Sequestration of Defenses against Predators Drives Specialized Host Plant Associations in Preadapted Milkweed Bugs (Heteroptera: Lygaeinae).

AbstractHost plant specialization across herbivorous insects varies dramatically, but while the molecular mechanisms of host plant adaptations are increasingly known, we often lack a comprehensive understanding of the selective forces that favor specialization. The milkweed bugs (Heteroptera: Lygaeinae) are ancestrally associated with plants of the Apocynaceae from which they commonly sequester cardiac glycosides for defense, facilitated by resistant Na+/K+-ATPases and adaptations for transport, storage, and discharge of toxins. Here, we show that three Lygaeinae species independently colonized four novel nonapocynaceous hosts that convergently produce cardiac glycosides. A fourth species shifted to a new source of toxins by tolerating and sequestering alkaloids from meadow saffron (Colchicum autumnale, Colchicaceae). Across three milkweed bug species tested, feeding on seeds containing toxins did not improve growth or speed of development and even impaired growth and development in two species, but sequestration mediated protection of milkweed bugs against two natural predators: lacewing larvae and passerine birds. We conclude that physiological preadaptations and convergent phytochemistry facilitated novel specialized host associations. Since toxic seeds did not improve growth but either impaired growth or, at most, had neutral effects, selection by predators on sequestration of defenses, rather than the exploitation of additional profitable dietary resources, can lead to obligatory specialized host associations in otherwise generalist insects.

Taxonomic review of the genus Rhodostrophia Hbner, 1823 (Geometridae: Sterrhinae) in Iran.

So far, the species of the genus Rhodostrophia Hbner, 1823 (Geometridae), their diagnostic characters and their distribution in Iran have not been investigated in detail. Moreover, some species were misunderstood by earlier authors. To solve these problems, a survey of the Iranian Rhodostrophia species based on over 1700 specimens has been executed. The type series of all species known from Iran were examined. Additionally extensive material from different museums and private collections was morphologically studied and compared with the type material. DNA-barcoding was used as an independent line of information and the results were compared with the morphological data. Examination of the type material revealed that R.cuprinaria (Christoph, 1876) was misinterpreted for a long time. The taxon R.nubifera Brandt, 1941 syn. nov. is a younger synonym of Hugo Christophs R.cuprinaria, which was misidentified by himself in his later publications. An available name for R.cuprinaria in the old, erroneous sense is R.phaenicearia (Hampson, 1907). Three subspecies were recognized for R. terrestraria, including R. terrestraria farsi ssp. nov. Additionally, R. terrestraria furialis Brandt, 1941 syn. nov. is hereregarded as junior synonym ofR. terrestraria(Lederer, 1869); Rhodostrophia nubifera nubifera Brandt, 1941 syn. nov. and R. nubifera klapperichi Wiltshire, 1966 syn. nov. are here regarded as junior synonyms of R. cuprinaria (Christoph, 1876). R. abscisaria chlorotica Wiltshire, 1967 syn. nov. is downgraded to synonymy of R. abscisaria Brandt, 1941 and R. peripheres debilis Wiltshire, 1949 syn. nov. to synonymy of R. peripheres Prout, 1938. Rhodostrophia vahabzadehi sp. nov. is described as a new species. In total, 15 species are regarded as valid for the fauna of Iran. External and internal morphological characters for all examined species are illustrated. Distribution data are shown on maps for of all species. An updated checklist is presented for the Iranian representatives of the genus Rhodostrophia.

Long-term large-scale decline in relative abundances of butterfly and burnet moth species across south-western Germany.

Current studies have shown a severe general decline in insect species diversity, their abundance, and a biomass reduction of flying insects. Most of previous studies have been performed at single sites, or were spatially restricted at the landscape level. In this study, we analyse trends of species richness and shifts in species composition of butterflies and burnet moth species across the federal state of Baden-Württemberg in south-western Germany, covering an area of 35,750 km2. The data set consists of 233,474 records and covers a period from 1750 until today. We grouped species according to their species´ specific functional traits and analyse how species with different habitat requirements and behaviour respond to land-use changes over time. Our data document a significant loss of relative abundance for most species, especially since the 1950s until today. Species demanding specific habitat requirements are more seriously suffering under this trend than generalists. This in particular affects taxa adapted to extensively used xerothermic grasslands, bogs or other habitats maintained by traditional low-productivity agricultural practices of the past. Our data indicate large-scale decline in relative abundance of many butterfly and burnet moth species, which happened in particular during the past few decades.