Phytomyptera nigrina (Meigen, 1824) (Pn)

Scaramozzino, Pier Luigi, Loni, Augusto & Lucchi, Andrea, 2017, A review of insect parasitoids associated with Lobesiabotrana (Denis & Schiffermueller, 1775) in Italy. 1. DipteraTachinidae and HymenopteraBraconidae (Lepidoptera, Tortricidae), ZooKeys 647, pp. 67-100 : 75

Phytomyptera nigrina (Meigen, 1824) (Pn) Fig. 2

Phytomyptera nigrina Laccone 1978, Nuzzaci and Triggiani 1982, Luciano et al. 1988, Marchesini and Dalla Montà 1992, 1994, 1998, Coscollá 1997, Colombera et al. 2001, Baur 2005, Marchesini et al. 2006, Bagnoli and Lucchi 2006, Martinez et al. 2006, Cerretti and Tschorsnig 2010, Scaramozzino et al. (in press).

Phytomyptera unicolor Rond.: Del Guercio 1899

Phytomyptera nitidiventris Rond.: Silvestri 1912, Catoni 1914, Leonardi 1925, Boselli 1928, Stellwaag 1928, Thompson 1946

Phytomyptera nitidiventris var. unicolor Rond.: Leonardi 1925

Phytomyptera spp. Moleas 1995, Coscollá 1997

Italian distribution of reared parasitoids.

Apulia: Nuzzaci and Triggiani 1982, Laccone 1978

Campania: Silvestri 1912 (Portici, Nola)

Piedmont: Colombera et al. 2001, Baur 2005

Sardinia: Luciano et al. 1988

Tuscany: Del Guercio 1899, Bagnoli and Lucchi 2006, Scaramozzino et al. (in press)

Umbria: Silvestri 1912 (Bevagna)

Veneto: Marchesini and Dalla Montà 1992, 1994, 1998, Marchesini et al. 2006

Emilia-Romagna: Baur 2005 (Bologna, leg. Campadelli)

Distribution.

North Central and South Europe, Russia North West, Ukraine (Fauna Europaea)

Host range.

Larval endophagous koinobiont parasitoid, Phytomyptera nigrina (see Tab. 3) recurs very often in all researches conducted in Italy on parasitoids of Lobesia botrana .

This insect is associated to 29 species of Lepidoptera : Pterophoridae , Pyralidae , Sesiidae , Yponomeutidae and various genera and species of Tortricidae , included Eupoecilia ambiguella .

Among the Tachinidae living on the vine moths, Pn shows the lowest number of hosts. For more details, see Martinez et al. (2006) and with regard to the hosts reported in Italy see Cerretti and Tschorsnig (2010). As known, Pn larva hatches from an egg placed on the integument of the victim and, once actively penetrated, consumes its internal organs and kills it ( Bagnoli and Lucchi 2006). The existence of the puparium inside the host cocoon tight to the skin of the larva is a distinctive character for the species (Fig. 2F). Though Pn plays an important role in the natural control of Lobesia botrana , especially reducing the summer population ( Bagnoli and Lucchi 2006, Thiery et al. 2006), it was not considered suitable for the control of Paralobesia viteana in the US, because of its relatively low host specificity, the low rate of parasitism reported in nature, and, referring in general to Tachinidae , due to previous experiences of unsuccessful releases ( Martinez et al. 2006).

Ecological role.

Its importance as parasitoid depends on the host generation; indeed, various authors found that the parasitism rates are more generally related to the EGVM antophagous generation on grapevine: in this case they can overcome 25% of parasitism rate, both on grapevine in Apulia ( Laccone 1978) and on Daphne gnidium in Sardinia ( Luciano et al. 1988) (see table 2). In Tuscany, Phytomyptera nigrina (Pn) was mostly found in the vineyards of the medium and lower Arno valley, especially on larvae of the anthophagous generation ( Bagnoli and Lucchi 2006). In the natural reserve of San Rossore (Pisa), during several years of investigation carried out on Daphne gnidium , a single specimen of Pn was obtained from EGVM larvae of the second generation, collected in late July 2014 ( Scaramozzino et al. in press), in contrast to observations carried out on the same host plant by other authors (see Table 3), whereas Actia pilipennis was more frequent in our case.

In Piedmont, Pn reached on the first generation of EGVM and EGBM, in two successive years, significant parasitization rates (17.3 and 6.5%), but it was virtually absent (only two individuals obtained) in the second overwintering generation ( Colombera et al. 2001).

Silvestri (1912) collected Pn from June to mid-October, Nuzzaci and Triggiani (1982) cited it as the more frequent parasitoid on Daphne gnidium in summer, with parasitism rates close to 30%. Laccone (1978) obtained Pn also in the second generation, with significant parasitization rates (from 11.4 to 14.7%). In Veneto, parasitization levels detected for this species were very low in the first generation (0.36 and 0.64%; Marchesini and Dalla Montà 1994), slightly higher, but with a significant 14.6%, in the second generation ( Marchesini et al. 2006).

In France, Thiery et al. (2006) found Pn on the first generation of EGVM; they reported parasitization rates ranging from 5.2 to 41.2%. Pn has not been detected for the moment on EGVM overwintering generation, apart from what has been reported in the work of Colombera et al. (2001).