Analysis of cuticular hydrocarbons in two Anagrus species (Hymenoptera: Mymaridae) as a tool to improve their correct identification

Abstract

Male and female adult wasps belonging to the atomus group of the genus Anagrus Haliday, classified according to morphological techniques, were analyzed for their cuticular hydrocarbons to detect any possible differences between species. Most female specimens that were identified as either A. atomus L. or A. ustulatus Haliday, using morphological and morphometrical characters, showed two distinct cuticular hydrocarbon profiles. These profiles seemed to be independent of the plants the insects were collected from, the potential leafhopper host species (Hemiptera: Cicadellidae), and the emergence period, and they were largely consistent with classification based on morphology. Both A. atomus and A. ustulatus females were shown to emerge from leafhopper eggs found on Vitis vinifera L. (Vitaceae). Males, for which conclusive diagnostic characters are not yet available, showed the same two cuticular hydrocarbon patterns observed in females; on average, specimens displaying one hydrocarbon profile differed from those showing the other profile in three characters used for morphometrical analysis.

Autumnal emergence of Anagrus wasps, egg parasitoids of Empoasca vitis, from grapevine leaves and their migration towards brambles

“…‘ atomus ’ group parasitoids, as previously reported (Picotti & Pavan, 1993; Pavan et al , 1997a, b). This occurrence involved both A. atomus and A. ustulatus , according to Floreani et al (2006).…”

“…egg‐laying is supported by the fact that concomitant with the period of the greatest Anagrus captures: (i) developed eggs were observed in the ovaries of these leafhoppers (Filippetto, 2010) and (ii) these leafhoppers must have already laid most of the overwintering eggs during October/November because, in December, after the occurrence of the first severe frosts, captures on traps were scarce and only a few adults were observed on leaves (data not reported). Moreover, the emergence of Anagrus parasitoids from bramble leaves in late winter (Viggiani et al , 2003b; Floreani et al , 2006) can occur only if leafhopper eggs are available on brambles in autumn at the same time as the last season flight of Anagrus spp.…”

“…Concerning the second point, it is known that both A. atomus and A. ustulatus can emerge in spring from bramble leaves (Viggiani et al , 2002, 2006; Floreani et al , 2006; Zanolli, 2010). Chiappini (1987) showed that the eggs of E. rosae are associated with A. ustulatus on garden roses.…”

“…As a result of recent morphological research, however, any habitat management hypothesis needs to consider that A. atomus is a group of at least two species: A. atomus and A. ustulatus . Even though E. vitis would appear to be parasitized only by A. atomus in Northern Italy (Chiappini, 1987; Pavan & Picotti, 2009), A. ustulatus can emerge from grapevine leaves at the same time (Viggiani et al , 2003a; Floreani et al , 2006). Both species can also emerge from Rubus spp.…”

“…Both species can also emerge from Rubus spp. leaves (Viggiani et al , 2003b; Floreani et al , 2006). Moreover, it is necessary to consider that, during the vegetative season, the leafhopper Zygina rhamni Ferrari can also be a host for Anagrus spp.…”