FALL AND WINTER BREEDING MONARCHS IN TEXAS
Submission Type: Poster
DAVID D BERMAN , Oklahoma State University, Stillwater, OK
KRISTEN A BAUM, Associate Professor Oklahoma State University, Stillwater, OK
Monarch butterflies (Danaus plexippus plexippus) migrate from overwintering grounds in central Mexico
to breeding grounds in the Upper Midwest and southern Canada. Texas is critical to the migratory
population because it provides nectar for spring and fall migrants and milkweed for 1st and 5th generation
monarch caterpillars. Additionally, Texas has a non-migratory, winter breeding monarch population along
the Gulf Coast during milder winters. This population of non-migratory monarchs share the same habititat
with the migratory population when they present in Texas. Therefore, understanding the local habitat
preferences and survival rates of monarchs in Texas is important for conservation planning for the overall
monarch population. We are evaluating host plant associations and parasitism rates for 5th generation and
winter breeding monarchs in Texas. The parasites of interest are Ophryocystis elektroscirrha (OE) and
tachinid flies. OE is an obligate spore forming protist found in varying levels in monarch and queen
butterfly populations worldwide. Infection rates tend to increase over the breeding season and are higher
in non-migratory monarch populations. Tachinid flies are parasitoids that develop inside their host,
typically killing the host when they emerge sometime between the 5th instar to chrysalis stage. Tachinid
fly parasitism can be locally high and is an important source of monarch mortality. Preliminary results
indicate that the most important milkweed species based on monarch use vary regionally in Texas, and
that the timing of 5th generation activity (abundance of caterpillars) also varies regionally. Tachinid fly
parasitism rates were high in some locations and during some sampling periods, especially for the winter
breeding population. OE infection rates were also higher in winter breeding monarchs compared to
migrants. Two more years of data collection will provide additional insights into the observed patterns.