With no mouth opening and no way to poop, sand-trapper ant lions minimize their intake of anything indigestible.
When the hook pierces prey, the ant lion injects venom and digestive enzymes via the grooves.
The gut of a larval ant lion dead-ends partway through its body.
Caption: Ant lion species that hunt in sand traps have evolved extreme eating habits that prevent grit from infiltrating their food.
For ant lions, little is known of adult behavior or oviposition preferences, but these may well contribute to species coexistence, particularly since larval interactions do not indicate any obvious niche partitioning.
For larval ant lions, coexistence is enhanced because the presence of third-instar larval pits generates interstitial habitat for first-instar larvae, and because density-dependent mortality among first-instar larvae is weak [ILLUSTRATION FOR FIGURE 5 OMITTED].
In this paper, I describe the results of six manipulative field experiments and one laboratory experiment designed to test for the effects of intraguild predation on the coexistence of two species of larval ant lion (Neuroptera: Myrmeleontidae).
Ant lion larvae are ideal for studying species coexistence.
Within the ant lion zone, there is no spatial segregation of the two species, although their numbers are negatively correlated in small-quadrat samples (Gotelli 1993).
However, field experiments reveal that ants can detect and effectively avoid high-density ant lion aggregations (Gotelli 1996).
The analysis of pitfall traps revealed consistently fewer ants in the presence of ant lions [ILLUSTRATION FOR FIGURE 2 OMITTED].
A variety of circumstantial evidence suggests that dense aggregations of ant lion predators affect the distribution and abundance of ants: forager abundance in pitfall traps was consistently lower in the presence of ant lions [ILLUSTRATION FOR FIGURE 2 AND 4 OMITTED], and the rarefaction analysis suggested that the difference represented a random sample of individuals from the assemblage [ILLUSTRATION FOR FIGURE 4 OMITTED].
The experiments also provide insight into the particular cues used by ants to avoid ant lions. Avoidance does not seem to be based on the physical structure of the ant lion trap because ants established foraging trails and recruited, though at reduced numbers, across a patch of artificial ant lion pits [ILLUSTRATION FOR FIGURE 6c OMITTED].
Ants are the most common arthropod in pitfall trap catches, and represent a potentially important food source for ant lions. The avoidance behavior by common ant species may substantially reduce food resources for ant lions.
The current study suggests that generalist ant predators, such as ant lions, can have community-wide impacts on distribution, abundance, and behavior of ground-foraging ants.