Insect Diversity on Mount Mansfield
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Introduction pitfall traps located around each plot at 60° This report concludes the fifth consecutive intervals. In previous years a single light year of insect surveys on Mount Mansfield. trap was located in the center plot, but in The purpose of this program is to develop 1995 two additional light traps were information on taxonomic diversity and included and located outside the permanent species abundance of selected insect groups plot no less than 30 m apart. At Proctor in the forest ecosystem at different Maple Research Center and Underhil1 State elevations. This information will contribute Park traps two and three correspond to the a taxonomic foundation for future work on single trap used in previous years. Three the ecological relationships between traps were also established at the 715 m site. invertebrate biodiversity and forest management. The 1995 Lepidoptera survey was limited to Noctuidae, Geometridae, The first three years of the insect Notodontidae, Arctiidae, Satumiidae, survey included Hymenoptera and Diptera Lasiocampidae, Drepanidae, Sesiidae, and from canopy malaise traps, ground beetles Limacodidae. These groups were selected (Carabidae) from pitfall traps and because it was possible to provide accurate Lepidoptera from light traps. The canopy identifications for most specimens within the study was. discontinued after the first three time constraints of the study, with the years, and the data from this and ground exception of Limacodidae which turned out surveys are being analyzed for statistical to be impractical because of similarities comparisons of diversity variation among among some species. the three study sites. Results Comparisons are presented in this (A) Pest species report for general between-site diversity , A few specimens of the gypsy moth individual pest species, and examples of (Lymantria dispar) were recorded for the elevation differences for individual species. first time in this survey (Table 1). The The potential ecological significance of these survey area is not prime gypsy moth habitat, patterns for forest management is briefly so its low level of occurrence is anticipated. discussed. A considerable increase in numbers Methods of forest tent caterpillar Malacosoma disstria In 1995 the Lepidoptera and ground beetle and eastern tent caterpillar M. americanwn, surveys continued at established sampling were observed in 1994, but numbers plots in a sugar maple forest (proctor Maple collected for both species in 1995 were no Research Center, 400 m), and a mixed higher than for any of the first three years hardwood forest (Underhill State Park, 640 of collecting (Fig. 1). The highest numbers m). A new Lepidoptera sampling site was of both species continued to be collected at established in a birch-mixed-hardwood forest PMRC. Neither species was collected from at 715 m in Underhill State Park. the new USP715, and no specimens of the eastern tent caterpillar were collected from The established survey sites comprise USP640. five permanent 20 m diameter plots with six 156 Figure I. Annual total number of adults of (a) forest tent caterpillar , Malacosoma disstria and (b ) eastern tent caterpillar , M. americanum, collected over a five-year period on Mount Mansfield at Proctor Maple Research Center and Underhill State Park (640 m). (a) /1 100( 71 -0 Q) 80 !3 0! o (J 60 (b) cn .c "71 O 40 E "iU 20 ;§ 0!/ / / / / " 1991 1992 1993 1994 1995 Collection year Specimens of saddled prominent, those of saddled prominents at all sites, with Heterocampa guttivita (Notodontidae) were emergence of saddled prominent begining noted during the 1990-1994 survey, but earlier in the season (Fig. 2). The results were not counted because they could not be indicate that saddled prominent abundanceis easily distinguished from the wavy-lined not cause for concern on Mt Mansfield. If prominent, H. biundata. This problem was larval feeding by wavy-lined prominents is overcome in 1995 by removing scales from also destructive to host trees, its greater the terminal portion of the ventral abdominal abundance may suggest that its population surface and comparing the size of sensory trends should also be monitored on a regular pits for males in the two species (relatively basis. The last major outbreak of saddled few females were collected). Numbers of prominent in Vermont occurred in the early wavy-lined prominents greatly exceeded 1980's (parker et al. 1989). 157 Figure 2. Seasonal abundance of saddled prominent, Heterocampa guttivita, and wavy-lined prominent, H. biundata, at (a) Underhi1l State Park (715m), (b) Underhill State Park (640 m), and Proctor Maple Research Center (400 m) in 1995. 801 In 0. m = 601 Q) Q) .c ~ m 40 (a) ,0 E :J c: c: 20 m Q) ~ ~ ~0 .('0 ~ ~~~ ;s.~ ~-:>' ~-:>' ~v ~ tJ,tJ, ~ bo~ ~ " 70, (b) (c) Orange-humped mapleworm included in earlier years of the survey. For (Symmerista leucitys) is a minor pest in most the 1995 samples species were identified by parts of its range although it is also examination of male genitalia following responsible for local severe defoliations descriptions provided by Franclemont (Allen 1979, Houston et al. 1990) including (1946). The orange-humped maple-worm Vermont (Teillon et al. 1978). External was more common than the white-headed features do not separate the different species maple-worm (S. albifrons) (Fig. 3), but both of Symmerista so systematic counts were not were present in relatively low numbers. 158 Figure 3. Abundance of adults of orange-humped mapleworm, Symmerista leucitys, and white- headed mapleworm (S. albifrons) on Mt Mansfield, 1995. c: "' Q) ~ ~ ~""' .~~ 0~ v<'~ Collection date (B) Elevation Patterns higher elevations (Fig. 4), but was similar to A verage numbers of moth individuals and USP640, both of which were lower than species did not show a large amount of USP7l5. variation between sites. PMRC supported slightly higher numbers of species than the Figure 4. Mean numbers of (a) species, and (b) individual moths collected at each site on Mt. Mansfield in 1995. 601 0. ~50 (a) ~ 40 E - ~ 30 c ~ 20 ,.::.:;' 10 0 "" ~"\ "" ,# ,...0 ,,'.' Site (b) ~ ~ "" ~tf' ~~'0"" ~o' be"" q'O .;)" Site 159 ~ Large numbers of the lesser maple 5). The opposite pattern is found for the spanworm (ltame pustularia, Geometridae) Welsh wave (Venusia cambrica, were noticed at all sites, including around Geometridae) which is recorded from a lights on buildings at PMRC. As the range of trees, including alders, birch, common name implies, the lesser maple mountain ash, and willow. The higher spanworm is a maple feeder of several numbers present at the higher elevation sites species and it is also sometimes a pest (Fig. 6) may reflect these host-plant (Coven 1984). It is no surprise to see its associations, particularly for USP715 where highest abundance at PMRC, with less than birch and ash are common. half as many at the higher elevations (Fig. Figure s. Mean abundance of lesser maple spanworm, ltame pustularia (Geometridae), on Mt Mansfield in 1995. Proctor (400 m) Underhill (640 m) Underhill (715 m) Figure 6. Mean abundance of welsh wave, Venusia cambrica (Geometridae), on Mt Mansfield in 1995. Proctor (400 m) Underhill (640 m) Underhill (715 m) 160 project is to relate the taxonomic occur north of the Mexican border biodiversity of Mt Mansfield Lepidoptera to (Lepidoptera, Notodontidae). The its ecological and management significance. Canadian Entomologist 78:97-103. The first step, already initiated, is the Houston, D. R. , D. C. Allen, and D. development of a general host-plant list for Lachance. 1990. Sugarbush management: representative groups of Mt Mansfield a guide to maintaining tree health. Lepidoptera. This project could also be Northeastern Forest Experiment Station complemented by a targeted program to rear General Technical Report NE-129. Lepidoptera larvae from trees, shrubs and Parker, B. L., K. E. McGrath, S. Moulton, herbs as host-plant relationships may vary and H. B. Teillon. 1989. History of the with geography and elevation. major forest insect pests in Vermont. A joint VT Agricultural Experiment Station Host-plant documentation will allow and State of VT publication. RR 57. general predictions about the ecological and University of Vermont, Burlington. potential forest management significance of Rockburne, E. W. , and J. D. Lafontaine. the Lepidoptera biodiversity structure on Mt 1976. The cutworm moths of Ontario and Mansfield. It will be important to identify Quebec. Canada Department of and understand the range of host-plant Agriculture Publication 1593. relationships present on the Mountain and Teillon, H. B., R. S. Kelly, and E. E. how these may vary over elevation and Keenan. 1978. Forest and insect disease between habitats. Questions concerning the conditions, 1977. Department of Forests, relative significance of rare and common Parks, and Recreation. Montpelier , moths in relation to the distribution and Vermont. abundance of trees and other plants may be assessed. These relationships, once identified, will provide an ecological context against which testable predictions may be made about the ecological impact of different forest management practices on insect biodiversity in mixed northern hardwoods characteristic of Mt Mansfield. References Allen, D. C. 1979. Observations on biology and natural control of the orangehumped mapleworm, Symmerista leucitys (Lepidoptera: Notodontidae), in New York. The Canadian Entomologist 111 : 703-708. Covell, C. V. Ir. 1984. Eastern Moths. Houghton Mifflein Company, Boston. Franclemont, I. G. 1946.