Feeding of lygaeid bugs (Heteroptera, Lygaeidae) on the common milkweed (Asclepias syriaca L.) in Kaniv Nature Reserve

Abstract

The paper presents data on the feeding of three species of bugs of the Lygaeidae family: Tropidothorax leucopterus (Goeze, 1778), Lygaeus equestris (Linnaeus, 1758) and L. simulans (Deckert, 1985) on common milkweed (Asclepias syriaca L.) in the conditions of Kaniv nature reserve, located in the forest-steppe zone in the central part of Ukraine. Common milkweed is a dangerous invasive species, a transformer of ecosystems, which poses a threat to local plant and animal communities. There is a problem in finding methods of limiting the spread of populations of this species. Among the factors that contribute to its limitation may be the consumption of common milkweed by animals, in particular by phytophagous insects. The study was conducted during the growing seasons of 2022 and 2023 on the grassland area overgrown with tree and shrub vegetation on the hills on the right bank of the Dnipro River. Tropidothorax leucopterus were feeding on sap from the vegetative body of common milkweed plants, being, for the most part, on the lower surface of the leaves. They formed dense groups, and the number of bugs on one plant could reach up to 100 individuals. Both the nymphs (from June to September) and the adults (from August to October) of this species were noted. During the study, it was also observed feeding of this species on the white swallow-wort (Vincetoxicum hirundinaria Medik.), which is a traditional food object for this insect. But only single individuals of these bugs were found on the white swallow-wort. The representatives of the other two species, Lygaeus equestris and L. simulans, fed on the content of the common milkweed seeds during the fruit opening period. Separate individuals or small groups (up to 20 individuals) were observed, adults and single nymphs were noted. The transition of native phytophagous species to feeding on the common milkweed can facilitate its inclusion in food chains in local ecosystems and limit the spread of this aggressive introduced plant species