Monarch butterfly (Danaus plexippus L.) declines in eastern North America have prompted milkweed host plant restoration efforts in non-agricultural grasslands. However, grasslands harbor predator communities that exert high predation pressure on monarch eggs and larvae. While diurnal monarch predators are relatively well known, no studies have investigated the contribution of nocturnal monarch predators. We used video cameras to monitor sentinel monarch eggs and fourth instars on milkweed in southern Michigan to identify predators and determine if nocturnally-active species impose significant predation pressure. We observed ten arthropod taxa consuming monarch eggs and larvae, with 74% of egg predation events occurring nocturnally. Taxa observed attacking monarch eggs included European earwigs (Forficula auricularia L.), tree crickets (Oecanthus sp.), lacewing larvae (Neuroptera), plant bugs (Miridae), small milkweed bugs (Lygaeus kalmii Stal), ants (Formicidae), spiders (Araneae: Salticidae and other spp.), harvestmen (Opiliones), and velvet mites (Trombidiformes: Trombidiidae). Larvae were attacked by ground beetles (Calleida sp.), jumping spiders (Araneae: Salticidae), and spined soldier bugs (Podisus maculiventris Say). Our findings provide important information about monarch predator-prey interactions that could be used to develop strategies to conserve monarchs through reducing predation on early life stages.
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Intraspecific variation in responses to aposematic prey in a jumping spider ( Phidippus regius )
Abstract Aposematic signals often allow chemically defended prey to avoid attack from generalist predators, including jumping spiders. However, not all individual predators in a population behave in the same way. Here, in laboratory trials, we document that most individualPhidippus regiusjumping spiders attack and reject chemically defended milkweed bugs (Oncopeltus fasciatus), immediately releasing them unharmed. However, a small number of individuals within the population kill and completely consume these presumably toxic prey items. This phenomenon was infrequent with only 14% of our sample (17/122) consuming the milkweed bugs over the course of the study. Individuals that killed and consumed bugs often did so repeatedly; specifically, individuals that consumed a bug in their first test were more likely to kill a bug in their second test and also tended to consume them again. We explored what might drive some (but not all) individuals to consume these bugs and found that neither sex, sexual maturity, body size, laboratory housing type, nor being wild‐caught or being laboratory‐reared, predicted milkweed bug consumption. Consuming bugs had no negative effects on spider mass or body condition; contrary to expectations, individuals that consumed milkweed bugs actually gained more body mass and increased in body condition. We discuss potential behavioural and physiological variation between individuals that may drive these rare behaviours and the implications for the evolution of prey defences.
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- Award ID(s):
- 1831751
- PAR ID:
- 10455248
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ethology
- Volume:
- 126
- Issue:
- 12
- ISSN:
- 0179-1613
- Page Range / eLocation ID:
- p. 1089-1097
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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