Ecotoxicology-model
Guides
Onthophagus nuchicornis
Small black-and-brown Dung Beetle
Onthophagus nuchicornis is a Palearctic dung beetle introduced to North America in the 1840s, now established across Canada and the northern United States. The species exhibits generalist coprophagy, successfully reproducing using dung from both domestic livestock and indigenous mammals including bobcat, moose, red fox, and raccoon. It possesses an obligatory cold reproductive diapause restricting it to a single generation per year. In the United Kingdom, it is listed as Vulnerable, while in North America it is abundant and has been employed as a model organism for ecotoxicological studies of ivermectin effects on dung burial behavior.
dung-beetleintroduced-speciescoprophagediapauseecotoxicology-modelpasture-ecosystemsexual-dimorphismivermectin-effectsgeneralist-feederPalaearctic-nativeNearctic-introducedsingle-generation-per-yearbrood-balltunneling-behaviorcompetition-with-native-speciesCLIMEX-bioclimatic-modelnutrient-cyclingsoil-aerationcattle-pasture-managementVulnerable-(UK)Triops longicaudatus
Longtail Tadpole Shrimp, American Tadpole Shrimp, Rice Tadpole Shrimp
Triops longicaudatus is a freshwater branchiopod crustacean commonly known as the longtail tadpole shrimp or rice tadpole shrimp. It inhabits ephemeral ponds and pools across western North America, South America, Japan, South Korea, and Pacific Islands. The species is notable for its ancient lineage—morphologically unchanged for over 170 million years—and its remarkable desiccation-resistant eggs that can survive decades in dry sediment before hatching upon rehydration. It displays multiple reproductive strategies including parthenogenesis, hermaphroditism, and sexual reproduction. In California agriculture, it is a significant early-season pest of rice, damaging germinating seeds in flooded fields.