Biology of Taeniopoda eques (Orthoptera: Acrididae) in Southeastern Arizona

Abstract

Life history parameters are given for Taeniopoda eques (Burmeister) including habitat characterization, distribution, phenology, morphometrics, diet, and natural enemies. Molting, mating, oviposition, dispersal, daily, thermoregulatory, and disturbance behaviors are examined. Hatching and abundance for this desert dweller are closely linked to onset of summer rains and appearance of ephemeral food plants. Times from egg hatch to adult, mating, oviposition, and death are ca. 39, 56, 74, and 105 days, respectively. Five instars are distinguished by pronotum length, head width, and wing pad development. Fresh eggs weigh 0.029 g; 40-day-old adult males, 2.75 g; females, 8.26 g. Molting is primarily diurnal, but extends past sunset on warm nights. Temperature influences molting success; no molting occurred at temperatures below 22°C. The molt to adult requires 86.8 min at 30°C. Both sexes mate repeatedly. Males are sexually aggressive, females passive. During the long copulation (ca. 14.1 h) multiple spermatophores are passed. Females oviposit diurnally 4–8 cm deep in soil under shrubs. T. eques feeds mainly on low-growing desert annuals, but takes dead or incapacitated arthropods, feces, or raindrops. First instars aggregate strongly; later instars weakly. A cyclical daily movement into and out of nonfood shrubs is thought to alleviate predator and thermal pressures. Male movement exceeded that of females. Beauveria bassiana and other microorganisms were found in moribund grasshoppers. T. eques is chemically protected from some predators. Aggregation, aposematism, and noisy expulsion of an odorous secretion from metathoracic spiracles advertise and reinforce chemical defense.