Home


powered by FreeFind
 

Latest Release! NetObjects Fusion 9

Pests of bamboos cultivated in western gardens

While there are currently no invertebrate pests or diseases that threaten to kill ornamental bamboos in western cultivation, a range of bamboo pests can damage or disfigure them to varying degrees. Some have been around for decades or more, but others have appeared more recently. Given the large number of such organisms that feed on bamboos in their natural environments, great care is needed to avoid importing pests from abroad. Quarantine procedures should be strictly adhered to, and those who introduce bamboos should make themselves aware of the potential insects, mites, viruses and fungae they might be importing, along with the serious economic and ecological consequences of accidentally introducing a new pest or disease into a country or region. Buyers of bamboo plants should be very cautious and inspect their new purchases extremely carefully. Visitors to bamboo nurseries and gardens should also be careful not to bring home more than they bargained for on their clothes or in their hair.

A few of the more serious examples of damage seen in Europe and the pests that cause them are given below.  ... More

 

Examples of infestation with the causal organism

Damage

Cause

  Rounded patches, especially along midrib and

  edges of leaves

 

 

 Bamboo Spider Mite, Schizotetranychus spp.

 colonies under webbing on lower leaf surface

 

 Minute stippling all over leaves, especially in dry

 indoor environments

 

 Other spider mites, e.g. 2-spotted Spider Mite 

 Tetranychus urticae, on lower leaf surface

 Sticky patches and black mould on top of leaves

 with white empty insect skins (exoskeletons)

 

 Aphid colonies on lower leaf surfaces, Takecallis

 taiwanus)

 

 Discoloured patches

 

 

Eriophyoid mites on lower leaf surface, Jaranasia,

 black or grey, and (probably) Aceria, white

 

 Broad translucent galleries, edges going brown,

 with frass and pupa. Photo: Rai Hannover

 

 Dipteran leaf miner, Cerodontha unisetiorbita,

 less than 3mm long, lays eggs that develop into

 larvae that feed in the leaf. Photo: Rai Hannover

Cotton-like deposits around branches

 

 Mealybugs Balanococcus kwoni are revealed

 when sheaths are removed

 

Scale - females and crawlers under new sheath

 (left) and encrustations on older culm (right)

 

 The armoured Bamboo Scale Insect, Kuwanaspis

  pseudoleucaspis, with and without covering

 

DSCN7226_Crop-360 comp

Internal damage to culm in Nepal in 1983 (left).

 Entrance/exit hole, also showing damaged

 culm, in Yunnan in 1995 (right)

 

DSCN7256-360

Moth larvae inside culm in Nepal 1983, identified

  as noctuids in genus Pareuplexia. Similar larvae

  in Thailand have been identified as crambids

  Omphisa fuscidentalis

 

More ...

There are a wide range of vertebrate animals that will feed on bamboo foliage or new shoots if available within reach, including gophers, squirrels, voles, raccoons, deer, rabbits, pandas, gorillas, livestock, elephants, and of course man himself. In addition there are also thousands of invertebrate arthropods that are actual or potential pests. These include many insects (Class Insecta, 6 legs: Orders Diptera, Hemiptera, and Lepidoptera), but also spider mites, from Class Arachnida, usually with 8 legs, which includes the real spiders.

In their natural environments bamboos are components of a complex local ecology that includes many competing life forms, more or less in balance with each other. When plants are brought into cultivation elsewhere it is often the case that there will be some problems either for the introduced plants, or for the environment and ecological systems into which they are brought. Problems might arise because the introduced plants meet new enemies, eg the grey squirrel, or because old enemies are brought with them, without their own predators to keep them under control, eg the bamboo spider mite. The balance between predators and prey is altered by changing the constituents of any ecological system. The pests of bamboos in cultivation are best considered in this light, as ultimately a new balance must be reached. It is necessary to identify and understand the pests, their life cycles, and their ecology in their natural environments properly if they are to be handled effectively, just as we need to identify and understand individual bamboos in order to make the most of them. Both the diversity of cultivated bamboos, and the diversity, life cycles and ecology of their pests still need to be studied in more detail in their natural environments. Asian bamboos have literally thousands of invertebrate pests and diseases, see the ABS website for a comprehensive and frightening overview of all these by Mike Turner, and for further information on the more extensive range of bamboo pests found in the US. See the Technical Reports from INBAR on Asian diseases and insect pests (2 manuals, 12 downloads total).

It is important to realise that, with the notable exception of the 2-spotted spider mite, the pests of bamboos are nearly always host-specific, i.e. only found on bamboos. They are not just a general infestation that has spread from other plants. Growers and curators of collections should not be allowing them to proliferate, and everyone should be making strenuous efforts to avoid selling/exchanging plants with any pests.

 

Leaves

Bamboo leaves have a limited life span, longer for genera with thicker leaves, and will suffer various kinds of damage progressively over their natural life span of 2-5 years. Pest attack is most evident from attack of young leaves, which otherwise would be a healthy uniform colour, although environmental stress such as drought or cold can also damage young leaves.

Bamboo Spider Mites, Schizotetranychus celarius (Banks, 1917) and S. longus Saito, 1990, are the worst pest problem for bamboos introduced into the west, both in the US and now in Europe too. Predators that keep them under control in Asia have not yet been introduced, and native mite predators do not seem to have learnt that they have a new potential food source. The only reliable treatment is the removal of all above ground growth, which should be burnt, in a slash and burn or ‘scorched earth’ procedure. Repeated and thorough spraying of all the leaves on a regular basis for several months with insecticides/miticides, wetting agents and soaps can eventually eliminate them. In Europe many bamboo collections and some nurseries are now infested heavily or sporadically with these mites. Visitors and buyers should beware.

Other spider mites such as the ubiquitous 2-spotted greenhouse mite, Tetranychus urticae Koch, 1836, commonly found on many houseplants, are not often a problem outside, but can build up quickly indoors under hot dry conditions, leading to speckled leaves that fall off early, and a light but extensive webbing all over the plant. Insecticide sprays and biological control by predator mites are adequate for control. Indoor bamboos benefit from regular water spraying, and periodic, temporary relocation outside in wet(but not frosty) weather.

Eriophyoid mites are strange-looking, extremely small, conical mites with only 4 legs, rather than the 8 legs of the spider mites. To the naked eye they are only tiny black or grey spots. Even with a x10 hand lens it is hard to see that they are mites. These are currently rare and causing only sporadic damage in Europe and the US. Two species, from genera Jaranasia Chandrapatya & Boczek, 2000, and (probably) Aceria Keifer 1944, have been seen in the UK. They are apparently restricted to a very narrow range of hosts, and consequently may well have been introduced recently on bamboo plants from China. Their identification is as uncertain as that of the newly introduced bamboos on which they have been found. They do not produce galls in bamboos, instead producing speckled yellowed leaves with dark brown patches. It would appear that in the UK at least, they only become troublesome when bamboos are cultivated indoors or under glass, in very dry conditions, and they can usually be controlled by maintaining higher humidity levels.

Bamboo aphids (Order Hemiptera; Suborder Sternorrhyncha; Family Aphididae; Subfamily Myzocallidinae) from the genus Takecallis Matsumura, 1917, falling under the general garden term of greenfly, can be a nuisance when there is a heavy infestation, as the honeydew they excrete onto the leaves below is sticky and leads to growth of unsightly black fungus. The problem may be seasonal or localised, often exacerbated by a mild winter. Natural predators such as ladybird beetles and their larvae abound. Native ones are not fussy about the origin of their prey, and the introduction of the non-native Harlequin Ladybird is helping to keep the numbers down. The bamboo-feeding species also seem susceptible to a variety of pesticides, as well as the usual aphid deterrents and treatments, such as chilli pepper spray. Four species are now common in Europe, all introduced from Asia. T. arundinariae (Essig, 1917) is a pale translucent aphid with pretty winged forms with 2 rows of dashes. T. arundicolens (Clarke, 1903) has wingless forms identical to those of T. arundinariae, but the winged forms do not have rows of spots, having tiny but distinct spherical black ‘tails’ instead. Takecallis taiwanus (Takahashi, 1926) is much greener, the winged forms lacking easily distinguishable characters, but the wingless forms having 4 prominent rows of dorsal bristles. New for 2015 in the UK is a fourth species, which spreads very fast, slightly smaller than the others, yellow rather than white or green, the winged forms having no dashes or black tail, but all-black antennae. This species keys out (Qiao & Zhang 2004) to T. takehashii (Hsu, 1980), a little-known species from Taiwan, but the identification has not yet been confirmed by an entomologist.

Several different leaf-rolling insects are a very serious pest in Asia, and some are reported in the US, but they are not yet found in Europe, although some native insects that usually live on other plants may roll the occasional bamboo leaf.

Leaf miners (Order Diptera; Family Agromyzidae) are the next category of pest that have been imported from Asia to Europe, and plants should be checked for translucent areas in which the small larvae have been feeding within the leaf. The miner, which has been identified as Cerodontha unisetiorbita Slobin, 1993, has now been introduced to Italy, Switzerland, Czech Republic and Germany. It is a very small black fly that is unlikely to be seen, with pale larvae that cause the damage, and red-brown pupae.

 

Culms and shoots

Various insects can live on the surface or in the hollow interior of bamboo culms, but the main pests of western bamboos live on the surface and are from Order Hemiptera; Suborder Sternorrhyncha. They are woolly aphids (Superfamily Aphidoideae; Family Aphididae; Subfamily Eriosomatinae), and various scale insects from Superfamily Coccoidea. Armoured scale insects are from Family Diaspididae, soft scale insects are from Family Asterolecaniidae and mealybugs, the unarmoured, i.e. scale-less, scale insects are from Family Pseudococcidae.

Originating in tropical and subtropical areas, woolly aphids such as Pseudoregma bambucicola (Takahashi, 1921) (syn. Pseudoregma bambusicola Szelegiewicz, 1968), are only likely to occur on bamboo collections under glass in Europe. Unlike other aphids, they cover and feed on new shoots and branches rather than leaves, while producing the same messy sugary exudations in a similar fashion.

Scale insects come in different shapes and forms, from soft, walking mealybugs to resilient relatives fixed under armoured shields. Incidence in European bamboos has just been reviewed (Ülgentürk et al, 2014).

Armoured scale insects have recently become much more prevalent in bamboos in Europe, although some have apparently been present for a long time. Most notable is Bamboo Scale, Kuwanaspis pseudoleucaspis (Kuwana, 1923). The females crawl up to a new permanent location under a small orange scale in the summer, then grow under old moulted scales and a white waxy extension, together forming an oyster-shaped covering, under which they overwinter. Their favourite location is under culm sheaths and branch sheaths, but they are also found on leaf petioles and under leaf bases in autumn when they have become well established in a clump. As is the case with armoured scales on other plants, they are difficult to eradicate completely from bamboos without total destruction of all above-ground growth. The insect body is soft and vulnerable, but the mature female lives under hard scales and the waxy extension, protected from predators, weather and chemical treatment. Hard frost and dampness seems to kill most exposed adults, but when a tough, persistent bamboo culm sheath or a dense branch cluster is added to the equation, eliminating this customer is not an easy task. Annual removal of persistent culm sheaths, especially those near the base of the culm, along with regular removal of the older, more branched, culms on which they tend to accumulate, can keep it under control and eliminate it eventually. Spraying with insecticide in early summer, when the apparently more vulnerable young crawlers emerge from their waxy shelter, is supposedly effective to some degree, but the timing must be precise. Other Asian diaspids, including 3 Odonaspis species are found in southern Europe, Turkey seeming to be a main entry point. O. greeni (Cockerell, 1902) is illustrated in Soria et al. 1998.

Soft scale insects, also known as pit scales because they cause small depressions on some plants (not bamboos), are similar to armoured scales but inhabit a softer, rounder scale, the test. They have a shorter life and are pests of subtropical areas and collections under glass, eg Bambusaspis bambusae (Boisduval, 1869) on Bambusa in the Eden Project, Cornwall.

Mealybugs, unarmoured scale insects, are similar to woolly aphids in their waxiness, but do not have the pear-shaped bodies or obvious long legs of aphids, nor the scale of the armoured and pit scale insects. Although unlikely to seriously affect the growth of bamboos in cooler climates, they are unsightly and spread fast. Like the woolly aphids, they can form dense colonies and also exude sticky sap, but they feed mainly on young branch shoots under the culm sheaths. Balanococcus kwoni Pellizzari & Danzig, 2007 is now commonly encountered on nursery stock in much of Europe. The giant bamboo mealybug Chaetococcus bambusae (Maskell, 1893) is probably only going to be a pest of bamboo collections under glass, eg on Bambusa in the Eden Project in Cornwall. Natural control from native predators including ladybird beetles can apparently keep numbers down, and mealybugs are from warm climates and may be checked somewhat by cold weather. Removal of culm sheaths, branch clusters and older culms should help to reduce numbers, especially out of doors. They are susceptible to chemical treatments, but their waxiness and their habit of hiding under sheaths gives them good protection. Even systemic treatments may not be completely effective. They can survive in the soil and may even feed on the roots and rhizome shoots. Prevention is always better than cure. Check new plants, keep them isolated, and destroy infested plants completely as soon as possible.

Inhabitants of the bamboo culm and cavity include shoot borers, which eat into soft new shoots. They can cause substantial, unsightly damage, and lead to death or disfiguration of many new shoots in Nepal and probably other Asian countries. In Europe & the US native borers adapted to similar plants such as maize have attacked bamboos. Fortunately no shoot borers specific to bamboos have been introduced so far, although this could happen easily as the larvae come from an unexpected group of insects, the moths (Order Lepidoptera), which can overwinter in large numbers as pupae hidden inside the culm, or in soil or leaf litter as a hard individual chrysalis. In addition, bamboo shoot borer larvae are often highly prized as a culinary delicacy in Asia, and will probably be introduced deliberately into cultivated bamboos in warmer countries.

When I described the pattern of damage, the unusual life cycle overwintering inside the culm, and potential control measures for shoot-boring moth larvae in Nepal (Stapleton 1985, 1987), there was a certain amount of eyebrow-raising from local entomologists at the time, as conventional wisdom in S Asia was that this damage was caused by the bamboo hispine beetle Estigmena chinensis and Cyrtoctrachelus weevils instead. Noctuid moths were known to cause damage in China, but they are rather different, overwintering in the soil, making control difficult. Samples of moths I considered responsible for the damage in Nepal were identified by the Natural History Museum (London) in 1985 as a noctuid moth from the genus Pareuplexia.

A pyralid moth, Epiparbattia gloriosalis Caradja, was later reported as having a similar life cycle in culms of Sinocalamus latiflorus in S China, in the review of bamboo insect pests of Asia by Wang et al. (1998). A crambid moth, Omphisa fuscidentalis Hampson was also later identified as overwintering in bamboo culms in Thailand, Laos, Burma & Yunnan (Singitrop et al., 1999), in much the same way as the moth from Nepal, but was reported as not damaging the culms, if anything making them stronger. The larvae of this species are the economically important edible variety, now known as ‘bamboo worms’. The pattern of damage I reported in Nepal with slits in the culm in 1985 does indeed look different to swollen but intact culms I saw in S Yunnan in 1995, see photos above. Further work is still required to identify and study the life cycles and damage caused by these pests.

Many thanks to Drs Daniel Pye and Chris Malumphy, entomologists at the UK Food and Environment Research Agency (Fera), for authoritative identification of the mites and the scale & aphids respectively, and for information on occurrences in the UK.

 

Higuchi, M. (1968). A revision of the genus Takecallis Matsumura (Homoptera: Aphididae). Insecta Matsumurana 31(4): 25-33.

Qiao, G.X. & Zhang, G.X. (2004). Review of the genus Takecallis Matsumura (Homoptera: Aphididae: Myzocallidinae) from China and description of one new species. The Raffles Bulletin of Zoology 52(2): 373-378.

Ülgentürk, S., Porcelli, F., & Pellizzari, G. (2014). The Scale Insects (Hemiptera: Coccoidea) on Bamboos in the Western-Palearctic Region: New Records and Distributional Data. Acta zool. bulg., Suppl. 6, 2014: 77-82.

Stapleton, C.M.A. (1985). Noctuid shoot borers in Dendrocalamus and Bambusa species. Nepal Forestry Tech. Info. Bull. 11: 26-31.

Stapleton, C.M.A. (1987). Bamboos. In: J. K. Jackson, Manual of Afforestation in Nepal: 199–214. Forestry Research Project, Kathmandu.

Tippawan Singtripop, Somsak Wanichacheewa, Seiji Tsuzuki, & Sho Sakurai (1999). Larval Growth and Diapause in a Tropical Moth, Omphisa fuscidentalis Hampson. Zoological Science 16: 725–733.

Wang, H.J., Varma, R.V., & Xu, T.S. (1998). Insect Pests of Bamboos in Asia: An Illustrated Manual. INBAR Technical Report No. 13. INBAR, New Delhi.

Xue, X.F., Song, Z.W., Amrine, J.W., & Hong, X.Y. (2006). Eriophyid Mites (Acari: Eriophyoidea) on Bamboo from China, with Descriptions of Three New Species from the Qinling Mountains. Annals of the Entomological Society of America 99.6 (2006): 1057-1063.

 

[Home] [Introduction] [Background] [Identification] [Cultivated Bamboos] [Morphology] [Classification] [Nomenclature] [Origins] [Pests] [Author] [Publications]