The Efficacy of Seed Treatments on Major Sugar Beet Pests: Possible Consequences of the Recent Neonicotinoid Ban

Abstract

Sugar beet production remains unprotected after the ban on neonicotinoids, while pest pressure is increasing. Although the organic approach to agriculture is highly welcomed, the question remains whether it will be possible to grow sugar beet without pesticides. The aim of this study is to determine the efficacy of seed treatments with neonicotinoids on the main sugar beet pests, to determine the susceptibility of the pests under the specific climatic conditions and to discuss possible consequences of the ban of neonicotinoids on the future of sugar beet production in southeast Europe. The study was conducted in two different climatic regions in Croatia in two consecutive years. The tested variants were: seed coated with imidacloprid, seed coated with a combination of thiamethoxam and teflutrin and untreated control. Our results showed that seed coatings with imidacloprid and thiamethoxam provided satisfactory protection against wireworms, flea beetles and sugar beet weevils at low population pressure. These pests are regular pests of sugar beet in southern and eastern Europe and therefore need to be controlled. Caterpillars and aphids were present in low populations, so the efficacy of the insecticides tested cannot be determined with certainty. A further research program is needed to find alternative solutions and develop easily implementable strategies for all sugar beet pests. We would propose an authorization of neonicotinoids for seed treatment of sugar beet in the regions with high infestation pressure of the main sugar beet pests.

Plant protection consequences in Hungary of the withdrawal of systemic active substances from sugar beet seed treatment

“…Hungarian sugar beet production is currently concentrated mainly in the region of the only sugar factory in operation (Figure 1). Sugar beet requires one of the most intensive technologies among crops grown in Hungary (Radics, 2012), and the withdrawal of pesticide active substances indicate complications of early pest control (Viric Gasparic et al, 2021).…”

“…Differences between arthropod and mammalian nAChRs, particularly in the properties and structure of the subunits, may explain the high selectivity of neonicotinoids for arthropods and their presumed relatively low toxicity in mammals Casida, 2003, 2005). Insecticide spraying was only necessary in cases, where A. punctiventris pressure was high, so neonicotinoid seed treatment contributed to considerable reduction in the amount of insecticides (Bazǒk et al, 2012;Potyondi et al, 2014;Viric Gasparic et al, 2021). This was further enhanced with the emergence of neonicotinoid-treated seeds, such as banding, film coating, pelleting or multi-layer coating, are effective in protecting young plants from insect damage (Altmann, 1991;Meredith and Morris, 2003;Elbert and Nauen, 2004).…”

“…This was further enhanced with the emergence of neonicotinoid-treated seeds, such as banding, film coating, pelleting or multi-layer coating, are effective in protecting young plants from insect damage (Altmann, 1991;Meredith and Morris, 2003;Elbert and Nauen, 2004). Neonicotinoids have been widely used for seed treatment from the 1990s in including sugar beet (Viric Gasparic et al, 2021). Neonicotinoids have a significant advantage over previous soil-based insecticides because they have a wide range of target organisms and are effective for long periods against early spring pests (Figure 3).…”

“…This was done using various organophosphates, carbamates or pyrethroids that were replaced by neonicotinoid seed treatment in recent decades and due to their high efficacy in controlling a wide range of pests and maintaining high yield stability, neonicotinoids became generally used on sugar beet seeds in most European countries (International Confederation of European Beet Growers, 2018). Since neonicotinoids provided adequate protection, in most cases, no further insecticide applications were necessary (Hauer et al, 2017;Viric Gasparic et al, 2021).…”

Suitability of Amaranthaceae and Polygonaceae species as food source for the sugar beet weevil Asproparthenis punctiventris Germar

“…Seed treatments with neonicotinoids used to give satisfactory protection due to their systemic activity during the most sensitive stages of sugar beet plant development, at least in years with low weevil population densities. Lately their use in the field was banned by the European Commission because of their risk to bees (Wechselberger 2020;Viric Gasparic et al 2021). Drmic et al (2017) tested the practicability of mass trapping with a pheromone-based attractant in traps.…”