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- Title
Impact of Chemical Insecticide Application on Beneficial Insects in Maize.
- Authors
Camerini, Giuseppe; Maini, Stefano; Limonta, Lidia
- Abstract
Simple Summary: In the Po Valley, the control of maize from insect pests (Ostrinia nubilalis and Diabrotica virgifera virgifera) can include insecticide applications. The results of research on insecticide spray's impact on beneficial insects, which can contribute to the biological control of maize pest, are reported. Aphid predators and Trichogramma brassicae (O. nubilalis egg parasitoid) were used as indicators. Chemical insecticide application significantly increased aphid abundance when no rotation protocol was applied. In addition, an alteration in aphid predator community composition was recorded. In insecticide-sprayed fields managed according to repeated crop protocols, the predator community was dominated by hoverflies, while in maize fields where crop rotation was practiced, ladybirds and Orius spp. predominated. In addition, the insecticides had a negative effect on the natural parasitism of T. brassicae. The research suggests that Integrated Pest Management strategies should be planned based on crop rotation protocols and biological control of maize pests. The European corn borer (ECB) (Ostrinia nubilalis Hübner) and to a lesser extent the western corn rootworm (Diabrotica virgifera virgifera LeConte) are a threat to maize in the Po Valley (Northern Italy), and their control can require insecticide applications. The results of a study to evaluate the effects of insecticide sprays on the beneficial insect Trichogramma brassicae (Hymenoptera: Trichogrammatidae) and aphid predators are reported. A three-year research project was carried out in two Study Areas, in Lombardy. In area 1, crop rotation was a common practice, while in area 2 repeated maize crop was practiced. The natural trend of ECB egg masses attacked by T. brassicae was affected and parasitism rates were reduced as a result of insecticide exposure (chlorpyriphos methyl, cypermethrin, alphacypermethrine). Repeated maize crop and insecticides spraying increased the abundance of the aphid population and negatively affected the aphid predator community, which mainly included ladybirds, hoverflies, true bugs and lacewings. The predator community was dominated by hoverflies in sprayed fields managed according to repeated maize crop protocols, whereas ladybirds and Orius spp. dominated in maize fields managed according to crop rotation protocols. Crop rotation protocols help to prevent ECB outbreaks; when the risk of exceeding the economic threshold limit is high, and this may be the case when maize is cultivated for seeds or for horticultural crops such as sweet corn, inundative release of T. brassicae and/or microbial control (i.e., use of Bacillus thuringiensis preparations) can integrate natural biocontrol, and provide a valuable alternative to chemical insecticides.
- Subjects
LOMBARDY (Italy); ITALY; EUROPEAN Central Bank; INSECTICIDE application; INSECTICIDES; SWEET corn; CYPERMETHRIN; CORN; EUROPEAN corn borer; HEMIPTERA; INSECT pests; HORTICULTURAL crops
- Publication
Insects (2075-4450), 2024, Vol 15, Issue 4, p224
- ISSN
2075-4450
- Publication type
Article
- DOI
10.3390/insects15040224