Range-Expansion in Processionary Moths and Biological Control

Abstract

<jats:p>Global climate change is resulting in a wide range of biotic responses, including changes in diel activity and seasonal phenology patterns, range shifts polewards in each hemisphere and/or to higher elevations, and altered intensity and frequency of interactions between species in ecosystems. Oak (Thaumetopoea processionea) and pine (T. pityocampa) processionary moths (hereafter OPM and PPM, respectively) are thermophilic species that are native to central and southern Europe. The larvae of both species are gregarious and produce large silken ‘nests’ that they use to congregate when not feeding. During outbreaks, processionary caterpillars are capable of stripping foliage from their food plants (oak and pine trees), generating considerable economic damage. Moreover, the third to last instar caterpillars of both species produce copious hairs as a means of defence against natural enemies, including both vertebrate and invertebrate predators, and parasitoids. These hairs contain the toxin thaumetopoein that causes strong allergic reactions when it comes into contact with human skin or other membranes. In response to a warming climate, PPM is expanding its range northwards, while OPM outbreaks are increasing in frequency and intensity, particularly in northern Germany, the Netherlands, and southern U.K., where it was either absent or rare previously. Here, we discuss how warming and escape from co-evolved natural enemies has benefitted both species, and suggest possible strategies for biological control.</jats:p>

Climate change‐mediated temperature extremes and insects: From outbreaks to breakdowns

“…The oak processionary moth favors warm microclimates, especially in late winter and early spring and has clearly benefitted from the practice of growing oak trees in strips along roads where thermoregulation is optimized. Moreover, natural enemies such as the ground beetle Calasoma sycophanta and specialized dipertan and hymenopteran parasitoids have not apparently tracked the northward expansion of the oak processionary moth (De Boer & Harvey, 2020).…”

Role of Egg Parasitoids in Controlling the Pine Processionary Moth in the Cedar Forests of Chréa National Park (Algeria)

“…Of the parasitoid species found in our study, B. servadeii and O. pityocampae, are the most abundant and best studied. B. servadeii is a specialist of PPM while O. pityocampae is a generalist egg parasitoid, requiring an alternant host species to complete its first generation before PPM eggs are available [50]. T. embryophagum has a wide host range and is frequently mass reared for augmentative biological control of many insect pests in agricultural and forestry environments [51,52].…”

„Eichen sollst Du weichen“ – Eichenprozessionsspinner als potenzielle Gefahr

“…Der weibliche Eichenprozessionsspinner legt in älteren Eichen 100-200 Eier ab. Bis zum Herbst entwickelt sich im Ei eine Jungraupe, die in dieser Form überwintert, dabei Temperaturen bis zu − 30 C° [2] überlebt und Anfang Mai schlüpft. Die Raupen leben in Gruppen von 20-30 Tieren und treten typischerweise im "Gänsemarsch" auf, wenn sie sich nachts auf Nahrungssuche befinden oder sich verpuppen wollen [2], woher auch der Name "Prozessions-"spinner kommt (▶ Abb.…”

“…Diese namensgebende Prozession kann bis zu 10 m lang sein [3]. In den Raupennestern (Gespinsten) der Eiche, die als Rückzugsort dient [2], kommt es zur Häutung. Jüngere Raupenstadien bilden kleine Blattgespinste im oberen Kronenbereich, während ältere Raupen (ab dem 5.…”