In-season leaf damage by a biocontrol agent explains reproductive output of an invasive plant species

By

Augustinus, Benno Andreas
Lommen, Suzanne
Fogliatto, Silvia
Vidotto, Francesco
Smith, Tessa R
Horvath, David
Bonini, Maira
Gentili, Rodolfo
Citterio, Sandra
Müller-Schärer, Heinz
Schaffner, Urs

Type

Article

Date of Publication

2020

Original Publication

NeoBiota : advancing research on alien species and biological invasions

Volume

55

Pages

117--146

Subjects

Ambrosia artemisiifolia , Biological invasions , classical biological control , Common ragweed , herbivory , Ophraella communa

Contributed by

Pensoft Publishers

Language

English

Published by

Sophia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/neobiota.55.46874

 

Abstract

One of the biggest challenges in classical biological control of invasive weeds is predicting the likelihood of success. Ambrosia artemisiifolia, a North American plant species that has become invasive in Europe, causes economic losses due to health problems resulting from its huge amount of highly allergenic pollen and as a weed to agricultural crops resulting from high seed densities. Here we assessed whether the pollen and seed output of the annual A. artemisiifolia (at the end of the season) is related to in-season abundance of, or damage by, the accidentally introduced biological control agent Ophraella communa. We monitored the growth and leaf damage of individually labelled A. artemisiifolia plants at four locations in Northern Italy and recorded abundance of different O. communa life stages at regular intervals. We found that the in-season level of leaf damage by O. communa consistently helped to explain seed production in combination with plant volume and site throughout the season. Feeding damage, plant volume and site also explained pollen production by A. artemisiifolia six weeks before male flower formation. At three out of four sites, plants with more than 10% leaf damage in mid-June or early July had a very low likelihood of seed formation. Leaf damage proved to be a better explanatory variable than O. communa abundance. Our results suggest that the monitoring of the in-season leaf damage can help to project the local impact of O. communa on A. artemisiifolia at the end of the season and thus inform management regarding the needs for additional measures to control this prominent invader.