Risk assessment of maize damage by wireworms (Coleoptera: Elateridae) as the first step in implementing IPM and in reducing the environmental impact of soil insecticides
Risk assessment of maize damage by wireworms (Coleoptera: Elateridae) as the first step in implementing IPM and in reducing the environmental impact of soil insecticides
L. Furlan 0 1 2
B. Contiero 0 1 2
F. Chiarini 0 1 2
M. Colauzzi 0 1 2
E. Sartori 0 1 2
I. Benvegnù 0 1 2
F. Fracasso 0 1 2
P. Giandon 0 1 2
0 Veneto Agricoltura , Viale dell'Università, 14, 35020 Legnaro, PD , Italy
1 ARPAV Servizio Osservatorio Suolo e Bonifiche , Via S. Barbara, 5/a, 31100 Treviso, TV , Italy
2 Dipartimento di Medicina Animale, Produzioni e Salute-Università degli Studi di Padova , Viale dell'Università, 16, 35020 Legnaro, PD , Italy
A survey of maize fields was conducted in northeast Italy from 1986 to 2014, resulting in a dataset of 1296 records including information on wireworm damage to maize, plant-attacking species, agronomic characteristics, landscape and climate. Three wireworm species, Agriotes brevis Candeze, A. sordidus Illiger and A. ustulatus Schäller, were identified as the dominant pest species in maize fields. Over the 29-year period surveyed, no yield reduction was observed when wireworm plant damage was below 15 % of the stand. A preliminary univariate analysis of risk assessment was applied to identify the main factors influencing the occurrence of damage. A multifactorial model was then applied by using the significant factors identified. This model allowed the research to highlight the strongest factors and to analyse how the main factors together influenced damage risk. The strongest factors were: A. brevis as prevalent damaging species, soil organic matter content >5 %, rotation including meadows and/or Responsible editor: Philippe Garrigues double crops, A. sordidus as prevalent damaging species, and surrounding landscape mainly meadows, uncultivated grass and double crops. The multifactorial model also showed how the simultaneous occurrence of two or more of the aforementioned risk factors can conspicuously increase the risk of wireworm damage to maize crops, while the probability of damage to a field with no-risk factors is always low (<1 %). These results make it possible to draw risk maps to identify low-risk and high-risk areas, a first step in implementing bespoke IPM procedures in an attempt to reduce the impact of soil insecticides significantly.
Agriotes brevis; Agriotes sordidus; Agriotes ustulatus; Wireworms; Maize; Damage risk factors; Multifactorial model; Mutual-fund
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The implementation of integrated pest management (IPM)
strategies against wireworms has been extremely difficult
due to the lack of available information on the key aspects
of the species concerned (Furlan 2005). IPM strategies have
not played a significant role in maize and other arable crops to
date (Furlan and Kreutzweiser 2015) despite the strong
negative impact of using soil insecticides (i.e., neonicotinoids) to
control wireworms (van der Sluijs et al. 2015). EU Directive
2009/128/EC on the sustainable use of pesticides made it
compulsory to implement IPM for all annual crops in
Europe from January 2014. Therefore, accurate information
about IPM strategies for annual crops is urgently needed, but
this information must take into account that arable farming has
few resources in terms of income, labour and technology. In
order to implement IPM at low cost, it is important to establish
the risk factors that cause an increase in wireworm population
levels and the consequent damage. This research aimed to:
find out the main entomological, agronomical and
climatic factors that significantly increase the risk of wireworm
damage;
assess the most probable maize damage level in the
presence of one or more risk factors; and
establish the most effective procedure to implement IPM
of wireworms in maize, considering the major risk factors
that increase wireworm populations.
Materials and methods
An extensive survey of maize fields was conducted in
northeast Italy (area covered: 45.64 °N, 12.96 °E and
45.05 °N, 11.88 °E) from 1986 to 2014 (29 consecutive
years), resulting in a dataset of 1296 records. Each record
includes all the information in Table 1. The fields
surveyed represent a balanced sample of agronomic
conditions in northeast Italy. All the entomological (collection
of larvae, species determination) and agronomic (crop
stand and damage, cultivation practises, yield)
information was directly collected with at least six inspections
per field each year. Just 6 % of the rotation and landscape
data was from farmer interviews (i.e., previous year data
regarding fields reported for the first time and new to the
authors). Data for the other parameters were collected
from official regional databanks (see Soil properties).
The majority of the fields surveyed were untreated (no
soil insecticide or insecticide-coated seeds), except for
those seeded alternately, with untreated and treated maize
in strips/plots (particularly where higher wireworm
densities were recorded with bait trapping method [Furlan
2014]), and those (...truncated)