Japanese stiltgrass is an invasive plant that was accidentally introduced to the United States in the early 1900s. It can be found on roadsides and in forests, and it has many impacts on native plants and animals. Biologists Jayna DeVore and John Maerz studied the effect of Japanese stiltgrass on American toads in their natural habitat. They enclosed American toads in cages with lycosid spiders and/or Japanese stiltgrass. The four treatments were (A) lycosid spiders and Japanese stiltgrass, (B) lycosid spiders without Japanese stiltgrass, (C) lycosid spiders and Japanese stiltgrass, and (D) no lycosid spiders and no Japanese stiltgrass. They compared the survival of American toads across the treatments (left graph). They also measured the density of lycosid spiders in different areas where Japanese stiltgrass was absent vs. present (right graph).
Source: DeVore, J. L., & Maerz, J. C. (2014). Grass invasion increases top‐down pressure on an amphibian via structurally mediated effects on an intraguild predator. Ecology, 95(7), 1724-1730.
-American toads consume insects. An American toad that is consuming herbivorous insects is considered a
A) secondary consumer.
B) primary consumer.
C) primary producer.
D) tertiary consumer.

Question

Japanese stiltgrass is an invasive plant that was accidentally introduced to the United States in the early 1900s. It can be found on roadsides and in forests, and it has many impacts on native plants and animals. Biologists Jayna DeVore and John Maerz studied the effect of Japanese stiltgrass on American toads in their natural habitat. They enclosed American toads in cages with lycosid spiders and/or Japanese stiltgrass. The four treatments were (A) lycosid spiders and Japanese stiltgrass, (B) lycosid spiders without Japanese stiltgrass, (C) lycosid spiders and Japanese stiltgrass, and (D) no lycosid spiders and no Japanese stiltgrass. They compared the survival of American toads across the treatments (left graph). They also measured the density of lycosid spiders in different areas where Japanese stiltgrass was absent vs. present (right graph).
  Source: DeVore, J. L., & Maerz, J. C. (2014). Grass invasion increases top‐down pressure on an amphibian via structurally mediated effects on an intraguild predator. Ecology, 95(7), 1724-1730.
-American toads consume insects. An American toad that is consuming herbivorous insects is considered a
A) secondary consumer. 
B) primary consumer. 
C) primary producer. 
D) tertiary consumer.

Quizplus · Accepted Answer

American toads are considered secondary consumers because they eat herbivorous insects, which are primary consumers. Primary consumers eat primary producers (plants), so when a toad eats these insects, it is one step up the food chain, making it a secondary consumer.

Japanese Stiltgrass Is an Invasive Plant That Was Accidentally Introduced