The lure of hidden death: development of an attract-and-kill strategy against Agriotes obscurus (Coleoptera: Elateridae) combining semiochemicals and entomopathogenic nematodes

Abstract

Wireworms are polyphagous soil-dwelling pests that are hard to control. Attract-and-kill strategies, combining attractive semiochemicals with biocontrol agents, have great promise to control insect pests. We hypothesized that the combination of plant semiochemicals and entomopathogenic nematodes (EPNs) in an attract-and-kill system could greatly enhance the nematodes' efficiency against wireworms. We evaluated the potential of alginate beads loaded with plant extracts and EPNs to control Agriotes obscurus. We tested the efficiency to kill wireworms or to reduce their feeding activity when combining potato tuber extracts as attractants with any of seven different EPN populations. While a direct application of EPNs on wireworms did not reduce the feeding activity nor increased their mortality, the combination of attractants and EPNs encapsulated in alginate beads resulted in attraction and consumption of the EPNs and caused up to 50% wireworm mortality with the EPN species Steinernema carpocapsae. Beads with EPNs caused a significant reduction of the wireworms' feeding activity. This study shows that wireworms feeding on EPN-containing beads have their feeding activity and survival negatively affected. Considering their long developmental time and the survival capability of EPNs in the soil, implementing this attract-and-kill system in the field might be a suitable strategy for the long-term management of wireworms.

Influence of Wireworm Diet on its Susceptibility to and Control With the Entomopathogenic FungusMetarhizium brunneum(Hypocreales: Clavicipitaceae) in Laboratory and Field Settings

“…Even though the effects of cover crops on susceptibility to Metarhizium infection require further examination, perhaps including other plant species, it is worth recognizing forage plants as a potential factor when planning control setups. Some studies have already acknowledged this, for example in using trap crops ( Landl and Glauninger 2013 , Sharma et al 2019 ) or attract-and-kill approaches using plants ( Vernon et al 2016 ) and forage search triggers ( Brandl et al 2017 , La Forgia et al 2021 ). Nevertheless, to successfully include selected forage crops in the plant protection system, it is necessary to further assess wireworm feeding behavior and to understand the underlying mechanisms of the effects of plant diet on wireworm survival.…”

Integrated Pest Management of Wireworms (Coleoptera: Elateridae) and the Rhizosphere in Agroecosystems

“…Kabaluk et al [201] used germinating wheat seeds coated with M. anisopliae as a bait trap against A. obscurus in the field. Finally, in the laboratory, alginate beads loaded with a combination of potato extract (as an attractant) and EPN (either S. carpocapsae or H. bacteriophora) were effective in attracting and killing A. obscurus [225].…”

Evaluation of Entomopathogenic Nematodes against Common Wireworm Species in Potato Cultivation

“…For many years, chemical insecticides with broad-spectrum active ingredients such as organochlorine, organophosphates, and carbamates have been the main strategy to control wireworms by most producers. However, restrictions and bans in recent decades on the use of many of these synthetic chemicals, due to environmental and health concerns, have led many researchers to search for eco-friendly alternatives to synthetic insecticides for the management of wireworm populations [ 11 , 12 , 13 , 14 ]. Among new ecologically based approaches, entomopathogenic nematodes (EPNs) (Steinernematidae and Heterorhabditidae) have recently attracted a great deal of attention due to their biocontrol potential against many economically important insect pests [ 15 , 16 , 17 ].…”