ABSTRACT
Host-plant phenology can directly and indirectly mediate the abundance of insect herbivores. Our objective was to determine how host-plant flowering phenology shapes a facultative ant-lycaenid mutualism. The focus of our research was the hops azure, Celastrina humulus Scott & D. Wright, a rare species whose larvae feed on the pollen-bearing inflorescences of Humulus lupulus var. neomexicanus. We used several approaches to evaluate the role of host-plant flowering phenology in this system. First, we monitored larvae over three study years (2020-2022) to parse the role of host-plant flowering phenology and other factors in shaping the likelihood of ant tending. Second, we tested larval performance at various phenological stages of the host plant. We also quantified variation in soluble proteins and secondary metabolites among inflorescences at varying phenological stages. Lastly, we treated artificial sugar-protein baits with extracts from different phenological stages of the host plant; this allowed us to assess how chemical variation among stages could impact ant recruitment. Monitoring results revealed that the likelihood of ant tending was lowest for larvae on host plants with early-stage inflorescences. These floral stages had the greatest concentrations of both soluble proteins and α-acids (humulone and cohumulone), and in the feeding trial, early-stage flowers enabled greater weight gain for larvae. However, extracts from early-stage flowers reduced ant recruitment to sugar-protein baits. Altogether, these results suggest that early-stage inflorescences enhance larval growth while also reducing the recruitment of mutualist ants. This shows an indirect mechanism whereby changing host-plant phenology can mediate herbivore populations through interactions with ants.
Subject(s)
Ants , Butterflies , Humulus , Animals , Symbiosis , Larva , Plants , SugarsABSTRACT
White-nose syndrome (WNS) has caused the death of millions of bats, but the impacts have been more difficult to identify in western North America. Understanding how WNS, or other threats, impacts western bats may require monitoring other roosts, such as maternity roosts and night roosts, where bats aggregate in large numbers.Little brown bats (Myotis lucifugus) are experiencing some of the greatest declines from WNS. Estimating survival and understanding population dynamics can provide valuable data for assessing population declines and informing conservation efforts.We conducted a 5-year mark-recapture study of two M. lucifugus roosts in Colorado. We used the robust design model to estimate apparent survival, fidelity, and abundance to understand population dynamics, and environmental covariates to understand how summer and winter weather conditions impact adult female survival. We compared the fidelity and capture probability of M. lucifugus between colonies to understand how bats use such roosts.Overwinter survival increased with the number of days with temperatures below freezing (ß > 0.100, SE = 0.003) and decreased with the number of days with snow cover (ß < -0.40, SE < 0.13). Adult female fidelity was higher at one maternity roost than the other. Overwinter and oversummer adult female survival was high (>0.90), and based on survival estimates and fungal-swabbing results, we believe these populations have yet to experience WNS.Recapture of M. lucifugus using antennas that continuously read passive integrated transponder tags allows rigorous estimation of bat population parameters that can elucidate trends in abundance and changes in survival. Monitoring populations at summer roosts can provide unique population ecology data that monitoring hibernacula alone may not. Because few adult males are captured at maternity colonies, and juvenile males have low fidelity, additional effort should focus on understanding male M. lucifugus population dynamics.
ABSTRACT
A Preble's meadow jumping mouse (Zapus hudsonius preblei) parasitized by five grey flesh fly (Wohlfahrtia vigil) larvae was discovered at the United States Air Force Academy in Colorado Springs, Colorado (USA), in June 1998. This is the first documented case of grey flesh fly parasitism of jumping mice (Family Dipodidae). The lesion was approximately 6 mm wide and was partially hidden under a mat of wet fur. Myiasis was found in one (0.7%) of 146 jumping mice captured at the Academy in 1998. The Preble's meadow jumping mouse is considered a threatened subspecies by the United States Fish and Wildlife Service. Although grey flesh fly myiasis can be fatal, it is unknown whether it is affecting populations of Preble's meadow jumping mouse. This is the first report of grey flesh fly myiasis in free-ranging wildlife in Colorado.
