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					             Scymnus (Pullus) coniferarum Crotch 1874 (Coleoptera: Coccinellidae)
                                     An Adelgid Predator Native to the Western United States
                                                         Michael E. Mongtomery1, Richard McDonald2, Laura Schwartzberg3
                                                 1US    Forest Service, Northern Research Station, Hamden, CT; 2Symbiont, Sugar Grove, NC; 3South Salem, NY


                                                                                                                                                                                             Occurrence
                                                                                                                   Scymnus coniferarum was previously collected from several western U.S. states and from
                                                                                                                   British Columbia (Fig. 4). The majority of collections were in California.



                                                                                                                                                                                                                   Figure 4. Collection records of Scymnus
                                                                                                                                                                                                                   (P.) coniferarum based on museum
                                                                                                                                                                                                                   specimens; shaded = general area of
                                                                                                                                                                                                                   many collections with dots showing
                                                                                                                                                                                                                   peripheral localities (from Gordon 1985);
                                                                                                                                                                                                                   red rectangle is area of recent collections
                                                                                                                                                                                                                   in the Seattle area by the authors.




                                                                                                                    Since it has been found in northern Idaho and southern Arizona, its climate range seems to
                                                                                                                    be broad.
          Figure 1. Scymnus (Pullus) coniferarum. Photo by Nathan Havill.
                                                                                                                    The type specimens collected in 1874 were from pine and an unpublished thesis by
                                                                                                                    Whitehead stated that large numbers of S. coniferarum were collected from lodgepole pine
                                                                                                                    and Monterey pine infested with woolly adelgid.
                                           Summary
                                                                                                                    The extensive survey for predators on hemlock by Kohler (2007) found only a single
 The conifer lady beetle, Scymnus coniferarum Crotch, is widely                                                     specimen of S. coniferarum. We collected S. coniferarum from western hemlock, Tsuga
 distributed in the western United States. We have collected more than                                              heterophylla infested with Adelges tsugae (Table 1). We also sampled fir and western white
 200 specimens in the Seattle, Washington, metropolitan region from                                                 pine infested with S. coniferarum, but did not recover this lady beetle. Its distribution among
 adelgid infested hemlock. We have established a laboratory colony and                                              trees is patchy, with trees in locations exposed to direct sunlight favored.
 reared it through a complete generation on the hemlock woolly adelgid.
 Its biology and host range are being evaluated to assess its potential
 for biological control of Adelges tsugae in the eastern United States.
                                                                                                                         Table 1. Relative number of Laricobius nigrinus (Ln) and Scymnus coniferarum (Scw) collected from
                                                                                                                         western hemlock in the Seattle, Washington, metropolitan area.
                                                                                                                                         Date                                                   Site                                      Ln              Scw
                                           Appearance
                                                                                                                                     26-Feb-08                   Ft. Lawton                                                                    131               40
   The lady beetle genus Scymnus has more than one hundred species
   in the United States, with the majority in the subgenus Pullus. These                                                              04-Apr-08                  Chittenden Locks                                                                73              36
   are small in size, usually less than 3.0 mm with pubescence on the
   dorsal surface, antennae 11-segmented, and an incomplete postcoxal                                                                10-May-08                   Washington Park Arboretum                                                                       10
   line. Scymnus (Pullus) coniferarum Crotch (Fig. 1) can be
   distinguished from the other native lady beetles in the subgenus                                                                  11-May-08                   Chittenden Locks                                                                                24
   Pullus by its more elongate shape (length 1.75 mm, width 1.15 mm)
   and distinctive coloration consisting of black pronotum with antero-                                                              11-May-08                   Washington Park Arboretum                                                                        9
   lateral angles yellowish brown and a yellowish brown elytron with
   base, triangular area at scutellum and suture piceous (Gordon 1976).                                                               16-Oct-08                  Discovery Park                                                                  57              12

                                                                                                                                      19-Oct-08                  Washington Park Arboretum                                                     188                2
                                                    Its coloration closely resembles
                                                    Scymnus (Pullus) suturalis                                                        21-Oct-08                  Firecrest                                                                     150                1
                                                    Thunberg (Fig. 2), an introduced
                                                    species established in the eastern                                                22-Oct-08                  Salt Hood, Seattle                                                            320                1
                                                    U.S.), but the latter is less elongate
                                                    and the punctures on the elytron are                                              23-Oct-08                  Marymoor, Bellevue                                                            214                1
                                                    coarser, separated by slightly less
                                                    than the diameter of a puncture                                                  23 –Oct-08                  Ft. Lawton                                                                    100                8
                                                    (Gordon 1985).
                                                                                                                                      23-Oct-08                  Discovery Park                                                                  45               1
  Figure 2. Scymnus (Pullus) suturalis.
  Photo by I. Altman                                                                                                                  26-Oct-08                  Seig Hall, University of Washington                                            115               2

 The shape of the male genitalia is a primary character that                                                                         15-Nov-08                   Ft. Lawton                                                                      30              42
 taxonomists use to identify Scymnus species and the sipho
 can be used to readily distinguish these two species (Fig. 3).                                                                          Total                                                                                                 1423              173




                                                                                                                                                                                    Lab Rearing
                                                                                                                   Scymnus coniferarum has been relatively easy to rear in the laboratory. At temperatures from 12
                                                                                                                   to 20° C, it reproduced when A. tsugae on T. canadensis was its food source. The immatures
                                                                                                                   completed development in 34 days on A. tsugae. Adults ate a mean of 8.6 eggs, 2.8 nymphs,
                                                                                                                   and 1.0 adults/24 hr. Oviposition by the females was very sensitive to food quality; those
                                                                                                                   receiving only A. tsugae nymphs did not oviposit. Currently, an F-2 generation is being
                                                                                                                   produced in the laboratory. Its biology, feeding on both pine and hemlock adelgids, are similar
              Figure 3. Male genitalia of Scymnus (Pullus) coniferarum and S. (P.)
                                                                                                                   to S. suturalis (Montgomery and Lyon 1996).
              suturalis; (a, b = genitalia; c, d = sipho).

                                                                                                                            References Cited
Crotch, GR. 1873. Revision of the Coccinellidae of the United States. Trans. Am. Entomol. Soc. (Phila.) 4: 363-382.
Gordon, RD. 1976. The Scymnini (Coleoptera: Coccinellidae) of the United States and Canada: Key to genera and revision of Scymnus, Nephus, and Diomus. Bull. Buffalo Soc. Nat. Sci. 28: 1-71.
Gordon, RD. 1985. The Coccinellidae (Coleoptera) of America North of Mexico. J. New York Entomol. Soc. 93: 1-912.
Kohler, GR. 2007. Predators associated with hemlock woolly adelgid (Hemiptera: Adelgidae) infested western hemlock in the Pacific Northwest; 121 pages, Dept. Forest Sci., Oregon State Unviersity
Montgomery, ME, Lyon, SM. 1996. Natural enemies of adelgids in North America: Their prospect for biological control of Adelges tsugae (Homoptera: Adelgidae), pp. 89-102. In SM Salom, TC Tigner, RC Reardon (eds.). Proceedings of the
  First Hemlock Woolly Adelgid Review, Charlottesville, VA, Oct. 12, 1995. USDA Forest Service, FHTET,Morgantown, WV.

				
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