Flagellar Sensillar Equipment of Two Morphologically Closely Related Aphid Hyperparasitoids (Hymenoptera: Figitidae:Alloxysta)

Abstract

The antennal sensillar equipment in the parasitic wasp family Figitidae was analyzed to date only in few species, despite some are associated with crop pests and can have an economic importance. It is the case of the genus Alloxysta, which includes hyperparasitoids of aphids which can potentially reduce effectiveness of primary pest parasitoids. Here we analyzed, through scanning electron microscopy, the diversity, morphology, and distribution of the antennal sensilla in males and females of Alloxysta consobrina (Zetterstedt) and Alloxysta victrix (Westwood), two species with overall very similar morphology. In both species, antennae are filiform and cylindrical, and flagellum was longer in A. victrix. Eight sensillar types have been recognized: four types of sensilla trichoidea (ST-A, ST-B, ST-C, ST-D), sensilla coeloconica, sensilla placoidea, sensilla campaniformia, and sensilla basiconica. ST-A, ST-B, ST-C, and sensilla placoidea were the most abundant types on the antennae and often increased in number and decreased in size toward the tip of antenna. The two species seem to have several differences in their sensillar equipment, possibly in accordance with the different degree of host range. On the other hand, sexual dimorphism is probably due to the different stimuli that have to be correctly processed. The comparison with the other species of Figitidae studied by far showed, at subfamily-level, that variability in sensillar equipment and phylogeny do not agree. This suggests a complex series of morphological changes during evolution of this group. The taxonomic sample should be thus substantially enlarged to disclose possible trends in sensillar equipment evolution in the family.

Morphological analysis of sensilla on different organs in Pachyneuron aphidis, a hyperparasitoid of Myzus persicae

“…These findings were consistent with those described for other related pteromalid species, including Peridesmia discus and Nasonia vitripennis (Miller, ), Nasonia vitripennis (Wibel et al, ), Pteromalus puparum (Dweck, ; Ying et al, ), Pteromalus cerealellae (Onagbola & Fadamiro, ), Rhopalicus tutela (Pettersson et al, ), and Theocolax elegans (Namikawa & Amornsak, ). Our findings were also similar to other parasitic Hymenoptera, including Spathius agrili (Wang, Yang, & Gould, ), Cotesia sesamiae and Cotesia falvipes (Obonyo et al, ), Encarsia guadeloupae (Zhou, Wu, Niu, & Fu, ), Macrocentrus cingulum (Ahmed, Zhang, Wang, He, & Bai, ), Encarsia sophia (Zhang, Zhang, Luo, & Wang, ), Eriborus applicitus (Lu et al, ), Alloxysta consobrina and Alloxysta victrix (Polidori, Freitascerqueira, Pujadevillar, Oliva, & Ferrersuay, ). It should be noted that different terminologies may have been used to describe the same sensilla in these earlier studies (Table ).…”

Evaluation of three molecular markers for identification of European primary parasitoids of cereal aphids and their hyperparasitoids

“…This is in accordance with findings on the patterns of antennal sensillar equipment of this species, which also suggest the existence of cryptic species in A . victrix [ 69 ]. To conclude, it is possible to use the DNA sequences of both COI and 16S to discriminate species between all non-Aphidiinae investigated here.…”