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

TEJADA, DANIELA MADRIGAL; SOTO?HUAIRA, MAYORI; FARJI?BRENER, ALEJANDRO G.; CENTENO?ALVARADO, DIEGO; GUTIÉRREZ?CRUZ, SEBASTIÁN; JUNCOSA?POLZELLA, AGOSTINA S.; HERNÁNDEZ?SOTO, MARIANA

ETHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

0179-1613

The study of how trap design responds to biotic and abiotic conditions can help tounderstand the selective forces affecting the foraging of trap-building organisms.We experimentally tested whether pit design can be modified by intraspecific competitionfor space in larvae of Myrmeleon crudelis, a common sit-and-wait predatorthat digs conical pit traps in the soil to capture walking arthropods. In a tropical forestin Costa Rica, we measured pit dimensions, larval body size, and the level of competition(i.e., density of neighboring traps) in 40 antlion larvae. These larvae were thentaken to the laboratory and allowed to build new traps in individual containers. Wemeasured within-individual changes in the size of traps in the field and in the laboratory,and related these to the level of competition experienced in the field. Larvaewith relatively high levels of competition in the field showed a greater increase inthe size of their pits in the laboratory. This change was independent of larval size.Larvae with none or few neighbors in the field showed little change in their pit sizes,whereas those with higher competition levels increased their diameter and depthup to 1,400% and 1,000%, respectively. Our results demonstrate that, at least inhigh-density aggregations, pit design is restricted by competition in addition to theconstraints imposed by body size. This work suggests that biotic interactions canplay a role in the design of extended phenotypes in sit-and-wait predators that livein dense aggregations.