• Both pymetrozine and flonicamide are systemic insecticides that are generally used to control aphids. However, these insecticides do not affect mealybugs that are still alive and excrete contaminated honeydew.
• Integrated pest management (IPM) is based on the application of a combination of agronomic, biological and biotechnological measures that minimizes the use of pesticides
A study by the Centre for Research on Desertification (CIDE), a joint center of the Spanish National Research Council (CSIC), the Generalitat Valenciana and the University of Valencia; the Valencian Institute of Agricultural Research (IVIA) and the University of Valencia shows that pymetrozine and flonicamide, two insecticides recommended in some integrated pest management (IPM) programs, can negatively affect biological control agents when they are fed on molasses. The work is applicable to citrus and has been published in the journal Environmental Pollution. Scientists from Wageningen University (The Netherlands) have also participated in the study.
Integrated pest management (IPM) is based on the application of a combination of agronomic, biological and biotechnological measures that minimize the use of pesticides. When pests exceed treatment thresholds and pesticides have to be used, they need to be effective and respectful of biological control agents. The study of pesticide side effects is therefore key in the development of IPM programs, especially in crops such as citrus, where most pests are regulated by biological control agents.
In this regard, it should be noted that both pymetrozine and flonicamide are systemic insecticides that are generally used for aphid control. However, these insecticides do not affect mealybugs that are still alive and excrete contaminated honeydew.
“The study showed that pymetrozine- and flonicamide-contaminated molasses increased mortality of the syrphid Sphaerophoria rueppellii by 20 and 50%, respectively. However, these molasses were harmless to the parasitoid Anagyrus vladimiri (formerly known as Anagyrus pseudococci), one of the main biological control agents of the pseudococcus citri,” says Joel González Cabrera, Ramón y Cajal researcher at the University Institute of Biotechnology and Biomedicine (BIOTECMED) of the University of Valencia.
Daniele Sadutto, researcher at CIDE, and Yolanda Picó, researcher at CIDE and professor at the Department of Preventive Medicine and Public Health of the UV School of Pharmacy, have also participated in the study. According to the latter, “the results of the study indicate that contaminated honeydew is likely to affect a much wider range of beneficial insects than contaminated nectar and should therefore be included in future environmental risk assessments”.
The study, partially funded by a project of the Instituto Nacional de Investigación y Tecnologia Agraria i Alimentaria (INIA, RTA2017-00095), demonstrates the need for further research on the negative effects of insecticides on beneficial insects and the different routes of exposure.
Calvo-Agudo, M., González-Cabrera, J., Sadutto, D., Picó, Y., Urbaneja, A., Dicke, M., & Tena, A. (2020). «IPM-recommended insecticides harm beneficial insects through contaminated honeydew». Environmental Pollution, 115581.
Link: https://doi.org/10.1016/j.envpol.2020.115581 (open access)
CIDE Communication
