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Pentalonia nigronervosaBanana aphidOn this page: Identification & Distribution Other aphids on the same host Damage & ControlIdentification & DistributionAdult apterae of Pentalonia nigronervosa (see first picture below) are reddish-brown to blackish, with the antennal bases and apices, apical parts of femora and siphunculi dark and cauda dusky. The antennal tubercles are small and pointed. The antennae are about as long as the body with a long terminal process which is 6.2-7.5 times as long as of the base of segment VI. The rostrum reaches to behind the hind coxae, and the apical rostral segment (RIV+V) is 1.6-2.1 times as long as the second hind tarsal segment. RIV+V is nearly always more than 0.137 mm long (cf. Pentalonia caladii on Zingiberaceae and Araceae, which has RIV+V less than 0.137 mm). The siphunculi are 2.8-4.1 times the caudal length, with their distal 0.25 more-or-less swollen symmetrically. The siphunculi and femora are covered with irregular, transverse rows of spicules. The cauda is constricted near its base, divided into a basal, globoid part and an apical finger-shaped part, and bears 4 hairs. The body length of adult Pentalonia nigronervosa apterae is 1.2-1.8 mm. Note: In the past Pentalonia caladii, found on Zingiberaceae and Araceae, was thought to be a form of Pentalonia nigronervosa. The situation was clarified by Foottit et al (2010) using molecular and morphometric analysis, and the name nigronervosa is now restricted to the banana-feeding aphids.
Images above copyright Scot Nelson, public domain. Immature Pentalonia nigronervosa (see picture below) are similar to adult apterae, but are generally a paler brown in colour.
Image above copyright Scot Nelson, public domain. Alatae of Pentalonia nigronervosa (see pictures top right & second below) have antennae about 1.2 times the body length, with a long terminal process, and 2-12 secondary rhinaria on segment III, 0-10 on segment IV and 0-6 on segment V. The wing veins are broadly shadowed with brown, with brown spots at their apices. The middle part of the radial sector of the forewing is fused with the media vein. The images below show clarified mounts of an apterous vivipara and an alate vivipara.
Clarified mount images above copyright Brendan Wray, Bugwood.org under a Creative Commons Attribution-Noncommercial 3.0 License.
Images above copyright Scot Nelson, public domain. Pentalonia nigronervosa feeds almost entirely on plants in the family Musaceae, with a few records from Heliconiaceae and Zingiberaceae. It is often found living under the old leaf bases, and is usually ant-attended (see first two pictures above). Alate males have been recorded, but in most places populations are thought to be entirely anholocyclic. It is an important vector of banana bunchy top virus (see third picture above) which has severely affected banana production in some parts of the world (e.g. Samoa & Tonga). Pentalonia nigronervosa is widespread through all tropical and subtropical parts of the world, and in glasshouses in Europe, Australia and North America. Other aphids on the same hostPentalonia nigronervosa has been recorded on 8 Musa (=Ensete) species (Musa acuminata, Musa balbisiana, Musa formosana, Musa nana, Musa ×paradisiaca, Musa ×sapientum, Musa superba, Musa textilis). Blackman & Eastop list 14 species of aphid as feeding on banana (Musa spp.) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 10 as occurring in Britain (Show British list).
Damage and controlPentalonia nigronervosa damages banana plants in three ways. Firstly there is a certain amount of direct feeding damage as the aphids remove nutrients and water from the plant. Secondly, the aphids produce honeydew which encourage the growth of sooty moulds. Lastly they transmit viruses, in this case banana bunchy top virus (BBTV). Most damage to banana plants is caused by transmission of BBTV - which is known to occur in about 37 countries in Africa, Asia and South Pacific Islands. Plants infected with this virus have upright, stunted leaves which turn yellow and tend to cluster at the growing apex. All banana (Musa) species and varieties are susceptible to BBTV, although some varieties like Gros Michel are somewhat more resistant than others. Cultural control measures include good weed control around the banana patch, and pruning unwanted suckers which can support high aphid populations. Biological control has been attempted with the introduction of predators, but has had little impact. Chemical control of the aphid is carried out using approved insecticides and soap/oil mixtures. More information on the diagnosis and control of BBTV is given by ALLIANCE.
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