The role of spiders as biological control agents in greenhouse crops – preliminary study

Abstract: In recent years, more attention has been paid to generalist predators in biological
pest control of greenhouse crops due to their potential to target a wide range of pest species that persist year-round in the cropping system. This potential is enhanced by provisioning
supplementary food sources for these predators. Among generalist predators, spiders are wellknown for their predatory capabilities, however their role in pest in management remains
understudied.
In our research, we evaluated the potential of three Linyphiidae spider species for pest
control: the dwarf spider, Erigone dentosa O.P.-Cambridge, the sheetweb spider, Ostearius
melanopygius (O.P.-Cambridge), and the sheet weaver spider, Mermessus denticulatus
(Banks). All spider predators were preventively introduced into ornamental crops and
supplemented with additional food when needed. The targeted pests were Lyprauta cambria
(Diptera: Keroplatidae) and Thrips parvispinus (Thysanoptera: Thripidae) in Phalaenopsis
(moth orchid) and Anthurium (laceleaf), respectively, and Empoasca decipiens (Hemiptera:
Cicadellidae) and Frankliniella occidentalis (Thysanoptera: Thripidae) in Amaryllis. All four
species remain key pests of these respective crops, causing economic damage and increasing
pesticide use.
The pest suppression by the spiders was assessed by following pest population dynamics,
whereas gut-content analysis of the spiders was performed to confirm predation. In the
experiment, a spontaneously-appearing Theridiidae spider predated on L. cambria. Two of the tested spiders consumed E. decipiens, T. parvispinus and F. occidentalis and contributed to a reduction in pest populations.
This study provides preliminary insights into the potential role of spiders as biological
control agents in greenhouse crops, opening the way for further research into their efficacy and integration into pest management strategies.