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The morphology and histology of the male reproductive system of Phyllobius fulvago were described and discussed in relation to other Coleoptera species. The results show that Ph. fulvago has two-lobed flower-shaped arranged testes, each lobe with fourteen follicles. There are two types of glands in the male reproductive system in Ph. fulvago: tubular accessory glands and lobed prostate glands.

In 2003–2004, 102 species of five weevil families were found in the steppe and desert associations of the Caspian semi-desert (Dzhanybek Station). Representatives of Curculionidae predominated (87 species). The majority of the commonest weevil species (20) were most abundant in the steppe associations, only 6 species being found in the desert ones. The composition of the weevil community changed abruptly from spring to summer. The greatest species richness (86 species) was observed in spring; only in this period weevils living mostly on the soil surface had high densities. In the herbage, both in the steppe and desert communities, detritophagous steppe species Archaeophloeus inermis and Trachyphloeus amplithorax were abundant; the habitats of the solonetz complex (on microelevations and in the depressions), the desert-steppe and steppe species (Humeromima nitida, Mesagroicus poriventris, Temnorhinus strabus) associated with saline substrates were also present. The spring hortobiont assemblage was dominated by the polyphagous steppe weevils, Euidosomus acuminatus, Phyllobius brevis and Omias spp. In summer, 53 species of weevils were recorded; their numbers on the soil surface sharply dropped, the core of the herbage assemblage consisted of the weevils feeding on alfalfa (Stenopterapion tenue, Sitona spp., Tychius spp.) in the steppe associations, with the maximum abundance in the more humid depressions. The summer assemblage of the desert herbage was poor and consisted of the species associated with wormwoods and chenopods (Ptochus porcellus, Phacephorus argyrostomus, Metadonus anceps). The autumn groupings with only 24 species were poor and had low population densities.

In desert and steppe habitats of the complex North Caspian semi-desert, more than twofold differences in the number of hortobiont Curculionoidea species (33 and 75 species, respectively) were observed between the “dry” (1972–1974) and “humid” (2003–2005) climatic phases. The abundance of most species changed. Polyphagous steppe weevils of the subfamily Entiminae (Otiorhynchus velutinus, Euidosomus acuminatus, Omias verruca, and O. rotundatus) with spring activity of adults were the most stable, representing the main dominants of the spring communities both in the 1970s and 2000s. Nearly all of the weevils that changed their abundance since the 1970s were specialized herbivores with summer adult activity. In the more humid 2000s, the abundance of some desert-steppe weevils dominating the desert communities (Phacephorus nebulosus, Metadonus anceps and especially Ptochus porcellus) dropped drastically. Most of the species whose abundance increased most strongly (Phyllobius brevis, Trachyphloeus amplithorax, Archaeophloeus inermis, Stenopterapion tenue, Sitona inops, S. longulus, Tychius spp.) are associated with Medicago romanica, the plant that considerably raised its density in the microdepressions during the “humid” phase. The data show an evident reduction of the most xerophilic (desertsteppe) components of the weevil community and an increase in the fraction of mesophilic species. These changes seem to follow a cyclic pattern.