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. 2021 Aug 1;11(17):11903-11914.
doi: 10.1002/ece3.7956. eCollection 2021 Sep.

Preliminary assessment of cavity-nesting Hymenopterans in a low-intensity agricultural landscape in Transylvania

Károly Lajos  1 , Imre Demeter  1 , Róbert Mák  1 , Adalbert Balog  2 , Miklós Sárospataki  1
Affiliations

Preliminary assessment of cavity-nesting Hymenopterans in a low-intensity agricultural landscape in Transylvania

Károly Lajos et al. Ecol Evol. .

Abstract

In this study, our aim was to assess several traits of cavity-nesting Hymenopteran taxa in a low-intensity agricultural landscape in Transylvania. The study took place between May and August 2018 at eight study sites in the hilly mountainous central part of Romania, where the majority of the landscape is used for extensive farming or forestry. During the processing of the trap nest material, we recorded several traits regarding the nests of different cavity-nesting Hymenopteran taxa and the spider prey found inside the nests of the spider-hunting representatives of these taxa. We also evaluated the relationship between the edge density and proportion of low-intensity agricultural areas surrounding the study sites and some of these traits. The majority of nests were built by the solitary wasp genus Trypoxylon, followed by the solitary wasp taxa Dipogon and Eumeninae. Solitary bees were much less common, with Hylaeus being the most abundant genus. In the nests of Trypoxylon, we mostly found spider prey from the family of Araneidae, followed by specimens from the families of Linyphiidae and Theridiidae. In the nests of Dipogon, we predominantly encountered spider prey from the family of Thomisidae. We found significant effects of low-intensity agricultural areas for the genera of Auplopus, Megachile, Osmia, and the Thomisid prey of Dipogon. We also found that the spider prey of Trypoxylon was significantly more diverse at study sites with higher proportions of low-intensity agricultural areas. Our results indicate that solitary bees seem to be more abundant in areas, where the influence of human activities is stronger, while solitary wasps seem to rather avoid these areas. Therefore, we suggest that future studies not only should put more effort into sampling in low-intensity agricultural landscapes but also focus more on solitary wasp taxa, when sampling such an area.

Keywords: landscape context; solitary bees; solitary wasps; spider prey; spider‐hunting wasps; trap nests.

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Conflict of interest statement

The authors of this article have no financial or other conflict of interest to declare.

Figures

FIGURE 1
FIGURE 1
Typical landscape in the study area
FIGURE 2
FIGURE 2
A trap nest, mounted to a tree branch
FIGURE 3
FIGURE 3
Relationship between the number of wasp and bee nests at the eight study sites. The dashed blue line represents a generalized linear model (GLM) assuming a Poisson distribution, fitted to the data points
FIGURE 4
FIGURE 4
Principal component analysis (PCA) biplot of the nest numbers of the cavity‐nesting Hymenopteran taxa per site. The length of the arrows represents the strength of the association with the study sites
FIGURE 5
FIGURE 5
Diameter of the reed stalks with nests for the seven cavity‐nesting Hymenopteran taxa found at our study sites. The horizontal lines indicate the median value. The lower and upper whiskers represent the maximum values of the data that are within 1.5 times the interquartile range under the 25th and over the 75th percentile, respectively. Outlier values, indicated by black dots, are any values under or over this range. Same letters indicate no statistical differences between groups (Tukey's HSD test, p < 0.05)
FIGURE 6
FIGURE 6
Principal component analysis (PCA) biplot of the numbers of Trypoxylon (Try) and Dipogon (Dip) spider prey per site. The length of the arrows represents the strength of the association with the study sites
See this image and copyright information in PMC

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