Searching for Xylella fastidiosa solutions: survey natural enemies of Auchenorryncha eggs
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The dangerous phytopathogenic bacteria Xylella fastidiosa (Wells et al., 1987)
has been recently detected in Portugal (January 2019). This disease is transmitted
horizontally from infected to non-infected plants by xylem-feeders that belong to the
suborder Auchenorrhyncha. The information available until now about natural enemies is
reduced. In this work the potential natural enemies of Auchenorrhyncha eggs, the most
susceptible stage, were studied during the autumn/winter of 2018/2019. For that, from
November 2018 to February 2019 before the egg hatching, on a biweekly basis, 10 samples
of 50 g of rests of the remaining vegetation in the ground cover, mainly Poaceae, were
collected in an olive grove. In the laboratory, leaves, particularly the interior part of the
blade which is a common oviposition location for spittlebugs, were observed under
binocular stereoscope. Viable eggs were introduced in petri dishes until hatching. A total
of 647 egg-laying masses and 8,222 eggs with a mean of 12.7 eggs per egg laying was
recorded. Egg masses were characterised and the action of predation, parasitism and fungi
were recorded. Eggs presenting signs of parasitism plus predation were more than 50%.
Intact field eggs were kept in controlled conditions until hatching of nymphs and evolution.
The parasitoids were identified as Paracentrobia sp. (Trichogrammatidae) being the first
report for the genus in Portugal. These results constitute an important opportunity to
control the main insect vectors of X. fastidiosa and containing its spread.
