Abstract:Most aphids are highly specialized on one or two related plant species and generalist species often include sympatric populations adapted to different host plants. Our aim was to test the hypothesis of the existence of host specialized lineages of the aphid Melanaphis sacchari in Reunion Island. To this end, we investigated the genetic diversity of the aphid and its association with host plants by analyzing the effect of wild sorghum Sorghum bicolor subsp. verticilliflorum or sugarcane as host plants on the ge… Show more
“…The surprising occurrence of sugarcane aphid on sorghum in 2013 has led to speculation about the source of the aphid, including the possibilities of a host plant shift from sugarcane to sorghum in North America or an existing biotype that prefers sorghum entering North America through wind-aided movement or human activities. The genetic diversity is just beginning to be understood (Nibouche et al 2015), and its capacity for long-range movement can be inferred by field observations and research on other aphids in North America (Irwin and Thresh 1988). Fig.1.Occurrence of sugarcane aphid on sorghum in the United States, 2013.
…”
Section: Occurrence and Damage On Sorghum In The United States And Mementioning
In 2013, the sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), a new invasive pest of sorghum species in North America, was confirmed on sorghum in 4 states and 38 counties in the United States. In 2015, the aphid was reported on sorghum in 17 states and over 400 counties as well as all sorghum-producing regions in Mexico. Ability to overwinter on living annual and perennial hosts in southern sorghum-producing areas and wind-aided movement of alate aphids appear to be the main factors in its impressive geographic spread in North America. Morphological characteristics of the sugarcane aphid include dark tarsi, cornicles, and antennae, allowing easy differentiation from other aphids on the crop. Sugarcane aphid damages sorghum by removing sap and covering plants with honeydew, causing general plant decline and yield loss. Honeydew and sooty mold can disrupt harvesting. The aphid’s high reproductive rate on susceptible sorghum hybrids has resulted in reports of yield loss ranging from 10% to greater than 50%. In response, a combination of research-based data and field observations has supported development of state extension identification, scouting, and treatment guides that aid in initiating insecticide applications to prevent yield losses. Highly efficacious insecticides have been identified and when complemented by weekly scouting and use of thresholds, economic loss by sugarcane aphid can be minimized. Some commercial sorghum hybrids are partially resistant to the aphid, and plant breeders have identified other lines with sugarcane aphid resistance. A very diverse community of predators and parasitoids of sugarcane aphid has been identified, and their value to limit sugarcane aphid population growth is under investigation.
“…The surprising occurrence of sugarcane aphid on sorghum in 2013 has led to speculation about the source of the aphid, including the possibilities of a host plant shift from sugarcane to sorghum in North America or an existing biotype that prefers sorghum entering North America through wind-aided movement or human activities. The genetic diversity is just beginning to be understood (Nibouche et al 2015), and its capacity for long-range movement can be inferred by field observations and research on other aphids in North America (Irwin and Thresh 1988). Fig.1.Occurrence of sugarcane aphid on sorghum in the United States, 2013.
…”
Section: Occurrence and Damage On Sorghum In The United States And Mementioning
In 2013, the sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), a new invasive pest of sorghum species in North America, was confirmed on sorghum in 4 states and 38 counties in the United States. In 2015, the aphid was reported on sorghum in 17 states and over 400 counties as well as all sorghum-producing regions in Mexico. Ability to overwinter on living annual and perennial hosts in southern sorghum-producing areas and wind-aided movement of alate aphids appear to be the main factors in its impressive geographic spread in North America. Morphological characteristics of the sugarcane aphid include dark tarsi, cornicles, and antennae, allowing easy differentiation from other aphids on the crop. Sugarcane aphid damages sorghum by removing sap and covering plants with honeydew, causing general plant decline and yield loss. Honeydew and sooty mold can disrupt harvesting. The aphid’s high reproductive rate on susceptible sorghum hybrids has resulted in reports of yield loss ranging from 10% to greater than 50%. In response, a combination of research-based data and field observations has supported development of state extension identification, scouting, and treatment guides that aid in initiating insecticide applications to prevent yield losses. Highly efficacious insecticides have been identified and when complemented by weekly scouting and use of thresholds, economic loss by sugarcane aphid can be minimized. Some commercial sorghum hybrids are partially resistant to the aphid, and plant breeders have identified other lines with sugarcane aphid resistance. A very diverse community of predators and parasitoids of sugarcane aphid has been identified, and their value to limit sugarcane aphid population growth is under investigation.
“… Position and nature of nucleotide substitutions in M . sacchari COI sequence from this study (haplotype H6), from published data (H1, H2, H3) [ 14 , 28 , 29 ], and from Genbank (H4 = JX051388, JX051389, JX051390; H5 = HQ112185, JX051402). …”
Section: Methodsmentioning
confidence: 99%
“…Similar to numerous other aphid studies, which report aphids exhibiting host plant specialization among their populations [ 10 – 13 ], a recent study has demonstrated the existence of sympatric sorghum and sugarcane biotypes in M . sacchari on Reunion Island (Indian Ocean) [ 14 ]. The occurrence of sympatric biotypes in other areas has been assessed, but not been found [ 9 ].…”
In the United States (US), the sugarcane aphid (SCA) Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae) was introduced in the 1970s, however at that time it was only considered a pest of sugarcane. In 2013, a massive outbreak of M. sacchari occured on sorghum, resulting in significant economic damage to sorghum grown in North America including the US, Mexico, and Puerto Rico. The aim of the present study was to determine if the SCA pest emergence in American sorghum resulted from the introduction of new genotypes. To this end we used microsatellite markers and COI sequencing to compare the genetic diversity of SCA populations collected in the Americas after the 2013 SCA outbreak on sorghum (during 2013–2017) to older samples collected before the pest outbreak (during 2007–2009). Our results show that the SCA outbreak in the Americas and the Caribbean observed since 2013 belong to populations exhibiting low genetic diversity and consisting of a dominant clonal lineage, MLL-F, which colonizes Sorghum spp. and sugarcane. The comparison of MLL-F specimens collected post-2013 with specimens collected in Louisiana in 2007 revealed that both populations are genetically distinct, according to COI sequencing and microsatellite data analyses. Our result suggest that MLL-F is a new invasive genotype introduced into the Americas that has spread rapidly across sorghum growing regions in the US, Mexico, Honduras and the Caribbean. The origin of this introduction is either Africa or Asia, with Asia being the most probable source.
“…], sorghum, and Johnsongrass, the distribution of multilocus lineages was influenced by geography but not host plant (Nibouche et al, 2014). Yet SCA collected on Reunion Island in 2007 to 2013 on sugarcane and wild sorghum have MLGs that were classified as multilocus lineage C that were host specific (Nibouche et al, 2015).…”
Section: Genotyping Of 49 Aphid Samples (Supplementalmentioning
The sugarcane aphid [SCA, Melanaphis sacchari (Zehntner), Hemiptera: Aphididae], is the predominant pest of US‐grown sorghum [Sorghum bicolor (L.) Moench]. A previous study found that a single clone was prevalent on samples collected from sorghum in seven states and one territory of the United States in 2015. We sought to determine if this clone was still prevalent on sorghum grown in 2016 and if this clone is also found on Johnsongrass [S. halepense (L.) Pers.]. Forty‐six SCA samples were collected from primarily sorghum and Johnsongrass from 10 cities in four states, and three aphid samples from different genera (Sipha, Rhopalosiphum, and Acyrthosiphon) were obtained. These aphid samples were genotyped with 43 SCA simple sequence repeat (SSR) markers. The predominant aphid clone found on sorghum in 2015 was again the predominant genotype in the 2016 SCA samples collected from sorghum. This same genotype was also found for the SCA samples collected from Johnsongrass in 2015 and 2016, although two samples differed at a single locus. Mixtures of this predominant genotype with three additional genotypes of SCAs were detected for three samples (excluding the control), indicating that multiple genotypes do exist in the United States but at low levels. This study provides evidence that a SCA “super‐clone” has maintained its dominance on sorghum, and it is using the perennial Johnsongrass as an alternative host.
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