Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Papuana huebneri
(taro beetle)

Toolbox

Datasheet

Papuana huebneri (taro beetle)

Summary

  • Last modified
  • 18 December 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Natural Enemy
  • Preferred Scientific Name
  • Papuana huebneri
  • Preferred Common Name
  • taro beetle
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • Papuana huebneri is one of at least 19 species of known taro beetles native to the Indo-Pacific region; it is native to Papua New Guinea, the Molucca Islands in Indonesia, the Solomon Islands and Vanuatu, and h...

  • Principal Source
  • Draft datasheet under review.

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report

Pictures

Top of page
PictureTitleCaptionCopyright
Papuana huebneri, taro beetle); adult male, dorsal view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
TitleAdult male
CaptionPapuana huebneri, taro beetle); adult male, dorsal view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
Copyright©Muséum National d’Histoire Naturelle, Paris (MNHN)/Antoine Mantilleri-2015 - CC BY-NC-ND 4.0
Papuana huebneri, taro beetle); adult male, dorsal view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
Adult malePapuana huebneri, taro beetle); adult male, dorsal view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.©Muséum National d’Histoire Naturelle, Paris (MNHN)/Antoine Mantilleri-2015 - CC BY-NC-ND 4.0
Papuana huebneri, taro beetle); adult male, lateral view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
TitleAdult male
CaptionPapuana huebneri, taro beetle); adult male, lateral view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
Copyright©Muséum National d’Histoire Naturelle, Paris (MNHN)/Antoine Mantilleri-2015 - CC BY-NC-ND 4.0
Papuana huebneri, taro beetle); adult male, lateral view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.
Adult malePapuana huebneri, taro beetle); adult male, lateral view. Collected from Papua New Guinea, Île du Duc-d'York. Museum set specimen. Note scale.©Muséum National d’Histoire Naturelle, Paris (MNHN)/Antoine Mantilleri-2015 - CC BY-NC-ND 4.0

Identity

Top of page

Preferred Scientific Name

  • Papuana huebneri (Fairmaire, 1879)

Preferred Common Name

  • taro beetle

Other Scientific Names

  • Papuana fallax Prell, 1934
  • Pimelopus huebneri Fairmaire, 1879
  • Pimelopus pygmaea Aulmann, 1911

International Common Names

  • English: babai beetle; bwabwai beetle; dalo pest; rhinoceros beetle
  • French: scarabée du taro

Local Common Names

  • Fiji: dalo bitol
  • Papua New Guinea: binatang bilong taro; taro bitol

Summary of Invasiveness

Top of page

Papuana huebneri is one of at least 19 species of known taro beetles native to the Indo-Pacific region; it is native to Papua New Guinea, the Molucca Islands in Indonesia, the Solomon Islands and Vanuatu, and has been introduced to Kiribati. Taro (Colocasia esculenta) is an important crop in these countries; high infestations of P. huebneri can completely destroy taro corms, and low infestations can reduce their marketability. The beetle also attacks swamp taro or babai (Cyrtosperma chamissonis [Cyrtosperma merkusii]), which is grown for consumption on ceremonial occasions. Infestations of taro beetles, including P. huebneri, have led to the abandonment of taro and swamp taro pits in the Solomon Islands and Kiribati, resulting in the loss of genetic diversity of these crops and undermining cultural traditions. P. huebneri also attacks a variety of other plants, although usually less seriously. Management today relies on an integrated pest management strategy, combining cultural control measures with the use of insecticides and the fungal pathogen Metarhizium anisopliae.

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Coleoptera
  •                         Family: Scarabaeidae
  •                             Genus: Papuana
  •                                 Species: Papuana huebneri

Notes on Taxonomy and Nomenclature

Top of page

Papuana huebneri is a scarabaeid beetle in the subfamily Dynastinae. It is one of at least 19 species of known taro beetles: 18 in the genus Papuana, and Eucopidocaulus tridentipes (previously Papuana tridentipes) (Biosecurity Australia, 2011). Other species of taro beetles in the genus Papuana include P. woodlarkiana, P. biroi, P. uninodis and P. trinodosa (Onwueme, 1999).

Papuana huebneri has two subspecies: P. huebneri huebneri and P. huebneri fallax (GBIF, 2015).

Description

Top of page

Adult Papuana huebneri are black, shiny and 15-20 mm long. The size and number of head horns in taro beetles varies between species and sexes; P. huebneri has only one small horn, which is larger in the male than the female (Macfarlane, 1987a).

The newly hatched larvae are white, 4-5 mm long and C-shaped at rest (Macfarlane, 1987a). They undergo three moults and when fully grown after 3-4 months they are 34-40 mm long.

Distribution

Top of page

Taro beetles as a group are native to the Indo-Pacific region, including Indonesia, Papua New Guinea, Solomon Islands, Vanuatu, Fiji and New Caledonia (Onwueme, 1999). About 11 or 12 species are serious pests of taro in the South Pacific region, and there have been a number of records of Papuana species in Australia between 1909 and 1981 (Biosecurity Australia, 2011).

Papuana huebneri is endemic to the West Pacific (Jackson, 1992) and has been reported from Papua New Guinea (Centre for Overseas Pest Research, 1978; APPPC,1987; Masamdu and Simbiken, 2001); the Bismarck Archipelago (Centre for Overseas Pest Research, 1978); New Britain (Schuhbeck and Bokosou, 2006); Vanuatu (APPPC, 1987); the Molucca Islands (Centre for Overseas Pest Research, 1978); the Solomon Islands (APPPC, 1987; Masamdu and Simbiken, 2001; French, 2010); and (introduced) Kiribati (= the Gilbert Islands) (Food and Agriculture Organization, 1974; APPPC, 1987; Centre for Overseas Pest Research, 1978; Dharmaraju, 1982; Sandhu et al., 1992; Theunis and Teuriara, 1998).

Distribution Table

Top of page

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 10 Jan 2020
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes

Asia

IndonesiaPresent, LocalizedNativeCABI (Undated)Present based on regional distribution
-Maluku IslandsPresentNativeUK, Centre for Overseas Pest Research (1978)

Oceania

FijiAbsent, Invalid presence record(s)Macfarlane B (1987); Singh (1984)
KiribatiPresentIntroduced1934Food and Agriculture Organization (1974); UK, Centre for Overseas Pest Research (1978); Dharmaraju (1982); APPPC (1987); Sandhu and Teaotai (1992); Theunis and Teuriara (1998); Jackson and Klein (2006)
New CaledoniaAbsent, Unconfirmed presence record(s)TaroPest (2015); Varin D and Vernier P (1996)
Papua New GuineaPresentNativeUK, Centre for Overseas Pest Research (1978); APPPC (1987); Schuhbeck and Bokosou (2006)Including Bismarck Archipelago (in turn including New Britain)
Solomon IslandsPresentNativeAPPPC (1987)
VanuatuPresentNativeAPPPC (1987)

History of Introduction and Spread

Top of page

Papuana huebneri was accidentally introduced to Kiribati in 1934 (Jackson and Klein, 2006).

A taro beetle thought to be Papuana huebneri was reported for the first time in Fiji in June 1984 from a small area at Veisari near Suva (Singh, 1984), but subsequent studies showed that the beetle was actually Papuana uninodis and not P. huebneri (Macfarlane, 1987b).

Papuana huebneri was reported from New Caledonia for the first time in 1993, causing only mild damage at that time (Varin and Vernier, 1996; Onwueme, 1999), although the beetle species has not been fully authenticated (TaroPest, 2015).

Introductions

Top of page
Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Kiribati 1934 Yes No Jackson and Klein (2006)

Risk of Introduction

Top of page

Papuana beetles are considered a serious potential threat to taro production in countries and islands where they do not yet occur. They can be transported as hitchhikers on ships or other vehicles, in infested soil or other materials, or in taro corms or propagating material. Strict quarantine measures must be observed to prevent the spread of taro beetles between countries.

Habitat

Top of page

Adult Papuana huebneri live in the underground parts of taro (Colocasia esculenta) and other crops; oviposition and larval development take place in moist soil under rotten logs and decaying vegetation, in the roots of grasses with silty loam topsoil, and on the banks of rivers and streams with good alluvial soil deposits. Disturbed environments make good oviposition sites because of the availability of alternative host plants.

Hosts/Species Affected

Top of page

Papuana huebneri is a pest of taro (Colocasia esculenta; known as ‘dalo’ in Fijian; McGlashan, 2006) (Masamdu, 2001; International Business Publications, 2010), which is grown primarily as a subsistence crop in many Pacific Island countries, including Kiribati, Papua New Guinea, the Solomon Islands and Vanuatu, where P. huebneri is found (Aloalii et al., 1993). Taro also has value in gift-giving and ceremonial activities (Braidotti, 2006; Lal, 2008). The beetle also attacks swamp taro or babai (Cyrtosperma merkusii or Cyrtosperma chamissonis), which is grown for consumption on ceremonial occasions (Food and Agriculture Organization, 1974; Dharmaraju, 1982; International Business Publications, 2010).

Other plants attacked by Papuana huebneri include tannia (Xanthosoma sagittifolium), bananas (Musa spp.), Canna lily (Canna indica), pandanus (Pandanus odoratissimus [Pandanus utilis or P. odorifer]), the bark of tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao), the fern Angiopteris evecta (Masamdu, 2001), and occasionally the Chinese cabbage Brassica chinensis [Brassica rapa] (International Business Publications, 2010).

Species of Papuana behave similarly to each other and feed on the same host plants (TaroPest, 2015).  For taro beetles in general, primary host plants other than taro include giant taro (Alocasia macrorrhizzos), Amorphophallus spp., the fern Angiopteris evecta, banana (Musa spp.) and tannia (Xanthosoma sagittifolium). Secondary hosts include pineapple (Ananas comosus), groundnut (Arachis hypogaea), betel nut (Areca catechu), cabbage (Brassica oleracea), canna lily (Canna indica), coconut (Cocos nucifera), Commelina spp., Crinum spp., yam (Dioscorea spp.), oil palm (Elaeis guineensis), sweet potato (Ipomoea batatas), Marattia spp., pandanus (Pandanus odoratissimus [Pandanus utilis or P. odorifer]), Saccharum spp. including sugarcane (Saccharum officinarum) and Saccharum edule [Saccharum spontaneum var. edulis], and potato (Solanum tuberosum); they occasionally ring bark young tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao) plants (Macfarlane, 1987b; Aloalii et al., 1993; Masamdu and Simbiken, 2001; Masamdu, 2001; Tsatsia and Jackson, 2014; TaroPest, 2015).

Host Plants and Other Plants Affected

Top of page

Growth Stages

Top of page Post-harvest, Seedling stage, Vegetative growing stage

Symptoms

Top of page

Adult taro beetles burrow into the soft trunks, plant bases and corms of a range of plants, including taro, making large holes or cavities up to 2 cm in diameter (McGlashan, 2006). The feeding tunnels and associated frass may be visible in infested corms (Biosecurity Australia, 2011). The amount of damage to the crop depends on the age of the plants when attacked and the density of infestation. Feeding activity can cause wilting and even the death of affected plants, particularly in young plants if the beetles bore into the growing points. Older plants infested by beetles grow slowly and a few or all of the leaves wilt (TaroPest, 2015). In severely damaged plants tunnels may run together to form large cavities, making the damaged corms more susceptible to fungal infections (Macfarlane, 1987a; Onwueme, 1999). Similar symptoms of damage are caused to other root crops, e.g. sweet potato, yams and potato (McGlashan, 2006). Taro beetles can ring-bark young tea, cocoa and coffee plants in the field and bore into seedlings of oil palm and cocoa (Aloalii et al., 1993).

List of Symptoms/Signs

Top of page
SignLife StagesType
Growing point / internal feeding; boring
Growing point / wilt
Leaves / wilting
Roots / external feeding
Roots / internal feeding
Stems / internal feeding
Stems / visible frass
Stems / wilt
Vegetative organs / frass visible
Vegetative organs / internal feeding
Whole plant / internal feeding
Whole plant / plant dead; dieback
Whole plant / wilt

Biology and Ecology

Top of page

Much of the information available on taro beetle biology refers to taro beetles in general rather than Papuana huebneri in particular. In Papua New Guinea, the life cycle of P. huebneri is about 20 weeks (Perry, 1977, cited in Aloalii et al., 1993). Newly emerged adults fly from the breeding sites to taro fields and tunnel into the soil at the base of the taro corm, where they feed on the growing corm. Mating takes place in the corm. Gravid females leave the taro corm about 7 weeks after adult emergence and fly to neighbouring vegetation for oviposition (Macfarlane, 1987a).

Eggs are laid singly 5-15 cm beneath the soil surface close to a host plant (Jackson, 1980). Preferred oviposition sites are in moist soil under rotten logs and decaying vegetation, in the roots of grasses with silty loam topsoil, and on the banks of rivers and streams with good alluvial soil deposits. Disturbed environments (logging areas, gardens under fallow, road sides) make good oviposition sites because of the availability of alternative host plants (TaroPest, 2015). The average number of eggs laid per female is 70. Newly laid eggs are oval, white and soft and 2-3 mm long, and they enlarge to up to three times their original size (Macfarlane, 1987a). The gravid female continues to lay fertile eggs for up to 3 months (TaroPest, 2015).

Larvae hatch in 11-16 days. The newly hatched larvae are white, 4-5 mm long and C-shaped at rest (Macfarlane, 1987a). In common with other species of Dynastinae, the larvae feed on plant stems and roots and organic matter in soil humus or litter. They turn these substrates into energy through microbial action in a modified gut (Jackson and Klein, 2006). Taro beetles use a wide range of plants for breeding, including Johnson grass (Sorghum verticilliflorum [Sorghum arundinaceum]), elephant grass (Pennisetum purpureum), kunai (Imperata cylindrica) and Phragmites karka (Onwueme, 1999). Larvae are rarely found feeding on taro corms but have been found among the roots of Saccharum edule [Saccharum spontaneum var. edulis] (locally known as pitpit) and sugarcane in Papua New Guinea (Macfarlane, 1987a). Larvae undergo three moults and when fully grown after 3-4 months they are 34-40 mm long. The prepupal and pupal stages occur in a chamber in the soil and the adult emerges about 3 weeks after pupation (Macfarlane, 1987a; Masamdu, 2001).

Adult taro beetles live for 4-8 months (Onwueme, 1999). They are active from dusk to around midnight (Masamdu and Simbiken, 2001). Male beetles are less mobile than females, remaining in the taro corms after mating, while the females leave the corms to search for oviposition sites. Beetles remaining in the corms are therefore most likely to be males (Biosecurity Australia, 2011). Adult taro beetles are capable of flying up to 1 km and they are attracted to lights (Tsatsia and Jackson, 2014).

Climate

Top of page
ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))

Natural enemies

Top of page
Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Austroscolia nitida punctatissima Parasite Larvae not specific
Formosia solomonicola Parasite Larvae not specific
Metarhizium anisopliae Pathogen Other/All Stages not specific Papua New Guinea, Solomon Islands, Kiribati Taro (Colocasia esculenta)
Oryctes rhinoceros nudivirus Pathogen Larvae/Other/Adult Female/Other/Adult Male not specific Papua New Guinea, Solomon Islands, Kiribati Taro (Colocasia esculenta)
Paenibacillus popilliae Pathogen not specific Kiribati
Scolia nitida Parasite Larvae not specific
Steinernema glaseri Parasite Other/Adult Female/Other/Adult Male not specific
Vavraia Pathogen not specific

Notes on Natural Enemies

Top of page

Several natural enemies of Papuana huebneri or other taro beetles have been recorded, including the fungus Metarhizium anisopliae and the bacterium Paenibacillus popilliae (formerly Bacillus popilliae) (Theunis and Teuriara, 1998; Onwueme, 1999) and the protozoan Vavraia (Onwueme, 1999). Larval parasites recorded include a species of Formosia (Diptera: Tachinidae) in Papua New Guinea and Scolia nitida (Hymenoptera, Scoliidae) in the Solomon Islands (Macfarlane, 1987a). The Secretariat of the Pacific Community/European Union (SPC/EU) Taro Beetle Management (TBM) project recorded the tachinid Formosia solomonicola Baranov, 1936 and the scoliid Austroscolia nitida punctatissima (Kirby) [misspelt as Austrocolia nitida punctassima] from P. huebneri (Lal, 2008). The cane toad (Bufo marinus [Rhinella marina]), rats, bandicoots and pigs have also been reported as predators of taro beetles in Papua New Guinea (Tsatsia and Jackson, 2014; TaroPest, 2015).

Means of Movement and Dispersal

Top of page

There are a number of ways in which Papuana beetles can be transported accidentally between (or within) islands.

As the beetles are attracted to lights it is possible that they may be transported to new areas as hitchhikers on boats, ships or other vehicles.

All stages can be transported in infested soil, gravel and water.

Eggs, small larvae and adults could be transported in taro propagating material or inside taro corms (TaroPest, 2015). The likelihood that taro beetles will be transported in a viable state via the importation of fresh taro corms is thought to be low, because gravid females leave corms for oviposition and are therefore unlikely to occur in corms that have undergone harvest (Biosecurity Australia, 2011). However, as an adult beetle can survive for several weeks without feeding, and a fertile female can lay viable eggs for up to 3 months without mating again, one mature female is sufficient to start a new infestation (TaroPest, 2015).

Pathway Causes

Top of page
CauseNotesLong DistanceLocalReferences
HitchhikerShips, boats, other vehicles, soil, gravel, water, taro corms and taro propagating material Yes Yes
Self-propelled Yes

Pathway Vectors

Top of page
VectorNotesLong DistanceLocalReferences
Host and vector organismsTaro corms or propagating material Yes Yes
Plants or parts of plantsTaro corms or propagating material Yes Yes
Ship structures above the water line Yes
Land vehicles Yes
Soil, sand and gravel Yes Yes
Water Yes Yes

Plant Trade

Top of page
Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Bulbs/Tubers/Corms/Rhizomes adults; eggs; larvae Yes Pest or symptoms usually invisible

Impact Summary

Top of page
CategoryImpact
Cultural/amenity Negative
Economic/livelihood Negative

Economic Impact

Top of page

Papuana huebneri is a pest of taro (Colocasia esculenta; known as ‘dalo’ in Fijian; McGlashan, 2006), which is grown primarily as a subsistence crop in any Pacific Island countries, including Kiribati, Papua New Guinea, the Solomon Islands and Vanuatu, where P. huebneri is found (Aloalii et al., 1993). Taro also has value in gift-giving and ceremonial activities (Braidotti, 2006; Lal, 2008). The beetle also attacks swamp taro or babai (Cyrtosperma chamissonis [Cyrtosperma merkusii]), which is grown for consumption on ceremonial occasions (Food and Agriculture Organization, 1974; Dharmaraju, 1982). High infestations of taro beetles such as P. huebneri can completely destroy taro corms, and low infestations can reduce their marketability (Macfarlane, 1987a). Damage levels as low as 15% can make corms unmarketable and severely damaged corms cannot be used for home consumption or livestock feed (Carmichael et al., 2008). In Papua New Guinea it is estimated that taro beetles (as a group) can damage up to 30% of the taro crop (McGlashan, 2006; Lal, 2008), and losses of up to 80% have been recorded (TaroPest, 2015). Where many adults are present, newly planted setts may be killed by the beetles boring into the growing points (Macfarlane, 1987a). The spread of taro beetles has adverse environmental and social impacts, and has led to farmers burning and abandoning beetle-infested taro plots and cultivating new land in an effort to obtain one crop cycle without beetle infestation (McGlashan, 2006). In many parts of the Solomon Islands and Kiribati, Papuana beetles are one of the reasons farmers have abandoned the cultivation of taro, resulting in a loss of genetic diversity of taro as a staple food crop and undermining cultural traditions (Jackson and Klein, 2006; Tsatsia and Jackson, 2014). P. huebneri has contributed to the abandonment of swamp taro pits on South Tarawa and parts of North Tarawa in Kiribati (Thomas, 2002; Thomas 2003).

Two methods are used to assess the level of damage to taro by Papuana beetles. The first categorizes the number and weight of corms into one of five categories, from undamaged and saleable, to severely damaged and not even suitable for animal consumption. The second calculates the weight of taro consumed by the beetles, and hence yield loss per plant or unit area. The latter method has shown that even a small amount of damage substantially reduces the market value of the taro corms (Aloalii et al., 1993).

Social Impact

Top of page

If farmers are forced to stop growing taro this can undermine cultural traditions.

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
Impact outcomes
  • Host damage
  • Negatively impacts agriculture
  • Negatively impacts cultural/traditional practices
  • Negatively impacts livelihoods
  • Negatively impacts trade/international relations
Impact mechanisms
  • Herbivory/grazing/browsing
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Highly likely to be transported internationally illegally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Detection and Inspection

Top of page

Taro beetles can be detected by: (1) digging up wilting taro plants and examining them for signs of damage; (2) using light traps, particularly on moonless and rainy nights; and (3) sampling wild plant species (e.g. banana, sugarcane and grasses such as Paspalum spp. and Brachiaria mutica) at breeding sites, especially along river banks, on rotting logs and in compost heaps (Carmichael et al., 2008; Tsatsia and Jackson, 2014; TaroPest, 2015).

Prevention and Control

Top of page

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

Papuana beetles are very difficult to eradicate once they have become established, and are considered a serious potential threat to taro production in countries and islands where they do not yet occur. Strict quarantine measures must be observed to prevent the spread of taro beetles between countries.

SPS measures

The movement of taro-propagating material between countries should be limited to small quantities of sterile plantlets for scientific purposes under supervision of specialist agricultural officers. If it is necessary to import corms they should be washed free of soil, the tops cut off and the buds removed, and careful inspection should be made for any holes caused by taro beetles (Macfarlane, 1987a). As alternatives to now banned fumigants, other treatments of imported corms are being tested, including high-pressure washing and hot water treatment (Jamieson et al., 2016, 2018).

Control

Numerous efforts have been made to develop effective control measures for taro beetles. Cultural control measures tested include the use of tolerant varieties, the application of wood ash to the planting hole, dryland and wetland cultivation, the use of bananas or Saccharum edule [Saccharum spontaneum var. edulis] as trap and barrier crops, mulching, intercropping, repellent plants and time of planting (Macfarlane, 1987a; Aloalii et al., 1993; Varin and Vernier, 1996). The use of physical barriers such as fly wire or shade cloth spread over the soil was found to be ineffective (Onwueme, 1999). In the Solomon Islands, mulching of taro plants was actually found to increase taro beetle attack and is not recommended (Macfarlane, 1987a). Varietal differences in susceptibility to taro beetles have been reported in Papua New Guinea and the Solomon Islands but no useful resistance has been found. In Kiribati, P. huebneri preferred the giant swamp variety ‘ikaroi’ rather than ‘katutu’ (Macfarlane, 1987a).

Chemical control

Early control measures of scarabs, including taro beetles, in the 1950s to 1970s relied on the use of organochlorine insecticides (Jackson, 1992; Jackson and Klein, 2006), which led to the development of insect resistance and, as a result of their high persistence, to environmental contamination (Macfarlane, 1987a; Onwueme, 1999; Jackson and Klein, 2006). The organochlorine insecticides were subsequently banned and replaced by less persistent, but more toxic, carbamate and organophosphate insecticides, but because of their lower persistence these were less effective against soil-dwelling larvae (Jackson, 1992). More recent insecticides, such as insect growth regulators and neonicotinoid compounds, are more specific, particularly against early larval instars, but to be effective they must be applied before damage is visible in order to penetrate the soil (Jackson and Klein, 2006). Imidacloprid (trade name Confidor) and bifenthrin have been shown to be effective against taro beetles, giving marketable yields up to 90% (Lal, 2008).

Biological control

More recent research efforts have concentrated on finding effective biological control agents for taro beetles (Aloalii et al., 1993; Onwueme, 1999). Larval parasites are not effective as biocontrol control agents (Macfarlane, 1987a) and studies have mainly concentrated on the use of pathogens, e.g. the fungus Metarhizium anisopliae and the bacterium Paenibacillus popilliae (formerly Bacillus popilliae). Much of this research has taken place within the Taro Beetle Management (TBM) project (Lal, 2008).

Metarhizium anisopliae has shown some effectiveness against Papuana huebneri in the field, but very high levels of inoculum in the soil are necessary and the fungus takes 2–3 weeks to kill the beetle, during which time the beetle has caused damage (Theunis and Teuiara, 1998; McGlashan, 2006; Lal, 2008). It is difficult and costly for farmers to maintain stocks of the fungus, which has to be grown on, for example, rice grains, and applied to each planting hole as well as to likely breeding sites. Low-cost mass production methods are necessary to make M. anisopliae practical as a biocontrol agent against taro beetles (Macfarlane, 1987a; Lal, 2008; Tsatsia and Jackson, 2014).

In field studies in South Tarawa, Kiribati, in 1995-1996, the bacterium Paenibacillus popilliae type A1 was found to infect Papuana huebneri larvae for up to a year after application, indicating its potential as a biocontrol agent (Theunis and Teuriara, 1998).

Laboratory studies have shown increased mortality and symptoms of infection of Papuana huebneri following artificial infection of larvae and adults by Oryctes baculovirus (OBV, or Oryctes rhinoceros nudivirus), which has been successfully used as a biological control agent in several South Pacific Island nations against the Asian rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae). The practical implications of these findings for a future biological control strategy of taro beetle are discussed in Schuhbeck and Bokosou (2006).

Preliminary tests in the laboratory showed that adults of Papuana huebneri were susceptible to strain #326 of the nematode Steinernema glaseri (Theunis, 1998).

IPM

Reliance on insecticides is not considered to be a long-term solution for this very persistent pest because it may lead to the development of insecticide resistance (Lal, 2008). The best long-term solution for the management of taro beetles, and scarabs in general, is through integrated pest management (IPM) (Jackson and Glare, 1992; Jackson and Klein, 2006). The SPC/EU Taro Beetle Management (TBM) project, in Papua New Guinea, Fiji, Vanuatu, the Solomon Islands and Kiribati, ran from January 2002 to December 2007 with the aim of developing an integrated crop management package for taro to minimize damage caused by taro beetles (McGlashan, 2006; Lal, 2008).

The TBM project evaluated the biological control agents Metarhizium anisopliae and Oryctes virus, and a chemical pesticide system. Imidacloprid and bifenthrin, on their own or in combination, provided good control of taro beetles and resulted in marketable yields of taro corms of up to 95%. M. anisopliae was found to be a potentially useful biological control agent but did not give the required level of control when used alone, giving marketable yields of taro corms of 30%.  However, applications of imidacloprid at a very low dosage of 0.75 ml per litre of water at planting in combination with 10 g of M. anisopliae gave yields similar to those obtained using either of the two insecticides on their own. It was concluded that the two insecticides should be alternated to avoid resistance. A package of best practices for the management of taro beetles was developed and demonstrated to taro growers, focusing on methods of application and safety, correct usage rates, and frequency of insecticide applications (Lal, 2008).

Oryctes virus was found to be a potentially good biological control agent for taro beetles, but more work was required to produce pure cultures of the virus and to develop suitable methods for its transmission in the field. It was recommended that future work should focus on the practical use of sex pheromones as a component of an IPM approach to aid in dissemination of the virus.

Cultural practices used by farmers (e.g. plant extracts) could also be combined with modern pest control approaches to protect against taro beetles. There was also a need to evaluate the effectiveness of new insecticides with lower environmental impacts (Lal, 2008).

It has been recommended that an integrated crop management approach should be used to manage taro beetles, with a combination of cultural control (crop rotation, clean and soil-free planting material, destruction of breeding sites near farms), chemical control (using imidacloprid or bifenthrin), biological control (using M. anisopliae) and phytosanitary procedures. The use of chemicals alone was found to be effective and economic only in large commercial taro production where corms are produced for the urban or export market (Carmichael et al., 2008; TaroPest, 2015).

References

Top of page

Aloalii I, Masamdu R, Theunis W, Thistleton B, 1993. Prospects for biological control of taro beetles, Papuana spp. (Coleoptera: Scarabaeidae), in the South Pacific. [Proceedings of the Sustainable Taro Culture for the Pacific Conference; 1992 Sept 24–25; Honolulu, Hawaii], [ed. by Ferentinos L]. Honolulu, Hawaii, USA: University of Hawaii. 66-70. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-140-17.pdf

APPPC, 1987. Insect pests of economic significance affecting major crops of the countries in Asia and the Pacific region. Bangkok, Thailand: Regional Office for Asia and the Pacific region (RAPA). (Technical Document No. 135)

Biosecurity Australia, 2011. Review of import conditions for fresh taro corms. Canberra, Australia: Biosecurity Australia.216 pp.

Braidotti G, 2006. Fighting back against diseases and pest of taro. Partners in Research for Development, (Autumn), 6-7. https://www.aciar.gov.au/file/69126/download

Carmichael, A., Harding, R., Jackson, G., Kumar, S., Lal, S., Masamdu, R., Wright, J., Clarke, A., 2008. TaroPest: an illustrated guide to pests and diseases of taro in the South Pacific, [ed. by Carmichael, A., Harding, R., Jackson, G., Kumar, S., Lal, S., Masamdu, R., Wright, J., Clarke, A.]. Canberra, Australia: Australian Centre for International Agricultural Research (ACIAR).76 pp. https://www.aciar.gov.au/node/9506

Centre for Overseas Pest Research, 1978. Pest Control in tropical root crops. London, UK: Ministry of Overseas Development.235 pp. (PANS manual no. 4)

Dharmaraju E, 1982. The babai beetle problem in Kiribati. Alafua Agricultural Bulletin, 7(3):90-94

Food and Agriculture Organization, 1974. Report to the Government of the Gilbert and Ellice Islands Colony on a survey of insect pests of crops, based on the work of Peter D. Manser. Rome, Italy: FAO.v + 35 pp.

French BR, 2010. Food plants of Solomon Islands: a compendium. Part 1., Burnie, Tasmania, Australia: Food Plants International.160 pp. http://foodplantsinternational.com/free-resources-for-download/solomons/

GBIF, 2015. Global Biodiversity Information Facility, http://www.gbif.org/species

International Business Publications, 2010. Kiribati: Ecology & Nature Protection Handbook. Vol. 1. Strategic Information and Important Regulations, Washington DC, USA: International Business Publications.

Jackson, G. V. H., 1980. Diseases and pests of taro, Noumea, New Caledonia: South Pacific Commission.52 pp.

Jackson, T. A., Glare, T. R., 1992. Use of pathogens in scarab pest management, Andover, UK: Intercept.iii + 303 pp.

Jackson, T. A., Klein, M. G., 2006. Scarabs as pests: a continuing problem. Coleopterists Bulletin, 60(5(Suppl.)), 102-119. doi: 10.1649/0010-065X(2006)60[102:SAPACP]2.0.CO;2

Jackson, T.A., 1992. Scarabs – pests of the past or the future?. In: Use of pathogens in scarab pest management, [ed. by Jackson TA, Glare TR]. Andover, UK: Intercept Ltd. 1-10.

Jamieson, L. E., Chhagan, A., Redpath, S. P., Griffin, M. J., Rohan, C., Tunupopo, F., Tugaga, A., Connolly, P. G., Woolf, A. B., 2016. Development of a hot water disinfestation treatment for taro exported from the Pacific Islands. New Zealand Plant Protection, 69, 200-206. https://www.nzpps.org/nzpp_download.php?path=journal/69/nzpp_692000.pdf

Jamieson, L. E., Page-Weir, N. E. M., Wilkinson, R. T., Redpath, S. P., Hawthorne, A. J., Brown, S. D. J., Aalders, L. T., Tunupopo, F., Tugaga, A., To'omata, T., Shah, F., Armstrong, J. W., Woolf, A. B., 2018. Developing risk management treatments for taro from the Pacific Islands. New Zealand Plant Protection, 71, 81-92. https://journal.nzpps.org/index.php/nzpp/article/view/179 doi: 10.30843/nzpp.2018.71.179

Lal SN, 2008. Taro beetle management in Papua New Guinea and Fiji. Final project report. Noumea, New Caledonia: Secretariat of the Pacific Community.38 pp.

Macfarlane B, 1987. Papuana beetles. Noumea, New Caledonia: South Pacific Commission.4 pp. (Advisory Leaflet 21)

Macfarlane B, 1987. What’s in a name! – Fiji taro beetle re-identified. Information Circular, South Pacific Commission, (104), 1.

Masamdu R, 2001. Papuana huebneri huebneri (Fairmaire). EcoPort Foundation.http://ecoport.org/ep?Arthropod=19810

Masamdu, R., Simbiken, N., 2001. Effect of taro beetles on taro production in PNG. In: Food security for Papua New Guinea. Proceedings of the Papua New Guinea Food and Nutrition 2000 Conference, PNG University of Technology, Lae, Papua New Guinea, 26-30 June 2000,[ed. by Bourke, R. M., Allen, M. G., Salisbury, J. G.]. Canberra, Australia: Australian Centre for International Agricultural Research (ACIAR). 752-757.

McGlashan H, 2006. Battling the beetle. Partners in Research for Development, (Autumn), 8-9. https://www.aciar.gov.au/file/69126/download

Onwueme I, 1999. Taro cultivation in Asia and the Pacific, Bangkok, Thailand: Food and Agriculture Organization of the United Nations Regional Office for Asia and the Pacific.50 pp. http://www.fao.org/3/ac450e/ac450e00.htm (RAP Publication 1999/16)

Perry CH, 1977. The ecology and control of some taro pests in Papua New Guinea. In: Agriculture in the tropics, [ed. by Enyi BAC, Varghese T]. Port Moresby, Papua New Guinea: University of Papua New Guinea. 319-322.

Sandhu, G. S., Teaotai, R., 1992. National IPM programme of Kiribati. In: Integrated pest management in the Asia-Pacific region [Integrated pest management in the Asia-Pacific region], [ed. by Ooi, P. A. C., Lim, G. S., Ho, T. H., Manalo, P. L., Waage, J. K.]. Wallingford, UK: CAB International. 373-381.

Schuhbeck, A., Bokosou, J., 2006. The distribution of oryctes baculovirus in different species of Scarabaeidae on New Britain Island, Papua New Guinea. In: ACIAR Technical Reports Series [Pest and disease incursions: risks, threats and management in Papua New Guinea. Papers presented at the 2nd Papua New Guinea Plant Protection Conference, East New Britain Province, 8-10 November 2004], (No.62) [ed. by Price, T. V.]. Canberra, Australia: Australian Centre for International Agricultural Research (ACIAR). 184-191.

Singh, S. R., 1984. Fiji-taro beetle. Quarterly Newsletter, FAO Asia and Pacific Plant Protection Commission, 27(1/3), 6.

TaroPest, 2015. Taro beetles. Papuana spp. Bruce, ACT, Australia: Australian Centre for International Agricultural Research.http://www.ediblearoids.org/TaroPEST.aspx

Theunis W, Teuriara N, 1998. Biological control of Papuana huebneri (Coleoptera, Scarabaeidae) in Kiribati: field trials with Metarhizium anisopliae and Bacillus popilliae. Journal of South Pacific Agriculture, 5(1):46-51

Theunis, W., 1998. Susceptibility of the taro beetle, Papuana uninodis, to entomopathogenic nematodes. International Journal of Pest Management, 44(3), 139-143. doi: 10.1080/096708798228239

Thomas FR, 2002. Self-reliance in Kiribati: contrasting views of agricultural and fisheries production. The Geographical Journal, 168(2), 163-177.

Thomas FR, 2003. Kiribati: “some aspects of human ecology,” forty years later: Atoll Research Bulletin, 501, 40 pp. https://repository.si.edu/bitstream/handle/10088/5917/00501.pdf

Tsatsia H, Jackson G, 2014. Taro beetles (extension fact sheet 30). In: Fiji, Samoa, Solomon Islands & Tonga. 162 Extension Fact Sheets, Ministry and Agriculture and Livestock, Solomon Islands: http://issuu.com/terracircle/docs/extensionfs/74

Varin D, Vernier P, 1996. Dryland cultivation of taro, Colocasia esculenta, in New Caledonia. [The second taro symposium. Proceedings of an international meeting held at the Faculty of Agriculture, Cenderawasih University, Manokwari, Indonesia, 23–24 November 1994], [ed. by Jackson G, Wagih ME]. Indonesia and Papua New Guinea: Cenderawasih University and Papua New Guinea University of Technology. 67-73.

Distribution References

APPPC, 1987. Insect pests of economic significance affecting major crops of the countries in Asia and the Pacific region. In: Technical Document No. 135, Bangkok, Thailand: Regional Office for Asia and the Pacific region (RAPA).

CABI, Undated. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI

CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Dharmaraju E, 1982. The babai beetle problem in Kiribati. Alafua Agricultural Bulletin. 7 (3), 90-94.

Food and Agriculture Organization, 1974. Report to the Government of the Gilbert and Ellice Islands Colony on a survey of insect pests of crops, based on the work of Peter D. Manser. In: Report to the Government of the Gilbert and Ellice Islands Colony on a survey of insect pests of crops, based on the work of Peter D. Manser. Rome, Italy: FAO. v + 35 pp.

Jackson T A, Klein M G, 2006. Scarabs as pests: a continuing problem. Coleopterists Bulletin. 60 (5(Suppl.)), 102-119. DOI:10.1649/0010-065X(2006)60[102:SAPACP]2.0.CO;2

Macfarlane B, 1987. What’s in a name! – Fiji taro beetle re-identified. Information Circular, South Pacific Commission. 1.

Sandhu G S, Teaotai R, 1992. National IPM programme of Kiribati. In: Integrated pest management in the Asia-Pacific region. [Integrated pest management in the Asia-Pacific region.], [ed. by Ooi P A C, Lim G S, Ho T H, Manalo P L, Waage J K]. Wallingford, UK: CAB International. 373-381.

Schuhbeck A, Bokosou J, 2006. The distribution of oryctes baculovirus in different species of Scarabaeidae on New Britain Island, Papua New Guinea. In: ACIAR Technical Reports Series. [ed. by Price T V]. Canberra, Australia: Australian Centre for International Agricultural Research (ACIAR). 184-191.

Singh S R, 1984. Fiji-taro beetle. Quarterly Newsletter, FAO Asia and Pacific Plant Protection Commission. 27 (1/3), 6.

TaroPest, 2015. Taro beetles. Papuana spp., Bruce, ACT, Australia: Australian Centre for International Agricultural Research. http://www.ediblearoids.org/TaroPEST.aspx

Theunis W, Teuriara N, 1998. Biological control of Papuana huebneri (Coleoptera, Scarabaeidae) in Kiribati: field trials with Metarhizium anisopliae and Bacillus popilliae. Journal of South Pacific Agriculture. 5 (1), 46-51.

UK, Centre for Overseas Pest Research, 1978. Pest Control in tropical root crops. (PANS manual no. 4). In: Pest Control in tropical root crops. (PANS manual no. 4). London, UK: Ministry of Overseas Development. 235 pp.

Varin D, Vernier P, 1996. Dryland cultivation of taro, Colocasia esculenta, in New Caledonia. [The second taro symposium. Proceedings of an international meeting held at the Faculty of Agriculture, Cenderawasih University, Manokwari, Indonesia, 23–24 November 1994], [ed. by Jackson G, Wagih ME]. Indonesia and Papua New Guinea: Cenderawasih University and Papua New Guinea University of Technology. 67-73.

Principal Source

Top of page

Draft datasheet under review.

Contributors

Top of page

06/07/15 Original text by:

Angela Whittaker, Consultant, UK

Distribution Maps

Top of page
You can pan and zoom the map
Save map