SYNERGISM OF A MIXTURE OF PHOSPHINE AND CARBON DIOXIDE DURING FUMIGATION AGAINST PESTS OF GRAIN STOCKS

Abstract

The work is devoted to the search for alternatives to methyl bromide – a universal fumigant, which was restricted in use at the request of the Montreal Protocol. The article presents the results of the toxic action of mixtures of phosphine gases with carbon dioxide against storage mites and insect pests. Purpose: to establish the synergism of a mixture of phosphine and carbon dioxide in different concentrations by means of fumigation against pests of grain stocks (Coleoptera: genus Sitophilus; Lepidoptera: genus Ephestia; storage mites genus Acarus and Tyrophagus). Methods. Objects of research. Insect pests of the genus Sitophilus and Ephestia; storage mites of the genus Acarus and Tyrophagus. The research material is the preparative form of phosphine “Magtoxin” (tablet form) produced by Detia Degesch GmbH, carbon dioxide in cylinders. Methods: analytical review of the research topics of domestic and foreign scientists, the current regulatory framework in the field of fumigation; analysis of biological characteristics of insect pests and storage mites; experimental – variation of different concentrations of phosphine to establish the synergism of the fumigant with carbon dioxide in laboratory conditions with appropriate equipment; mathematical and statistical – with the help of computer mathematical functions built into the Microsoft Excel 2003 program. The results. The optimal concentrations of phosphine against insect pests, at which, both its synergism with carbon dioxide and high efficiency were noted at the same time, are concentrations in the range of 0.84–0.91 g/m3, at which the mortality of Ephestia kuehniella larvae amounted to levels – 93.4±4.03%, and synergism – 8.9%. When gas mixtures with a phosphine concentration of 1.20–1.21 g/m3 were used against storage mites of the genus Acarus and Tyrophagus, their significant mortality at the level of 95.4±3.35% was observed. However, under the action of phosphine without carbon dioxide in similar concentrations, the mortality of storage mites was also high – 94.7%. Thus, gas synergism was noted only at the level of 0.7%. Conclusions. Unlike storage mites, when using phosphine with carbon dioxide against insect pests at the same time, both the synergism of the gases and their effectiveness were noted. The obtained results indicate the need for further research, in particular the study of the influence of the duration of exposure to fumigation and temperature, which can significantly affect the gas synergism indicator.