Diversity of Ooencyrtus spp. (Hymenoptera: Encyrtidae) parasitizing the eggs of Stenozygum coloratum (Klug) (Hemiptera: Pentatomidae) with description of two new species.

Shahar Samra,Emilio Guerrieri,John Noyes,Pasquale Cascone,Alex Protasov,Zvi Mendel,Murad Ghanim,Bi-Song Yue

doi:10.1371/journal.pone.0205245

Abstract

Ooencyrtus spp. (Hymenoptera, Chalcidoidea, Encyrtidae) are important natural enemies of agricultural and forest insect pests, and are distributed worldwide. Their reduced dimensions, highly variable morphological characters and possible effect of wide host range and abiotic factors, make correct identification at the species level particularly difficult. This paper combined molecular, morphological, and biological data to characterize a group of Ooencyrtus spp. emerging from the eggs of the variegated caper bug, Stenozygum coloratum in the east Mediterranean area. COI and ITS2 sequencing revealed the presence of six and five divergent clades, respectively. Three clades were identified as Ooencyrtus telenomicida, Ooencyrtus pityocampae and O. pistaciae. Two clades represent new species which are here described and named Ooencyrtus zoeae and Ooencyrtus mevalbelus. These features were combined with reliable morphological characters to facilitate the separation of these species. A dichotomous key and a new synonymy are proposed. Ooencyrtus pistaciae had two distinct COI clades but only one ITS2 clade. Crossbreeding trials that included Ooencyrtus telenomicida, Ooencyrtus melvabelus sp. nov. and Ooencyrtus zoeae sp. nov. confirmed their reproductive isolation. COI sequences showed 0–0.8% and 4–9% within and between-species genetic differences, respectively. ITS2 showed 0.4–5.9% genetic differences between species, with no genetic differences within species. Haplotype diversity of Israeli and Turkish populations of the various species was 0–0.98 and was particularly low in Ooencyrtus pityocampae, whose Israeli population showed no diversity. The discovery of the Ooencyrtus spp. on the eggs of the caper bug, and their abundance support the idea that the bug can be used as an alternative host for augmentation of populations of these parasitoids in agricultural and forestry systems.

Highlights

In recent years molecular tools have been widely applied to facilitate the identification of important biocontrol agents [1] and to separate closely related parasitoid species [2,3,4,5,6]
All species and groups were found in Israel, but only O. zoeae, O. telenomicida and O. pityocampae were found in Turkey
The present study focuses on the Ooencyrtus spp. parasitoid complex occurring in the caper bug (CB) eggs

Summary

Introduction

In recent years molecular tools have been widely applied to facilitate the identification of important biocontrol agents [1] and to separate closely related parasitoid species [2,3,4,5,6]. Ooencyrtus pityocampae Mercet is a well-known egg parasitoid of the pine processionary moth (PPM) Thaumetopoea pityocampae Den and Schiff/T. wilkinsoni Tams species complex (Lepidoptera: Notodontidae), a major defoliator of pine throughout the Mediterranean basin [18,19,20]. In Israel, the eggs of the PPM are found mainly in September through November [32], it was assumed that O. pityocampae population alternated seasonally between these two hosts [30] These data suggested that the CB plays a role in conservation of the O. pityocampae population, and potentially could be used for augmentation of OP populations in order to improve biological control of the PPM [30]. We examined the potential importance and use of this parasitoid guild for biological control, with emphasis on the PPM

Materials and methods

Results

Legs with at least hind coxa partially marked brown

Discussion