Taxonomic and Functional Structure of Phytophagous Insect Communities Associated with Grain Amaranth

Abstract

Amaranthus are worldwide attacked mainly by leaf chewers and sucker insects. Stem borers and leaf miners follow in importance, while minor herbivores are leaf rollers, folders, and rasping-sucking insects. The herbivorous community observed on Amaranthus spp. in Argentina was consistent with the information reported worldwide both in guild composition and order proportion. Amaranth plants had a higher number of phytophagous species in their native rather than in its introduced range. Occurrence of insect guilds differed in space and time. The highest density of leaf chewers was observed shortly after the emergence of plants, while higher density of borer and sucker insects coincided with reproductive stages of the crop. The sucking guild was observed mainly at panicles, while the insects within the leaf chewer group were registered in both leaves (92.6%, n = 746 adults) and inflorescences (7.4%). The borer guild was also recorded in stems and inflorescences; however, the density of larvae in stems was about four times as high as the density observed in panicles (n = 137 larvae).

The novel and taxonomically restricted Ah24 gene from grain amaranth (Amaranthus hypochondriacus) has a dual role in development and defense

“…Moreover, a functional characterization of this gene using a transgenic approach in Arabidopsis thaliana and Nicotiana tabacum confirmed its positive role not only in defense against herbivory, but also in vegetative growth regulation. The above traits might contribute to the high tolerance to defoliation (Castrillón-Arbeláez et al, 2012 ; Vargas-Ortiz et al, 2013 ) and chewing insect herbivory (Brenner et al, 2000 ; Niveyro and Salvo, 2014 ) previously reported in grain amaranth. Moreover, the overall results indicate that taxonomically restricted genes, mostly found in plant orders rich in extremophytes, such as the Caryophyllales, can be utilized to engineer stress resistance in commercially important crops, such as rice, corn and wheat, which are less tolerant to adverse environmental conditions.…”

Comunidad de insectos fitófagos y enemigos naturales asociados al cultivo de Amaranthus hypochondriacus L. en la región central de Córdoba (Argentina)

“…Entre los agentes que consumen diferentes órganos de la planta de amaranto se encuentran los insectos. Se han documentado alrededor de 255 especies que afectan el cultivo a nivel mundial (Niveyro, 2015). Los defoliadores constituyen el grupo más numeroso y de mayor riqueza específica (Clarke-Harris et al, 2004).…”

Expression of Resistance in Amaranthus spp. (Caryophyllales: Amaranthaceae): Effects of Selected Accessions on the Behaviour and Biology of the Amaranth Leaf-Webber, Spoladea recurvalis (Lepidoptera: Crambidae)

“…Arthropod pests and diseases present a major challenge to optimum productivity of amaranths in several regions of the world including Africa [ 11 , 12 , 13 , 14 ], Asia [ 15 ] and the Americas [ 7 , 16 , 17 ]. Currently, more than 250 species of insect pests have been reported to feed on amaranth worldwide, with a majority (50%) falling in the category of leaf chewers/defoliators [ 11 , 16 , 17 , 18 ].…”