The effectiveness of Chrysoperla carnea (Neuroptera: Chrysopidae) and Beauveria bassiana (Ascomycota: Hypocreales) as control agents of Neophilaenus campestris (Hemiptera: Aphrophoridae) a vector of Xylella fastidiosa

Abstract

The effectiveness of two biological control agents, Chrysoperla carnea (Neuroptera: Chrysopidae) and the entomopatho­genic fungus Beauveria bassiana (Ascomycota: Hypocreales) against nymphs and adults of Neophilaenus campestris (Hemi­ptera: Aphrophoridae) was determined under laboratory conditions. First, different nymphal stages of N. campestris were presented to different larval stages of C. carnea. Second, the effect of the foam produced by N. campestris nymphs on the larvae of C. carnea predation was evaluated. Finally, four concentrations of a wild strain of B. bassiana, BbGEp1, were sprayed on plants in order to determine their lethality for adults of N. campestris. Second and 3rd-instar larvae of green lacewing larvae are capable of capturing and killing 3rd and 5th-instar nymphs of N. campestris. The percentage of 3rd-instar lacewing larvae that killed nymphs was significantly higher than that were killed by second-instar larvae. Second-instar larvae killed significantly more 3rd-instar nymphs than 5th-instar nymphs. Third instar lacewing larvae killed an average (± SEM) of 1.50 ± 0.31 5th-instar nymphs and 2nd-instar larvae killed very few nymphs. Spittlebug foam reduced, but did not prevent predation. The lethality of the entomopathogenic B. bassiana BbGEp1 used against adults of N. campestris was characterized by an LC50 value of 1.61 × 106 conidia/mL and LT50 of 3.63 days at 1 × 107 conidia/mL. The present study provides new and valuable data on the activity of two promising biological control agents of vectors of the bacterium Xylella fastidiosa. Further research is needed to confirm the results presented here and on the cost effectiveness of using these control agents as alternatives to synthetic insecticides for preventing the further spread of X. fastidiosa in Europe.

Keywords

• predation
• natural enemies
• biological control
• entomopathogenic fungus
• bacterium
• median lethal concentration
• transmission
• spittlebug foam