Herbicide Effects on Host Plants of Karner Blue Butterfly and on Butterfly Development from Egg to Adult

Two studies examined the compatibility between herbicide release of red or jack pine plantations in Wisconsin and the maintenance of Karner blue butterfly (Lycaeides melissa samuelis), a federally listed endangered species. Wisconsin has some of the few remaining viable metapopulations of Karner blue butterfly, hereafter abbreviated as KBB. The habitats favored by KBB are also the sites well suited for the red pine (Pinus resinosa)and jack pine (Pinus banksiana) plantations that supply the socioeconomically important forest industries. The survival and rapid growth of the pine seedling frequently requires removing vegetative vegetation with herbicides that incidentally also may affect the food sources for KBB. In order to document the effects of herbicides, we examined how herbicides altered wild lupine (Lupinus perennis), the sole food source for KBB larvae, and 14 major nectaring plants, that supply the nectar on which KBB adults depend. Simulated operational levels of Accord ® (glyphosate), Accord+Oust ® (sulfometuron methyl), and Accord+Garlon4 ® (triclopyr), all with the adjuvant EntryII ® , were sprayed on 350m 2 plots located in seedling red or jack pine stands. Before and for up to three years after spraying, we observed the percent-cover and number of flowering stems of the selected species. A total of 891 measurement-plots were involved. The results clearly documented that lupine cover and flowering were not inhibited by herbicide treatments and may have been modestly stimulated. In contrast, the percent-cover and flowering of most, but not all, nectaring plants, were reduced the first year after herbicide application. Many species began to regain cover by the second year after spraying. Most, however, had not returned to prespray levels when observations ended two or three years after spraying. The numbers of flowering stems recovered more rapidly and completely than percent-cover. First year responses to herbicides varied among species from total mortality to significant increases. Among herbicides, Accord+Oust had the most negative effects on percent-cover. Late August applications of herbicides had more negative effects on nectaring plants than did early September applications. At this time, the effects of herbicides on KBB food sources cannot be related to changes in KBB populations. The second study examined the effects on the development of KBB when these same herbicide formulations as well as Garlon4 were sprayed directly on the eggs of Karner blue butterfly. Operational concentrations of Garlon4, Accord or Accord+Oust, all with EntryII, did not affect egg development, but egg hatching was significantly lowered …