Spinosad and spinetoram disrupt the structure and the abundance of ground-dwelling arthropod communities in herbaceous fields

ABSTRACT

In the present study, the effects of spinosad, spinetoram and chlorpyrifos on ground-dwelling arthropod diversity and abundance were compared in a herbaceous field in order to evaluate their relative compatibility with conservation of arthropod densities. Ten different treatments of spinosad, spinetoram, and chlorpyrifos, which was used as a toxic reference, were allocated at random to experimental plots. A total of 101,119 individuals of epigeal arthropods belonging to 18 orders and suborders were captured in pitfall traps, with the most abundant taxa Hymenoptera, Collembola, Araneae, Acari, Coleoptera, Isopoda, Julida and Opiliones. The orders Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones were identified to the family or species level. Gnaphosidae, Carabidae, Entomobryidae, Formicidae and Metaplatybunus grandissimus CL Koch (Phalangiidae) were the most abundant taxa of Araneae, Coleoptera, Collembola, Hymenoptera and Opiliones, respectively. Significant density reduction was observed for Gnaphosidae, Linyphiidae (Araneae), Carabidae, Entomobryidae, Formicidae and M. grandissimus after chlorpyrifos treatment. Formicidae individuals were significantly reduced after spinosad application, while the Entomobryidae and M. grandissimus individuals were reduced after the application of both spinosad and spinetoram. Our results showed no significant differences in diversity level of orders and suborders as well as of Araneae families between the spinetoram-treated plots at both concentrations tested and the control. In contrast, a significant difference in the diversity of Coleoptera was detected between the spinetoram treatments and the control. Our findings showed that spinosad and spinetoram may disrupt the structure and the abundance of surface-active arthropod fauna causing considerable changes in the ground-dwelling biodiversity of this ecosystem.

KEYWORDS:

• Spinosad
• Spinetoram
• chlorpyrifos
• pitfall traps
• non-target effects

Acknowledgments

We thank Dr Maria Chatzaki (Department of Molecular Biology and Genetics, Democritus University of Thrace, Greece) and Dr Dávid Murányi (Department of Zoology, Hungarian Natural History Museum) for their valuable help in the identification of Araneae and Opiliones individuals, respectively. We are also grateful to Prof. G. Kamari and V. Karagianni (Department of Biology, University of Patras) for confirming the identifications of weeds. Trade names or commercial products mentioned in this publication is solely for scientific information and does not imply recommendation by the Technological Educational Institute of Ionian Islands, the Agricultural University of Athens, the University of Thessaly and the Benaki Phytopathological Institute.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the State Scholarships Foundation of the Hellenic Republic.