Invasion of the Non-Natives!
There has been a high change in vegetation the past few years, due to altered management and invasive plants have and are continuing to alter the quality of the remaining habitats of these Mission Blue Butterflies (The Xerces Society). Also invasive and non-native plants are killing their main food source such as buckwhite and Lupine (Weinberg, 2011). Due to invasive ability to become more abundant while outcompeting or becoming more abundant than the larval food plant and nectar plants. Non-native species keep growing because of the higher levels of nitrogen in the soil found in urban environments.
Lupin Killers On the Loose
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The Lupin Flower, whose survival depends on the pollination from the Mission Blue butterflies (image from Nelson, 2014)
Non-natives introduced from high amounts of nitrogen released by the massive amounts of cars in San Francisco (image from Transportation/Traffic, 2016)
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An easy food source for wasp and other dominant insects as well as rodents (U.S. Fish & Wildlife Service. 2016). Most of the Mission Blue Butterflies predators are pest insects such as the parasitoid wasp. This wasp hatches their eggs laid inside the caterpillars body. The tiny wasp larvae then kills the caterpillar as they eat their way out (Kobernus, 2010).These pest tend to be pray on Mission Blue butterfly because they are an easy target because Mission Blue Butterflies are not predators themselves. The Mission Blue Butterflies only feed on nectar from flowers (U.S. Fish & Wildlife Service. 2016) and don't have defence mechanisms to ward of predators.
Mission Blues an Become an Easy Target for Predators!
The non natives can handle high amounts of nitrogen, while natives can’t, and therefore butterflies have no plant species to depend on. This high amount of nitrogen is due to the burning of fossil fuels, which occurs because of the high amounts of automobile traffic in San Francisco. In order to decrease the amount of non-natives in the area herbicides are now being used. (Formidable odds against reintroduction of Mission Blue butterfly, 2012) In the past the use of pesticides on plants such as the lupine which are often considered weeds by garden growers for its fast growing rate when put in the right soil conditions, gave a 24-36% reduction in the number of caterpillars making it to the pupa stage (Save Mount Sutro Forest,2013), causing the decline in Mission Blue butterflies (Save Mount Sutro Forest,2013).