Ooctonus vulgatus(Hymenoptera, Mymaridae), a potential biocontrol agent to reduce populations ofPhilaenus spumarius(Hemiptera, Aphrophoridae) the main vector ofXylella fastidiosain Europe

Abstract

As a vector of Xylella fastidiosa (Wells, 1987) in Europe, the meadow spittlebug Philaenus spumarius (Linnaeus, 1758) (Hemiptera, Aphrophoridae) is a species of major concern. Therefore, tools and agents to control this ubiquitous insect that develops and feeds on hundreds of plant species are wanted. We conducted a field survey of P. spumarius eggs in Corsica and provide a first report of Ooctonus vulgatus Haliday, 1833 (Hymenoptera, Mymaridae) as a potential biocontrol agent of P. spumarius in Europe. To allow species identification, we summarized the main characters distinguishing O. vulgatus from other European species of Ooctonus and generated COI DNA barcodes. Parasitism rates were variable in the four localities included in the survey but could reach 69% (for an average number of eggs that hatched per locality of 109). Based on the geographic occurrences of O. vulgatus obtained from the literature, we calibrated an ecological niche model to assess its potential distribution in the Holarctic. Obviously, several questions need to be addressed to determine whether O. vulgatus could become an effective biocontrol agent of P. spumarius in Europe. So far, O. vulgatus has been reared only from P. spumarius eggs, but its exact host-range should be evaluated to ensure efficiency and avoid non-target effect. The top-down impact of the parasitoid on vector populations should also be assessed on large data sets. Finally, the feasibility of mass rearing should be tested. We hope this report serves as a starting point to initiate research on this parasitoid wasp to assess whether it could contribute to reduce the spread and impact of X. fastidiosa in Europe.

Biology and Prevalence in Northern Italy of Verrallia aucta (Diptera, Pipunculidae), a Parasitoid of Philaenus spumarius (Hemiptera, Aphrophoridae), the Main Vector of Xylella fastidiosa in Europe

“…Following the discovery of X. fastidiosa in Europe, namely of the subsp. pauca transmitted to olive by P. spumarius, interest in biological control agents of this pest has greatly increased and has prompted research on natural enemies, namely an egg parasitoid, O. vulgatus [20] and a generalist predator, Z. renardii [21]. Verrallia aucta does not rapidly kill the host, which can survive until late in the season.…”

“…Once the factors favoring the multiplication of this pipunculid under natural conditions are known, an inoculative biological control approach could be envisaged in areas where V. aucta is absent or poorly represented, by transferring parasitized adults into new sites and preserving suitable environmental conditions for its establishment and multiplication. The same should be done with the oophagous parasitoid O. vulgatus, which was found to be common and abundant in the Corsica island of France [20].…”

“…Indeed, it is restricted to reports on the presence of egg parasitoids of the genus Ooctonus (Hymenoptera Mymaridae) and Centrodora (Hymenoptera Aphelinidae), the endoparasitoid Verrallia aucta Fallén (Diptera Pipunculidae) and few uncharacterized entomopathogenic fungi (revised in [8,14]). Interestingly, very recently, one of the oophagous parasitoids recorded from US, Ooctonus vulgatus Haliday, has been found commonly and locally abundant in Corsica island of France [20]. Finally, the newly introduced predatory bug Zelus renardii Kolenati (Hemiptera, Reduviidae) has been proposed for the inundative control of P. spumarius with the aim of suppressing the spread of X. fastidiosa in olive groves of Apulia [21].…”

Populations and Host/Non-Host Plants of Spittlebugs Nymphs in Olive Orchards from Northeastern Portugal

“…The suppression of ground-cover—weeds and shrubs—could have some disadvantages such as: (i) hampering natural enemies by reducing other important resources (such as oviposition and overwintering places or alternative food resources, including pollen and nectar) for natural enemies of both vectors and other pests [ 30 , 31 ]; and (ii) damaging biological, chemical, and physical conditions of soils including fertility and nutrient storage, water storage, soil structure, and erosion [ 32 , 33 ]. In addition, natural enemies may have an impact on the control of vectors of X. fastidiosa , although these are little studied in Europe [ 48 , 49 , 50 ]. Among these, egg parasitoids may represent an important means of vector control.…”

“…Among these, egg parasitoids may represent an important means of vector control. Several egg parasitoids (such as Ooctonus vulgatus Haliday (1833), Gonatocerus sp.—family Mymaridae, Oligosita sp.—family Trichogrammatidae) of X. fastidiosa vectors/potential vectors are described [ 3 , 50 ], and in the northeast of Portugal some preliminary results indicate the existence of egg parasitoids of X. fastidiosa vectors/potential vectors [ 51 ]. Therefore, an excessively early removal of the ground vegetation might damage this parasitoid population by eliminating the parasitized eggs before the parasitoids hatch.…”