World Journal of Agricultural Research
ISSN (Print): 2333-0643 ISSN (Online): 2333-0678 Website: http://www.sciepub.com/journal/wjar Editor-in-chief: Rener Luciano de Souza Ferraz
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World Journal of Agricultural Research. 2015, 3(4), 119-122
DOI: 10.12691/wjar-3-4-1
Open AccessArticle

Decline in Milkweed (Asclepias syriaca) Populations in Central New Jersey over a One Year Period

Nikhil Gopal1, and Jamie Witsen2

1The Lawrenceville School, Lawrenceville, New Jersey, USA

2Science Department, Montgomery Township Schools, Skillman, New Jersey, USA

Pub. Date: July 05, 2015

Cite this paper:
Nikhil Gopal and Jamie Witsen. Decline in Milkweed (Asclepias syriaca) Populations in Central New Jersey over a One Year Period. World Journal of Agricultural Research. 2015; 3(4):119-122. doi: 10.12691/wjar-3-4-1

Abstract

Milkweed (Asclepias syriaca) is the primary food source of the eastern North American Monarch butterfly (Danaus plexippus), and numbers have been steadily declining. Between 2012 to 2013 we conducted a survey measure to milkweed numbers in Montgomery Township New Jersey. The purpose of this survey was to examine and measure the change in milkweed numbers after a 1 year period. In October 2012, publicly accessible areas of Montgomery Township were surveyed. This same survey was repeated in 2013, and the change in mean number of milkweed plants per plot recorded. Global positioning satellite data were collected using GPS tracker 1.0 for iPhone. All plots from publicly accessible areas were measured except one plot that was intentionally cultivated. Apart from the single intentionally cultivated plot, only 2 plots remained from the original 30 in the 2012 survey (6%). From the original 302 stalks, only 87 remained one year later (a decrease of 71.9 %). A total of 3 new plots were found, indicating new growth. There was a notable decrease in the mean number of milkweed stalks per plot from 2012 (10.4 ± 2.3) to 2013 (4.3 ± 2.4). This decrease was statistically significant at the 5% level (P = 0.03958). Over a one year period, a statistically significant decline in milkweed plants was observed in central New Jersey. More should be done to conserve milkweed populations.

Keywords:
milkweed Asclepias syriaca monarch butterfly Danaus plexippus mitigation conservation

Creative CommonsThis work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]  Brower, L.P., Taylor, O.R., Williams, E.H., Slayback, D.A., Zubieta, R.R., and Ramirez, M.I., “Decline of monarch butterflies overwintering in mexico: Is the migratory phenomenon at risk?,” Insect Conservation and Diversity, 5 (2): 95-100, 2012.
 
[2]  Flockhart, D., Pichancourt, J.B., Norris, D.R., and Martin, T.G., “Unravelling the annual cycle in a migratory animal: Breeding‐season habitat loss drives population declines of monarch butterflies,” Journal of Animal Ecology, 84 (1): 155-165, 2015.
 
[3]  Hartzler, R.G., and Buhler, D.D., “Occurrence of common milkweed (Asclepias syriaca) in cropland and adjacent areas,” Crop Protection, 19 (5): 363-366, 2000.
 
[4]  Pleasants, J.M., and Oberhauser, K.S., “Milkweed loss in agricultural fields because of herbicide use: Effect on the monarch butterfly population,” Insect Conservation and Diversity, 6 (2): 135-144, 2013.
 
[5]  Hartzler, R.G., “Reduction in common milkweed (asclepias syriaca) occurrence in iowa cropland from 1999 to 2009,” Crop Protection, 29 (12): 1542-1544, 2010.
 
[6]  Howard, E., and Davis, A.K., “The fall migration flyways of monarch butterflies in eastern north america revealed by citizen scientists,” Journal of Insect Conservation, 13 (3): 279-286, 2009.
 
[7]  Gopal, N.S., and Witsen, J., "Data from: Field survey results 2012 to 2013 - milkweed populations," Dryad Data Repository.
 
[8]  Persson, T.S., “Management of roadside verges: Vegetation changes and species diversity,” Sveriges lantbruksuniversitet, institutionen foer ekologi och miljoevaard (82), 1995.
 
[9]  Flockhart, D.T., Wassenaar, L.I., Martin, T.G., Hobson, K.A., Wunder, M.B., and Norris, D.R., “Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern north america,” Proceedings of the Royal Society B: Biological Sciences, 280 (1768): 20131087, 2013.
 
[10]  Davis, A.K., “Are migratory monarchs really declining in eastern north america? Examining evidence from two fall census programs,” Insect Conservation and Diversity, 5 (2): 101-105, 2012.
 
[11]  Brower, L.P., Taylor, O.R., and Williams, E.H., “Response to davis: Choosing relevant evidence to assess monarch population trends,” Insect Conservation and Diversity, 5 (4): 327-329, 2012.