tsugae may feed on several species of Adelgidae and that A. tsugae is often preferred. KEY WORDS hemlock woolly adelgid, woolly alder aphid, preference testing, Pseudoscymnus tsugae SOME INTRODUCED BIOLOGICAL control agents have been canadensis Carriere, and on Carolina hemlock, Tsuga shown in retrospect to exert negative impacts on non- caroliniana Englemann (Orwig and Foster 1998). target species (Simberloff and Stiling 1996, Follett et Hemlock species in western North America are resis- al. 2000, Strong and Pemberton 2000). Prerelease host tant to A. tsugae, but hemlock species in eastern North preference testing can help prevent this by indicating America can be severely injured or killed (Orwig and the breadth of a biological control agentÕs host range. Foster 1998). In the past, host range evaluations examined only one Chemical control of the hemlock woolly adelgid is potential candidate for introduction in isolation from not feasible in forested areas, and native natural en- other candidates, even though a guild of natural en- emies have not suppressed A. tsugae populations in emies may control the pest in its native habitat (Van North America (Montgomery and Lyon 1996, Wallace Driesche and Bellows 1996). We used choice tests and and Hain 2000). The most promising control option for developmental assays to examine the preference of A. tsugae is classical biological control, or the impor- three lady beetle species for the hemlock woolly ad- tation, release, and establishment of non-native nat- elgid, Adelges tsugae Annand, versus selected nontar- ural enemies for control of exotic pests (Cheah and get insect species. McClure 1996). The hemlock woolly adelgid is found in Asia and Several predatory beetles have been evaluated for western North America (Blackman and Eastop 1994). biological control of A. tsugae. In China and Japan, It was Þrst discovered in eastern North America in coccinellids are abundant and widespread natural en- Virginia in 1951 (Anonymous 1968). Hemlock woolly emies of A. tsugae (Sasaji and McClure 1997, Wang et adelgid now occurs in the Mid-Atlantic states and al. 1998). Sasajiscymnus tsugae (Sasaji & McClure) was southern New England on eastern hemlock, Tsuga imported from Japan in 1992, released throughout Connecticut in 1995, and is now established in local- 1 Department of Entomology, 102 Fernald Hall, 270 Stockbridge ized populations throughout Connecticut (McClure Rd., University of Massachusetts, Amherst, MA 01003. 2 USDAÐForest Service Northeastern Research Station, Northeast- et al. 2000). Scymnus ningshanensis Yu & Yao was ern Center for Forest Health Research, 51 Mill Pond Rd., Hamden, CT imported from Yunnan province of China in 1998 and 06514. is a candidate for release (Yu et al. 2000). The third 0022-0493/04/1635Ð1641$04.00/0 ᭧ 2004 Entomological Society of America 1636 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 97, no. 5 predator evaluated, Harmonia axyridis (Pallas), a na- and S. ningshanensis adults were obtained from the tive of Asia, was released for biological control of USDAÐForest Service Insect Rearing Facility (Ham- arboreal aphids (Hagen et al. 1999) and has been den, CT). H. axyridis were Þeld collected as pupae on shown to feed on A. tsugae (Wallace and Hain 2000). the University of Massachusetts, Amherst campus, and Environmental organizations, public ofÞcials, and eclosed 1 wk before the experiment. All predators land managers are concerned about potential impacts were maintained at 18ЊC and a photoperiod of of coccinellids such as S. tsugae, S. ningshanensis, and 16:8 (L:D) h on locally collected hemlock infested H. axyridis on nontarget species, especially on the with ovipositing hemlock woolly adelgid. Lady beetle woolly alder aphid, Paraprociphilus tessellatus (Fitch). eggs also were obtained from these stocks, except for Woolly alder aphid is the primary prey of the butterßy H. axyridis that were Þeld collected. Feniseca tarquinius F. This butterßy is the only pre- daceous lepidopteran in the continental United States, and its larvae depend upon woolly alder aphid and Choice Tests several other woolly species of Homoptera to com- plete their life cycles (Scott 1997). The test arena consisted of a 9-cm petri dish with There is limited host preference information for the moistened Þlter paper on the bottom. Branch tips of three lady beetle species considered here. The host eastern hemlock infested with A. tsugae and branch ranges of S. tsugae and S. ningshanensis have not been tips of the host plant with the alternate prey item were well documented, nor has the preference of H. axyri- placed on opposite sides of the dish. Each branch was dis for A. tsugae over other prey. Although considered 2 cm in length. We chose pieces of hemlock and a primary predator of A. tsugae in Japan, S. tsugae also alternate host plants that were similar in size, so that was collected on grasses and shrubs at marshy sites in the amount of foliage on each plant did not inßuence Japan (Sasaji and McClure 1997). Preliminary labo- beetle preferences. ratory tests in New England showed that S. tsugae In 2001 and 2003, adult S. tsugae and S. ningshanensis fed on Adelges cooleyi (Gillette) and Pineus strobi used in the choice tests had eclosed 4Ð6 wk before (Hartig) (Cheah and McClure 1996), and it has been testing, and H. axyridis had eclosed 1 wk before test- reared on Adelges piceae (Ratzeburg) (C. Cheah, per- ing. All beetle species were starved for 24 h, and one sonal communication). The host range of S. nings- beetle was placed in the center of each dish. The initial hanensis has not been reported, but the beetle has number of prey items was recorded for each presented been collected only from hemlock and reared on re- prey type. We allowed each beetle to feed for 24 h at productive A. tsugae (Wang et al. 2000). S. ningshanen- 18ЊC and a photoperiod of 16:8 (L:D) h. After 24 h, we sis has been shown in the laboratory to respond nu- removed the beetles and recorded the number of prey merically to increasing densities of A. tsugae and in items remaining. Trials were conducted for each of the caged Þeld studies to reduce hemlock woolly adelgid three lady beetles species for all choice combinations, populations (Butin et al. 2003). H. axyridis is a well- except where indicated. established, generalist predator abundant throughout In 2001, in addition to the feeding data, we observed eastern North America (Hagen et al. 1999) and is the dishes for the Þrst 15 min after a beetle was added considered by some to be a nuisance because it in- and recorded the time spent on each host plant (time vades homes (Wheeler 1995). H. axyridis feeds vora- spent on the dish was excluded). After the 24-h feed- ciously on aphids (Hagen et al.