Journal of Insect Conservation Survival of eggs to third instar of late-summer and fall-breeding monarch butterflies (Danaus plexippus) and queen butterflies (Danaus gilippus) in north Texas

Abstract

Introduction: Eastern migratory monarch butterflies (Danaus plexippus) have declined over 80% in recent years, but little is known about fall reproduction in the southern U.S. where monarchs may compete with queen butterflies (Danaus gilippus). Aims/Methods: We provide data on the survival to third instar, associated arthropods, and phenology of fall breeding monarchs and queens in Texas. Results: Monarch and queen survival was high, but varied among years. Oleander aphids (Aphis nerii), jumping spiders (Salticidae), and red imported fire ants (Solenopsis invicta) had minor negative effects on survival. The abundance of monarchs and queens on the study site peaked three to four weeks before the main passage of monarchs in the area. Queens had similar phenology and exhibited a migratory pattern similar to monarchs but on a smaller scale. Discussion: Survival of fall monarchs is high and likely to be important for winter roost recruitment. Fall egg survival was not greatly affected by any particular arthropod taxon, but may be affected by precipitation. Fall reproduction is a response to available host plants and likely adaptive. The timing of oviposition enables pupae to eclose in time for successful migration to winter roosts. Implications for Insect Conservation: Management of Asclepias viridisand other native milkweeds to facilitate fall reproduction is important for the recovery of monarchs because it buffers variable productivity occurring further north and contributes significantly to overwintering populations. Management should use mowing and burn schedules that promote high quality host plants. Populations of queens should be monitored for their potential to compete with monarchs especially in response to the potential impacts of parasite resistance and climate change.

Butterfly abundance is higher in areas treated for fire ants

“…Calvert (2004) later reported that monarch larval survival is higher within small exclosures (~20 m 2 ) treated for fire ants than outside. In contrast, other researchers in Texas reported that a higher percentage of monarchs survived to third instars closer to red imported fire ant mounds than farther away from fire ant mounds (Hudman 2018) and that fire ants had no significant effect on fifth instar survival (Scott 2019). Monarch survival from egg to fifth instar is very low (7–10%; Nail et al 2015) even in areas without fire ants, so it is not clear if fire ants decreased monarch survival, or if fire ants removed or replaced other predators (Calvert 2004, Hudman 2018).…”

Milkweed and floral resource availability for monarch butterflies (Danaus plexippus) in the United States

“…Conservation practitioners would also benefit from an improved understanding of how monarchs and pollinators interact with habitats of varying quality. We recognize that the sites surveyed and flowering species documented may not offer equal value to monarchs (Nail et al, 2015;Grant et al, 2020;Antonsen et al, 2021;Bruce et al, 2022;Scott et al, 2023). The IMMP's surveys of adult and immature monarchs offer opportunities to explore such relationships.…”