Estimating the effect of tracking tag weight on insect movement using video analysis: A case study with a flightless orthopteran

In this study, we describe an inexpensive and rapid method of using video analysis and identity tracking to measure the effects of tag weight on insect movement. In a laboratory experiment, we assessed the tag weight and associated context-dependent effects on movement, choosing temperature as a factor known to affect insect movement and behavior. We recorded the movements of groups of flightless adult crickets Gryllus locorojo (Orthoptera:Gryllidae) as affected by no tag (control); by light, medium, or heavy tags (198.7, 549.2, and 758.6 mg, respectively); and by low, intermediate, or high temperatures (19.5, 24.0, and 28.3 degrees C, respectively). Each individual in each group was weighed before recording and was recorded for 3 consecutive days. The mean (+/- SD) tag mass expressed as a percentage of body mass before the first recording was 26.8 +/- 3.7% with light tags, 72 +/- 11.2% with medium tags, and 101.9 +/- 13.5% with heavy tags. We found that the influence of tag weight strongly depended on temperature, and that the negative effects on movement generally increased with tag weight. At the low temperature, nearly all movement properties were negatively influenced. At the intermediate and high temperatures, the light and medium tags did not affect any of the movement properties. The continuous 3-day tag load reduced the average movement speed only for crickets with heavy tags. Based on our results, we recommend that researchers consider or investigate the possible effects of tags before conducting any experiment with tags in order to avoid obtaining biased results.Web of Science167art. no. e025511

The habitat-suitability models of the European mole cricket (Gryllotalpa gryllotalpa) as information tool for conservation and pest management

The European mole cricket, Gryllotalpa gryllotalpa, feeds on a wide range of crops and can also damage plants with its burrowing activities. In suitable habitats (like those with damp, rich soils in flood plains), G. gryllotalpa numbers can increase to high levels. On the other hand, the abundance of G. gryllotalpa has dramatically decreased in north-western Europe partly due to direct eradication and excessive pest control. Using habitat suitability modelling, we identified areas suitable for G. gryllotalpa occurrence based on previous reports of its occurrence and based on environmental data. We limited our study area to regions where G. gryllotalpa is the only known Gryllotalpa species. The most important variables in our models were found to be relative air humidity and minimum soil temperature of the coldest month. We suggest that soil temperature is a limiting factor for European mole cricket occurrence in the Czech Republic because most areas in the country experience soil temperatures just below 0 °C, while most reports of G. gryllotalpa occurrence in Europe are from areas where the soil temperature does not drop below 0 °C. The models we have developed can provide information on possible occurrences of the mole cricket and thus improve the decision-making process both in the field of pest control and the conservation of this species

Estimation of the Recent Expansion Rate of Ruspolia nitidula (Orthoptera) on a Regional and Landscape Scale

Recent changes in insect distribution are consistent with the expected interacting effects of climate and habitat change. The orthopteran Ruspolia nitidula has expanded its area of distribution in Western and Central Europe in recent decades. Because males emit a sound that is easily detected at a distance of up to 40 m, it is possible to detect spreading individuals and to therefore document routes and rates of spread. Using occurrence data at the landscape scale and three methods, including least-cost path analysis with habitat suitability, we estimated the R. nitidula expansion rate from 2006 to 2020 in the Czech Republic; this involved estimating distances between two origin occurrences in 2006 and two occurrences on the area margin in 2020. For comparison, we directly monitored expansion based on detection of singing males at the regional scale at the areal margin in the Odra River basin (2016–2020). The estimated maximum expansion rate ranged from 13.8 to 16.2 km/year based on occurrence data at the landscape scale and from 11.1 to 11.7 km/year based on the monitoring of males in the Odra River basin. To our knowledge, this is the first report of the direct monitoring of individual spreading males to detect changes in the distribution of an orthopteran

Modeling the distribution of rare and interesting moss species of the family Orthotrichaceae (Bryophyta) in Tajikistan and Kyrgyzstan

Bryological research carried out from 2008 in Tajikistan and Kyrgyzstan brought interesting data on the occurrence of epiphytic bryophytes which have not been recorded yet there. One of the species was recently described as a new (Orthotrichum pamiricum) and some of the other newly recorded species are considered as rare or endangered in the region of Middle Asia. To make detailed field monitoring of the species with the aim of mapping their distribution in a wild and complex mountainous terrain, it was necessary in the first instance to identify the area with suitable conditions for the occurrence of these species. We present an innovative modeling program MaxEnt (maximum entropy modeling), which have not previously been used for modeling either epiphytic bryophytes or in the Middle Asia region. Using 205 samples (presence-only data), percent tree cover, and seven uncorrelated bioclimatic variables, regions suitable for the occurrence of the studied species were identified. Distribution models for eight most interesting species of Orthotrichum are presented here (O. affine, O. anomalum, O. crenulatum, O. cupulatum, O. pallens, O. pamiricum, O. pumilum, and O. speciosum). They indicated appropriate areas for the most probable occurrence of the species in western Tajikistan, and southwestern and northeastern Kyrgyzstan. These results could serve as guides for future survey expeditions, and aid in the conservation of target species and our understanding of their ecology. Different environmental variables for various species were selected as the most important for modeling. However, for most species higher minimum temperatures and higher precipitation in the wettest month and mean diurnal range were the variables with the greatest contribution to the models