Antlions in interaction: confrontation of two competitors in limited space

Abstract

The study focused on the behaviour of sit-and-wait antlion larvae in interspecific interactions. Antlion larvae usually occur in clusters with a high density of individuals; therefore, competition can be intense. We observed two abundant antlion species, E. nostras and M. formicarius, which co-occur in some habitats. In a simple habitat choice experiment where substrates differed according to sand particle size, we found that E. nostras exhibited dominance over M. formicarius. Most E. nostras larvae remained in the more suitable substrate and constructed pits, while all the M. formicarius larvae moved out of the suitable area, and did not build pits. In the second experiment, we observed the characteristics of the pit-fall traps and scored the occurrence of larval relocation in relation to interactions and in the control group, where larvae were kept in containers separately. In interactions, the larvae of E. nostras constructed smaller pits, but pit enlargement was greater in comparison to the control group. M. formicarius larvae constructed similar sized pits in both groups; however, enlargement was greater in the control group. Relocation of larvae occurred only during interactions. In direct interactions, we found 15 behavioural patterns, which are described in detail for the first time. In the presence of a competitor, larvae showed intense territorial behaviour. We recorded several behavioural patterns during larval confrontation, and interestingly, intraguild predation rarely occurred. In most cases, E. nostras larvae outcompete M. formicarius, which was evident from the larger pits and the rate of pit-construction.

From individuals to populations: How homo‐ and heterospecific interactions influence habitat selection in a sit‐and‐wait predator

“…The question is whether one species is more competitive, which may be a behavioural trait (Klokočovnik et al, 2020), or whether the species have different habitat requirements. In habitats where the species occur separately, E. nostras always resides in protected microhabitats, while M. formicarius inhabits open, more exposed areas, usually in forests (Badano & Pantaleoni, 2014; Devetak & Arnett, 2015; Tusun & Bozdoğan, 2020).…”

“…This raises the question of whether E. nostras is more adapted to interactions or must therefore be a stronger competitor to secure space for trap construction but is more influenced by abiotic factors, in contrast to M. formicarius . Klokočovnik et al (2020) found that interactions between E. nostras and M. formicarius exerted a stronger influence on latter species. In a habitat where both species co‐occur, E. nostras occupies more favourable sites, which is likely the result of partitioning that allows the species to coexist (Adar et al, 2016; Griffiths, 1992; Polis, 1981; Schoener, 1983).…”

Evidence for competition and cannibalism in wormlions

“…This process, termed “shadow competition”, assumes that sites in the periphery of the TB predators' cluster receive more prey than sites in the center 42 – 44 . Finally, many TB predators, especially spiders and antlions, prey on whatever prey is caught in their trap, including related species and conspecifics 45 – 48 . The outcome of such cannibalistic and intra-guild predation attempts strongly depends on body size (larger individuals prey on smaller ones 22 , 49 , 50 ).…”

Disadvantages of living in a populous neighborhood for sit‐and‐wait predators: Competition for space reduces pit‐trap size in antlion larvae

“…Antlions are semi‐sessile predators and exhibit strong site fidelity because pit relocation is energetically costly (Crowley & Linton, 1999; Lucas, 1985). Hence, interactions among nearby larvae are common during pit building and maintenance (Gotelli, 1997; Devetak, 2000; Klokocovnik et al, 2020; Ovadia, Scharf, Barkae, Levi, & Alcalay, 2020). For example, co‐occurring antlion species can compete for space, showing dominance hierarchies according to sand particle size (Klokocovnik et al 2020).…”

“…Hence, interactions among nearby larvae are common during pit building and maintenance (Gotelli, 1997; Devetak, 2000; Klokocovnik et al, 2020; Ovadia, Scharf, Barkae, Levi, & Alcalay, 2020). For example, co‐occurring antlion species can compete for space, showing dominance hierarchies according to sand particle size (Klokocovnik et al 2020). Moreover, antlion larvae of different species can directly compete among them through intra‐guild predation (Ovadia et al., 2020).…”