Open field behavior in the house cricket (Acheta domesticus): effect of illumination, sex differences and individual consistency

Abstract

Edible insects are worldwide promoted as an alternative protein, trace mineral and lipid source in animal feed and human food. The house cricket (Acheta domesticus) is already being reared at an industrial scale, yet current mass-rearing practices and facility design may still leave room for improvement. Behavioral tests have been suggested as an important assessment tool at the whole-organism level that can be used to find optimal housing conditions (e.g. density, diet, temperature). Here, we adapt the widely used open field test to the house cricket. We tested 16 male and 16 female house crickets four times under two different light intensities. Videos were analysed with Ethovision™ tracking software and variables distance moved, velocity, and duration and frequency in zone were extracted. Results showed that house crickets, like vertebrate model species, spent most time close to the walls of the arena, and crossed the center zone with high velocity. Brighter illumination was associated with increased velocity, in particular in the center zone during the first test occasion, suggesting avoidance of this zone. Male crickets had higher locomotory activity than females. Consistency repeatabilities and intraclass correlation coefficients (ICCs) were moderate to high, and the correlation between subsequent occasions became stronger over the four occasions at day 1, 2, 3 and 7. The first test occasion differed from subsequent occasions, therefore repeated testing may be necessary when analysing experimental manipulations of small effect size. Overall, the results are promising for use of the open field test as a precise phenotyping tool.