Mass releases of parasitic minute polyphagous wasps is a common biological pest control practice across the world. The application can reduce chemical insecticide use and therefore contribute to a more sustainable agriculture. Nearly all frequently used species derive from the genus Trichogramma. These wasps are released on several Million hectares of agricultural production, particularly in maize cultivation. This report is aiming to give an insight into a growing system, where Trichogramma practices are still under development. With regards to the application density, efficacy, applied species and environmental risks of Trichogramma in European ecological fruit cultivation was reviewed. The common application methods are lacking consistent results and pest control efficacy, since orchards differ greatly from the usual grain field cropping system. Three research directions to increase efficiency can be distinguished: new application methods (1); environmental attributes that favour Trichogramma (2) and suitable Trichogramma (mixtures) species (3). Development of equipment, suitable to disperse Trichogramma eggs more equally between rows is needed. A nozzle fan, spraying Trichogramma eggs, seemed to decrease costs and labour force by simultaneously increasing pest control consistency. Flower strips, particularly by containing buckwheat and mustard, can increase the longevity and fecundity of the wasps, leading to a better pest control performance. Local Trichogramma species should be preferred, as they are used to the climatic conditions and contribute to agroecological practices. The risk of mass releases on non-target insect species must be surveyed continuously. No significant effects were found, but off-field emigration does happen and needs to be monitored. The research implies the potential of Trichogramma to be used as an agroecological practice, being able to contribute to insecticide reduction. However, many results still need to be tested under commercial conditions.
Table of Contents
1. Introduction
2. Minute polyphagous wasps as biological pest control
2.1. Biology
2.2. Global perspective
2.3. Application in orchards
3. Discussion
Research Objectives and Themes
This report aims to investigate the effectiveness of minute polyphagous wasps of the genus Trichogramma as a biological pest control measure in European ecological fruit cultivation, evaluating its application range, limitations, and potential risks within an agroecological framework.
- Effectiveness of Trichogramma in orchards compared to grain field systems.
- Development of efficient application methods, including new machinery and distribution techniques.
- Impact of environmental factors, such as flower strips, on wasp longevity and fecundity.
- Assessment of environmental risks and impacts on non-target insect species.
- Potential of Trichogramma to facilitate the reduction of synthetic insecticide use.
Excerpt from the Book
2.3. Application in orchards
The use of polyphagous wasps in orchards is recognised for thirty years (Hassan et al. 1988). In Europe, the most prominent example of biological pest control in orchards is the protection against the Codling Moth (Cydia pomonella) and the Plum Moth (Grapholita funebrana) by T. cacoeciae and T. dendrolimi (Jehle et al. 2014). C. pomonella is considered as one of the main pests in the worldwide fruit growing, dedicated to several fruits, e.g. apple, peach, plum and pear cultivation (Blomefield 1989 in Samara et al. 2008). Research and commercial range of application in Central Europe has been conducted increasingly for 20 years (Zimmermann 2004). Because of upcoming resistances against common control practices, like granulovirus (CpGV) and scab-controlling Sulphur products, a diversification of pest control methods is urgently needed. The interest for commercial alternatives in organic fruit growing is increasing and drawing attention to polyphagous wasps (Kienzle et al. 2012, Jehle et al. 2014).
The application of polyphagous wasps in fruit cultivation is more intense than in crop cultivation. Instead of 100,000 eggs (Wajnberg and Hassan 1994 in Martin and Sauerborn 2013) the rates of wasps released in orchards count several Millions per hectare and application. Methods depend on the size of the orchards. In small-scale orchards, cards, containing more than 1,000 Trichogramma pupae are attached to every or every second or third tree. The wasps are about to emerge shortly after their application. More larvae can be applied in a less developed stage, so several waves of wasps will hatch in the following weeks (Kienzle et al. 2012). The card frequency is determined by the high cost of application, since the costs per hectare and application is estimated to be around 250 to 350 € (AMW, OMYA, Rincon-Vitova, Sautter & Stepper). The research on application methods has therefore increased considerably (Zimmermann 2004). Many trials to increase the efficiency have been implemented. Generally, three different directions of efficiency increase can be pointed out: research on the application method (1), on improving the environmental attributes for Trichogramma (2) and on finding suitable Trichogramma (mixtures) species (3).
Summary of Chapters
1. Introduction: This chapter outlines the role of agroecology in reducing synthetic pesticides and introduces the use of polyphagous wasps as a biological alternative for pest management.
2. Minute polyphagous wasps as biological pest control: This chapter reviews the biological mechanisms of Trichogramma, their global use in agriculture, and specific practices for their application in fruit orchards.
3. Discussion: This chapter synthesizes the challenges of applying Trichogramma in orchards, such as structural issues and climate dependency, and evaluates the potential of this method for commercial agroecological farming.
Keywords
Agroecology, Biological pest control, Trichogramma, Fruit cultivation, Codling Moth, Parasitic wasps, Inundative release, Insecticide reduction, Biodiversity, Non-target effects, Orchards, Sustainable agriculture, Integrated pest management, Biological mechanism, Environmental risk assessment.
Frequently Asked Questions
What is the primary focus of this paper?
The paper focuses on the potential of minute polyphagous wasps, specifically the genus Trichogramma, as a biological pest control method in European ecological fruit cultivation.
What are the central themes discussed?
The central themes include the effectiveness of Trichogramma, application strategies, the impact of environmental factors on wasp performance, and the environmental risks regarding non-target species.
What is the main research question or goal?
The goal is to investigate whether the release of parasitic wasps is a suitable, effective, and environmentally compatible practice for agroecological fruit growing and to what extent it can help reduce synthetic insecticide use.
Which scientific methods are primarily used in this research?
This study is a literature review that synthesizes various scientific research, field trials, and ecological assessments regarding the use of Trichogramma wasps in agriculture.
What topics are covered in the main body of the work?
The main body covers the biology of Trichogramma, their global application perspective, current techniques for orchard application, and a discussion on future development needs and limitations.
Which keywords characterize this work?
Key terms include Agroecology, Biological pest control, Trichogramma, Codling Moth, Inundative release, and Sustainable agriculture.
Why is the application of Trichogramma more intensive in orchards than in standard crops?
The application is more intensive in orchards because of the structural differences of fruit trees and the need to achieve higher population densities of wasps to combat specific pests like the Codling Moth effectively.
What role do flower strips play in the application of these wasps?
Flower strips serve to increase the longevity and fecundity of the wasps by providing essential resources like nectar and pollen, thereby improving the overall pest control performance.
Why does the paper advise against the use of exotic species?
The use of exotic species is considered incompatible with agroecological principles, as it may disrupt local predator/prey balances and poses potential risks of invasiveness.
What is the limitation regarding current orchard application?
Current methods like card release are often too expensive for large-scale operations and exhibit inconsistent pest control results across orchard rows, necessitating the development of better machinery like fan sprayers.
- Arbeit zitieren
- Moritz Stüber (Autor:in), 2018, Minute polyphagous wasps as biological pest control in European ecological fruit cultivation, München, GRIN Verlag, https://www.hausarbeiten.de/document/451381
