Biological control of wood destroying beetles with Spathius exarator

Abstract: Biological control using beneficial organisms is known for decades and now getting important in Integrated Pest Management. An efficient strategy in fighting the furniture beetle Anobium punctatum is based on the parasitoid Spathius exarator. This wasp parasitizes the beetle larvae by piercing its ovipositor through the wood followed by oviposition. After devouring and killing the host, the wasp pupates and hatches as adult through a self-gnawed 0.5 mm-hole. Thus, each new S. exarator hole is equivalent to one killed beetle larva. As the wasp holes clearly can be distinguished from the 2 mm-hole of A. punctatum, we are able to observe the treatment success. Until 2019, we successfully released S. exarator into more than 130 A. punctatum infested objects. At least twelve treatments within three years were performed. On exactly defined areas, new exit holes of A. punctatum and S. exarator were counted and parasitation rate was calculated. Here we present pooled data of 46 A. punctatum infested churches, successfully treated and monitored over a period of one to six years. Furthermore, as a representative sample, we show the results of one church treated and concomitantly monitored for eight years.Laboratory experiments showed that S. exarator also parasitizes larvae of the powderpost beetle Lyctus brunneus. Hence, S. exarator might be a candidate to control this wood pest as well.