Monarch-parasite interactions in managed and roadside prairies

Published source details Mueller E.K. & Baum K.A. (2014) Monarch-parasite interactions in managed and roadside prairies. Journal of Insect Conservation, 18, 847-853.
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This study is summarised as evidence for the following.

	Action	Category
	Restore or maintain species-rich grassland along road/railway verges Action Link

Restore or maintain species-rich grassland along road/railway verges

A replicated, site comparison study in 2012 along three highways and in three prairies in Oklahoma, USA (Mueller & Baum 2014) found that monarch Danaus plexippus caterpillars living on managed road verges had a similar number of parasites to caterpillars on lightly managed prairies. There was no significant difference in the rate of infection with parasitic flies Lespesia archippivora or protists Ophryocystis elektroscirrha between caterpillars from road verges (L. archippivora: 28%; O. elektroscirrha: 28% infected) and prairies (L. archippivora: 42%; O. elektroscirrha: 24% infected). A total of 47 caterpillars were collected from road verges, and 76 from prairies. Between April and October 2012, the verges of three highways were mown once or twice and sprayed with herbicide, and three managed prairies (0.07–0.19 km²) were mown once or not at all. From April–May and September–October 2012, every milkweed Asclepias viridis plant in three 1,000 × 40 m survey areas (2 km apart) along each highway, and on the whole area of each prairie, was inspected 2–4 times/week and all large monarch caterpillars were collected and reared in the lab. The number of L. archippivora parasites which emerged from caterpillars or pupae were counted, and adult monarchs were checked for the presence of O. elektroscirrha spores.

(Summarised by: Andrew Bladon)