Optimizing the application method of entomopathogenic nematode suspension for biological control of large pine weevil Hylobius abietis

Abstract

Entomopathogenic nematodes (EPNs) are effective against the immature stages of the large pine weevil Hylobius abietis. In three field trials we compared the efficacy of the application method of EPN for weevil suppression below the suggested threshold of 20 weevils per stump: applying the EPN suspension in the top edges of the stumps ('top') vs. drenching the soil around stumps ('standard'). For Steinernema carpocapsae, weevil suppression was below the targeted threshold only when suspension was applied in the standard way (two of the three sites). On the other hand, weevil suppression was provided in all three cases of 'top' application of Heterorhabditis downesi suspension, whereas suppression in 'standard' application was observed in one site. Percentage parasitism of developing weevils in relation to depth and distance help explain EPN movement post-application. Weevil suppression relative to suggested thresholds can be improved by altering the method of EPN application depending on the nematode species.

Evaluating a Portable Method and Two Irrigation Drippers for Field Application of Entomopathogenic Nematodes

“…To make EPNs more attractive, products must be cheaper, more effective, and easier to apply. In addition to reducing production costs, studies are also carried out to increase the efficiency in field conditions and to increase the success of EPNs with new application methods (Wright et al, 2005;Beck et al, 2013;Kapranas et al, 2017;Dunn et al, 2020).…”

Efficacy of entomopathogenic fungi against large pine weevil, Hylobius abietis, and their additive effects when combined with entomopathogenic nematodes

“…In Wales, suspension was applied to the gap between the bark and stump at the top, while in Ireland it was applied to the sides of stumps and surrounding soil. Another study testing different application methods of EPN for pine weevil suppression showed that application on top vs application around the stump can have significant effects on EPN efficacy and that weevil suppression relative to suggested thresholds can be improved by altering the method of EPN application depending on the nematode species (Kapranas et al 2017b). These two application methods were tested, along with a combination of both methods.…”

Transmission Success of Entomopathogenic Nematodes Used in Pest Control

“…The distinction between species based on foraging strategy should not be over-relied on for accurately predicting field success of a species. For example, S. carpocapsae , which is classified as an ambusher, was able to infect large pine weevils ( Hylobius abietis ) under the bark of tree roots as far as 30 cm deep in the soil [ 120 ]. In this and similar examples, the nematodes may be using tree roots as “routeways” to facilitate movement through soil.…”