Ecological Aspects of Seasonal Dynamics of Wheat Thrips and Trophic Relationships in Wheat Agrocenoses

Abstract

Wheat thrips (Haplothrips tritici Kurd.) are the most abundant phytophage in agrocenoses of winter and spring wheat. Small size and life hidden way at development all stages are the reasons for insufficient knowledge of its ecological features. The research aim is to reveal the ecological aspects of wheat thrips seasonal dynamics and trophic relationships in wheat agrocenoses. The research objectives included—to determine the wheat thrips populations composition, structure, and seasonal dynamics—to study food connections and relationships of the phytophage with fodder plants—to analyze the wheat thrips ecology and harmfulness peculiarities in wheat agrocenoses. The studies carried out are devoted to detailed conjugate analysis of the forage plants and wheat thrips population’s development, adults and larvae food connections, and their ecological niche. Data were obtained on seasonal dynamics of the thrips population’s age spectrum number, wintering, its larvae metamorphosis, and harmfulness in the Middle Volga region conditions. The pest adults maximum number reached 2840 pcs/100 strokes of a butterfly net in crops of winter wheat and 15,023 pcs/100 strokes in crops of spring wheat. The adult thrips number peak on winter wheat coincides with the organogenesis IX stage (the flowering phase), on spring wheat with the organogenesis VIII stage (the heading phase). The age composition of the pest population changed according to the wheat development phases, and a large number was noted in winter wheat agrocenoses and amounted to 19.1–20.5 thousand pcs/m2, while in spring agrocenoses—15.0–18.3 thousand pcs/m2.