Behavioral Plasticity and Variation in Pit Construction of Antlion Larvae in Substrates with Different Particle Sizes

Abstract

Behavioral plasticity allows animals to maximize their fitness in a variety of environmental conditions. Trap‐building predators represent case studies in such plasticity as the characteristics of their traps are dependent upon the substrate available. We investigated the effect of sand particle size on pit construction in antlions (Euroleon nostras), sand‐dwelling insect larvae that build pitfall traps to capture prey. The pit construction behavior of the species comprises six stages. When antlions were exposed to different sand particle sizes, their behavior differed in terms of the occurrence and duration of particular stages and in the frequency of jerks produced during sand tossing. Jerk frequency was negatively correlated with sand particle size and also changed during pit construction. Furthermore, at larger particle sizes, individuals occasionally constructed irregular traps with a figure of eight shape, and they crossed the center of the truncated cone during deepening. In the largest substrate, particle size of antlions did not construct pits. Our results demonstrate that variation in traps under differing environmental conditions stems directly from behavioral plasticity in this species.

Can models of density‐dependent habitat selection be applied for trap‐building predators?

“…Recently, there has been a growing sense among ecologists, that sit-and-wait predators in general, and trapbuilding predators in particular, are capable of showing behavioral flexibility (Scharf et al 2011;Klokocovnik et al 2012), calling to examine if optimal foraging and habitat selection theories are applicable to this unique group of predators (Scharf and Ovadia 2006;Scharf et al 2011).…”

“…For example, pit-building antlions exhibit extensive variation in their preferences for soil/sand particle sizes (Morisita 1952;Botz et al 2003;Devetak et al 2005Devetak et al , 2012Devetak 2008;Barkae et al 2012). However, despite their preferences for different soil types, pit-building antlions may also construct pits in less desirable habitats (Lucas 1982;Farji-Brener 2003;Klokocovnik et al 2012). The theory of density-dependent habitat selection predicts that habitat selectivity should decline, increase or remain stable with increased density, depending on the type of population regulation (Morris 1987(Morris , 1988(Morris , 1990(Morris , 1992Rosenzweig 1991).…”

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

“…Many antlion species require a particular combination of loose soil, shelter from rain and sun, and absence of leaf litter to build their pits (Scharf & Ovadia, 2006). These microhabitat restrictions determine that larvae often be found aggregated in high densities groups known as “antlion zones” (Griffiths, 1980, 1986; Gotelli, 1993, 1996, 1997; Scharf & Ovadia, 2006; Klokočovnik et al., 2012; see also Figure 1). Thus, the role of competition in determining pit dimensions in antlion larvae could be the rule rather than the exception.…”

“…al., 2005). Therefore, antlion traps usually occur in fine‐grained (e.g., <2 mm) or loose soils with low amount of leaf litter (Wilson, 1974; McClure, 1976; Griffiths, 1980, 1986; Gotelli, 1996, 1997; Scharf & Ovadia, 2006; Scharf, Golan, & Ovadia, 2009; Klokočovnik, Devetak, & Orlačnik, 2012; but see Devetak & Arnett, 2015). These microhabitat preferences often stimulate high‐density aggregations of antlions in areas that are more favorable for pit construction (Figure 1, "antlion zones” sensu Gotelli, 1993).…”

Group dynamics and relocation decisions of a trap-building predator are differentially affected by biotic and abiotic factors

“…5), while conspecifics and sand traits are sensed by vibrations in sand, similar to antlions ( Devetak et al 2007 ). Second, it is possible that sand particle size has an effect only at a finer temporal scale, with the successive construction stages lasting for different periods of time under fine and coarse sand ( Klokočovnik et al 2012 ).…”