The impact of local spatial resistance on the movement behaviour of Tenebrio molitor L.

Abstract

AbstractAlthough the impact of vegetation and other environmental factors on the distribution of terrestrial invertebrates has been known since the 1950s, basic knowledge about their interaction with micro-landscape elements is lacking. In experimental model systems, the impact of varying local spatial resistance (LSR) on the distribution of Tenebrio molitor individuals was analysed in the laboratory. In the setups, LSR led to a reduction of the average distance covered (move step length) and a reduction of the velocity (the maximum speed ranging from 36.1 in the control groups to 20.4 [mm*step−1] in areas with a maximum LSR). Also, the covered distances per individual varied among three groups, from 2.97 m in the control to 1.11 m in areas with medium LSR to 0.88 m in areas with maximum LSR. Thus, in areas with LSR, animals were forced by their habitats to perform shorter move steps on average and covered less distance. The distance covered (i.e., dispersal performances) were not correlated with such factors as sex, weight and length of the Tenebrio individuals from other studies. Analysis of the data for net squared displacement indicated that the dispersal of the beetles did not follow a diffusion process. The move step directions of the dispersal data showed pronounced autocorrelation, which means that in contrast to other findings, the individuals were not performing a random walk. This effect was strongly dependent on the temporal resolution (i.e. grain), and was also influenced by the experimental conditions. The entire array of data showed high variability among the sub-groups (as well as many outliers), revealing nonparametric characteristics. The results showed that the specific physical configuration of suitable habitat for Tenebrio is one of the key indicators of landscape connectivity on the micro-scale.