engleski

The effectiveness of the entomopathogenic nematodes Heterorhabditis bacteriophora Poinar 1976 on sugar beet weevil (Bothynoderes punctiventris Germar.) larvae

Leaf area of sugar beet plants in time of insecticides application for sugar beet weevil control (Bothynoderes punctiventris Germar.) is very small (BBCH scale 9-12). Due to the specific morphology and large feeding capacity of the B. punctiventris, insecticide applications often give very poor results. Thus repeated treatments are often required. This is not in accordance with the principles of integrated pest management (IPM) nor with rational use of plant protection measures, to which modern agriculture aims. Therefore, it is necessary to consider non- pesticide plant protection measures and to develop a strategy to control sugar beet weevil. The strategy shall include all available methods that are compatible with all agricultural practices, such as crop rotation, the proper choice of fields, early sowing, sowing of the edges of a field in high-density areas and measures that contribute to rapid plant development. As a part of this strategy bio- insecticides which include entomopathogenic nematodes (EPNs) shall be considered. The aim of this research was to determine the effectiveness of the entomopathogenic nematode Heterorhabditis bacteriophora Poinar 1976 on sugar beet weevil larvae and to assess the potential of this biological insecticide for use in practice. In a two-year study (2014-2015) we conducted field experiments in which the efficacy of three doses of nematodes (product Nematop based on H. bacteriophora): three, five and seven million nematodes/10 m2 has been compared with an untreated control. During the vegetation season number of larvae has been checked regularly, every 2 weeks up to the harvest of sugar beet. Due to the unfavorable climatic conditions in 2014, the number of larvae on untreated check was very low. In 2015, larval population was much higher. The total number of larvae found on nematode treatments in both years was significantly lower comparing to untreated control. In the conditions of weak attack product Nematop in a dose of 7 million/ 10 m2 resulted in an efficacy of 100 %, while the lowest dose of 3 million/ 10m2 achieved efficacy of 78 %. In the conditions of moderate attack the lowest dose did not show any efficacy while the highest dose achieved an efficacy of 93 %. The dose response has been established in both years. The slope of the regression line depends on the attack intensity. It can be concluded that EPN product based on H. bacteriophora has potential to reduce sugar beet weevil larval population and shall be incorporated into the strategy for sugar beet weevil control in endangered areas.

biological insecticides ; entomopathogenic nematodes ; sugar beet weevil

nije evidentirano