RESUMO

To determine the factors leading to outbreaks of the sugarcane aphid, Melanaphis sacchari, (Zehntner) (Hemiptera: Aphididae) in sorghum in Haiti, a survey was carried out on farms during two cropping seasons, spring and fall of 2018. A total of 45 plots in three Haitian regions were monitored from the five-leaf stage to grain ripening. Infestation with M. sacchari was significantly higher in spring than in fall, except in one location. Melanaphis sacchari populations varied significantly according to phenological stages of sorghum, with significantly higher abundance during the heading and flowering stages than other stages. In and around sorghum fields, the sugarcane aphid was observed on plants from three families: Poaceae, Malvaceae, and Cucurbitaceae. Aphid natural enemies found in sorghum fields consisted of eight species of ladybeetles (Coleoptera: Coccinellidae), one hoverfly (Diptera: Syrphidae), one lacewing (Neuroptera: Chrysopidae), and one predatory midge (Diptera: Cecidomyiidae). In addition to these predators, two parasitoid species, Adialytus sp. (Hymenoptera: Braconidae) and Pachyneuron aphidis (Bouché) (Hymenoptera: Pteromalidae), emerged from sugarcane aphid mummies. Predator and parasitoid densities were highly affected by growing season, with most of the biological control happening in fall. This study provides insights on sugarcane aphid management in Haiti and the Caribbean Islands.

Assuntos

Afídeos , Saccharum , Sorghum , Animais , Haiti , Especificidade de Hospedeiro , Grão Comestível

RESUMO

Melanaphis sorghi (Hemiptera: Aphididae), are an economically important pest to sorghum in the Americas. Previous studies have found that a super-clone that belongs to multilocus lineage (MLL)-F predominated in the U.S. from 2013 to 2018 and uses multiple hosts besides sorghum. In contrast, previous studies found that aphids in South America belong to MLL-C, but these studies only examined aphids collected from sugarcane. In this study we sought to determine if the superclone persisted in the U.S. in 2019-2020 and to determine the MLL of aphids found on sorghum in the largest country in South America, Brazil. Melanaphis spp. samples (121) were collected from the U.S. in 2019-2020 and Brazil in 2020 and were genotyped with 8-9 Melanaphis spp. microsatellite markers. Genotyping results showed that all samples from the U.S. in 2019 and Brazil in 2020 had alleles identical to the predominant superclone. Of the 52 samples collected in the U.S. in 2020, 50 samples were identical to the predominant super-clone (multilocus lineage-F; M. sorghi), while two samples from Texas differed from the super-clone by a single allele. The results demonstrated that the super-clone remains in the U.S. on sorghum, Johnsongrass, and giant miscanthus and is also present on sorghum within Brazil.