Bionomy of small spruce bud scale, Physokermes hemicryphus (Dalman) (Hemiptera: Coccidae) in Serbia

Abstract

Small spruce bud scale, Physokermes hemicryphus (Dalman) (Hemiptera: Coccidae), is a Holarctic, oligophagous species developing on plants of the genera Picea and Abies (Pinaceae). It is a serious pest of Picea abies in Serbia, which causes drying and falling of needles, branches and even drying of entire plants. A study of the bionomy of Ph. hemicryphus was carried out at five locations in Serbia in 2016 and 2017. Ph. hemicryphus was found to develop one generation annually and to overwinter as second-instar larvae on spruce branches. Adults emerge at the beginning of April and oviposition takes place at the beginning of May. Larvae hatch in the second half of May; during summer they feed on spruce needles and moult into second-instar larvae in September. Scale populations are controlled by a number of natural enemies. Five species of parasitoid wasps were reared: Coccophagus lycimnia (Walker) (Hymenoptera: Aphelinidae), Metaphycus unicolor Hoffer, Microterys lunatus (Dalman), Pseudorhopus testaceus (Ratzeburg) (Hymenoptera: Encyrtidae) and Pachyneuron muscarum (L.) (Hymenoptera: Pteromalidae), as well as five predatory species: Anthribus nebulosus Forster (Coleoptera: Anthribidae), Exochomus quadripustulatus L., Scymnus abietis Paykull, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). The most efficient parasitoid of Ph. hemicryphus was P. testaceus, reducing scale populations up to 28.97%, while the most efficient predator was A. nebulosus with an efficacy of up to 51.72%.

Geographical Distribution and Long-Term Monitoring of Physokermes hellenicus (Hemiptera: Coccomorpha: Coccidae) on Abies spp. (Pinales: Pinaceae) in Greece

“…In the present study, P. testaceus appeared to be the most abundant natural enemy of P. hellenicus in Greece, as reported in our previous study [16]. Additionally, P. testaceus constitutes an important natural enemy of other Physokermes species such as P. hemicryphus in Greece and Serbia [15,17] and P. piceae in Serbia [12,41]. Recently, a trophic interaction among P. hemicryphus, P. testaceus and A. nebulosus has been described in Serbia [41], a relation that should be also investigated in the case of P. hellenicus.…”