Melanaphis sacchari & Melanaphis sorghi

Identification & Distribution

Melanaphis sacchari was first described by Zehntner (1897) on sugarcane in Java, and Melanaphis sorghi by Theobald (1904) on sorghum in Sudan. Since then, these two species have commonly been treated as synonyms, and referred to as the ‘sugarcane aphid’, despite evidence to the contrary. Nibouche et al. (2021) have now presented convincing molecular evidence of the existence of two species which are quite readily distinguishable (see below). The first picture below appears to be Melanaphis sacchari, but most of the other pictures on this page are more likely to Melanaphis sorghi.

Image above copyright A. Franck in Nibouche et al. (2018) under Creative Commons CC0 licence.

We first consider distinguishing members of the species group from other Melanaphis species:

Adult apterae of Melanaphis sacchari sp. grp. (see pictures above and below) are broadly spindle-shaped. Their colour varies from pale yellow to yellow brown, dark brown, purple, or even pinkish, depending on host plant and environmental conditions. There is usually a variably developed black dorsal patch. Both the antennal and median frontal tubercles are weakly developed (cf. Melanaphis indosacchari, which has both the antennal and median frontal tubercles rather well developed). The antennal terminal process is 1.9-2.5 times the length of the cauda (cf. Melanaphis indosacchari, which has the terminal process 2.6-3.5 times the length of the cauda). The hairs on antennal segment III are very short being only 0.3-0.5 times the basal diameter of segment III. Abdominal tergites I-IV each have 1-2 hairs on each side and abdominal tergite VIII has 2 hairs. The longest hairs on the hind tibia are not more than 1.2 times the diameter of tibia at midlength. The siphunculi are dark, short and usually thick or rather thick, 0.70-1.05 times the length of the cauda, and usually with a well-developed, rather swollen flange. The cauda is dusky and short, less than 0.1 times the body length (cf. Sitobion miscanthi & Hysteroneura setariae, both of which have a fairly long pale cauda, greater than 0.14 times the body length). The body length of adult apterae is 1.1-2.0 mm.

First image above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka
Second image copyright Katherine Parys under a CC BY-NC 3.0 license.

Both Melanaphis sacchari and Melanaphis sorghi live in ant-attended colonies on cereals and grasses (Poaceae). Melanaphis sacchari is found especially on sugar (Saccharum), but also on cereals such as rice (Oryza) and sorghum (Sorghum) and some Araceae. Melanaphis sorghi is mainly found on sorghum, but is also found on other grasses and cereals. In most places populations are anholocyclic, but in China Melanaphis sacchari sp. grp. is monoecious holocyclic (with alate males) with Miscanthus sacchariflorus (Poaceae) as the overwintering host. Nibouche et al., 2021 found both members of the species group distributed throughout the tropical and subtropical regions. So far Melanaphis sorghi is the sole detected of these in West and in Southern Africa. In East Africa, Melanaphis sacchari has been detected in Kenya and Tanzania, and Melanaphis sorghi in Uganda and Kenya. The islands of Reunion and Mauritius in the Indian Ocean are exclusively colonized by Melanaphis sacchari. The Nearctic zone is colonized by both species, as a result of the recent introduction of Melanaphis sorghi in the Americas. In the Neotropical zone, Melanaphis sacchari was the only species observed before 2016, but studies indicate that Melanaphis sorghi is now present in Brazil. In Asia, Melanaphis sorghi is present in China and India, and Melanaphis sacchari in Cambodia. In Australia and in Hawaii, only Melanaphis sacchari has been detected.  

Biology & Ecology

Natural enemies

Jaimes-Orduña et al. (2020) identified predatory and parasitoid insect species associated with Melanaphis sacchari (and/or Melanaphis sorghi) in Nuevo León, Mexico, and examined their impact on its biocontrol. A total of 8 coccinellid species, 2 syrphid species, and 1 chrysopid species were identified. In addition, 2 hymenopteran parasitoids were found. They were found to have a significant impact on the numbers of this pest.

The images below show predators and parasitoids attacking sugarcane aphids in Texas, USA. The first shows a coccinellid larva, most likely in the Scymnus genus.

Image copyright Patrick Porter, Bugwood.org under a CC BY-NC 3.0 license.

The second (see picture below) shows a syrphid larva predating sugarcane aphids.

Image copyright Patrick Porter, Bugwood.org under a CC BY-NC 3.0 license.

The image below shows a colony of sugarcane aphids with two black mummified aphids. These were parasitized by either an Aphelinus species or an Ephedrus species, both of which produce black mummies.

Image copyright Patrick Porter, Bugwood.org under a CC BY-NC 3.0 license.

Other aphids on the same host

Blackman & Eastop list 20 species of aphid as feeding on sugarcane (Saccharum officinarum) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

Blackman & Eastop list 31 species of aphid as feeding on Sorghum bicolor (the principal modern sorghum crop species) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 11 as occurring in Britain (Show British list).

Damage and control

Melanaphis sacchari sp. group (probably mainly Melanaphis sorghi) has long been a common pest of sorghum in tropical Africa, Asia, the Far East and South America. In East Asia it is considered a major pest of sorghum. In the USA Melanaphis sacchari was present on sugarcane, but was not considered to cause much damage. Then in 2012 what later turned out to be Melanaphis sorghi was introduced into many south-eastern and central states of the USA where it soon became a major problem on sorghum.

Image copyright Patrick Porter, Bugwood.org under a CC BY-NC 3.0 license.

Management of the sugarcane aphid (mainly Melanaphis sorghi) is reviewed by Singh et al. (2004). Economic damage usually occurs in later growth stages. Heavily infested leaves such as in the picture above turn prematurely brown, and growth is stunted. Leaves below infected ones are often covered with sooty moulds further limiting growth and ultimately reducing yield. Plant stress due to drought may intensify damage to sorghum caused by the sugarcane aphid.

Some progress has been made in breeding aphid-resistant strains of sorghum. Cultural methods are also important including early planting to escape aphid attack, high density planting, destruction of ratoon sorghum to destroy overwintering aphids and mulching with rice/wheat straw. Natural enemies play an important role in suppressing aphid numbers.

Despite advances in use of the above methods, Singh et al. (2004) point out that currently the only effective method to control sugarcane aphid populations on sorghum is the use of insecticides. That usually involves soil application of systemic insecticides followed by foliar application of contact insecticides. If chemical control does have to be used, then systemic or selective insecticides are clearly preferable.

Acknowledgements We are grateful to Sunil Joshi & J. Poorani for permitting us to use their excellent images from Aphids of Karnataka. We have used the keys and species accounts of Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References Jaimes-Orduña, J. et al. (2020). Identification of predatory and parasitoid insect species associated with Melanaphis sacchari (Hemiptera: Aphididae), a sorghum pest in Nuevo León, Mexico. Florida Entomologist 103(1), 145-147. Full text Nibouche, S. et al. (2018). Invasion of sorghum in the Americas by a new sugarcane aphid aphid (Melanaphis sacchari superclone. PLoS ONE 13(4): e0196124. Full text Nibouche et al. (2021). Morphometric and molecular discrimination of the sugarcane aphid, Melanaphis sacchari, (Zehntner, 1897) and the sorghum aphid Melanaphis sorghi (Theobald, 1904). PLoS ONE 16(3): e0241881. Full text Singh, B.U. et al. (2004). Biology and management of the sugar cane aphid Melanaphis sacchari (Zehntner) (Homoptera: Aphididae), in sorghum: a review. Crop Protection 23, 739-755. Full text Theobald, F. (1904). The ’Dura’ Aphis or ’Asal Fly’. Report of the Wellcome Research Laboratories at the Gordon Memorial College, Khartoum, pp. 43–45. Zehntner, L (1897). Overzicht van de Zieken van het Suikerriet op Java. Mededelingen van het Proefstation “Oost-Java” Nieuwe Serie 37, 525–575.