A Sugarcane Aphid “Super‐Clone” Predominates on Sorghum and Johnsongrass from Four US States

Abstract

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.

Host plant resistance, foliar insecticide application and natural enemies play a role in the management of Melanaphis sorghi (Hemiptera: Aphididae) in grain sorghum

“…Melanaphis sorgi was first detected on the Florida peninsula on the southeastern coast of the United States in 1977 and consequently only achieved a minor pest status in sugarcane production (Denmark, 1988;Mondor et al, 2006). Following the detection of a new haplotype of M. sorghi in Texas and Louisiana in 2013 (Harris-Shultz et al, 2017;Medina et al, 2017;Nibouche et al, 2018), the pest became a significant economic pest of sorghum (Bowling et al, 2016) and has since spread to 25 states in the southern United States, thus infesting all sorghum-production regions (Peterson et al, 2018;EDDMapS, 2020). As of the time, this aphid was originally misidentified as the sugarcane aphid, Melanaphis sacchari, until a recent study (Nibouche et al, 2021) based on morphological and molecular evidence revised its name to M. sorghi.…”

Evaluation of strains of Beauveria bassiana and Isaria fumosorosea to control sugarcane aphids on grain sorghum

“…Gel images were scored visually. The sample Bellflower1 was used as a control for the predominant sugarcane aphid genotype found in the United States since 2013 (Harris‐Shultz et al., 2017; Harris‐Shultz et al., 2018; Nibouche et al., 2018; Paudyal et al., 2019). Bellflower1 was originally collected on sorghum in September of 2015 on Bellflower Farm in Tifton, GA. Colonies that had identical alleles to the Bellflower1 sample were used for the lab bioassay.…”

“…The invasive asexual sugarcane aphid was found to be a “super‐clone” (a predominant genotype that is widespread in space and time) (Vorburger, Lancaster, & Sunnucks, 2003) on sorghum and Johnsongrass [ Sorghum halapense (L.) Pers.] (Harris‐Shultz et al., 2017; Harris‐Shultz, Brewer, Wadl, Ni, & Wang, 2018; Nibouche et al., 2018). Damage to sorghum caused by sugarcane aphid feeding includes leaf pigmentation, leaf chlorosis, leaf necrosis, stunted growth, poor plant vigor, increased water stress, accelerated senescence, delay or prevention of head emergence, and plant death (Brewer, Bowling, Michaud, & Jacobson, 2016; Peterson, Armstrong, Pendleton, Stelter, & Brewer, 2018; Singh, Padmaja, & Seetharama, 2004; Villanueva et al., 2014).…”

Parasitoids and Predators of the Invasive Aphid Melanaphis sorghi Found in Sorghum and Non-Crop Vegetation of the Sorghum Agroecosystem

“…This aphid was not previously considered a significant sorghum pest in North America [ 1 ]. Supported by morphometric and molecular research, the aphid on sorghum and Johnson grass is considered a superclone, distinct from that found on sugarcane [ 2 ]. It was reclassified as Melanaphis sorghi (Theobald) (Hemiptera: Aphididae) with its likely origin in Africa or Asia [ 3 ].…”

“…Specific to the sorghum agroecosystem, seasonal occurrence and composition of non-crop vegetation are attributes that may be relevant to natural enemies suppressing M. sorghi in the protected sorghum crop. For example, Johnson grass, adjacent to sorghum fields in riparian areas and agricultural ditches, may provide green vegetation for M. sorghi [ 2 ] and other aphids that support natural enemy persistence, especially when sorghum is not in cultivation. Sorghum regrowth after grain harvest that persists through mild winters in southern regions may serve the same function (A.M.F., M.J.B.…”