Asiatic rhinoceros beetle

The Asiatic rhinoceros beetle, coconut rhinoceros beetle or coconut palm rhinoceros beetle,[2][3] (Oryctes rhinoceros) is a species of rhinoceros beetle of the family Scarabaeidae. O. rhinoceros attacks the developing fronds of raffia,[4] coconut, oil, and other palms in tropical Asia and a number of Pacific islands. Damaged fronds show typical triangular cuts.[Bed 1] The beetle kills the palms (particularly newly planted ones) when the growing point is destroyed during feeding.[5] They also infest dead trunk debris.[Bed 2]

Asiatic rhinoceros beetle
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Scarabaeidae
Subfamily: Dynastinae
Tribe: Oryctini
Genus: Oryctes
Species:
O. rhinoceros
Binomial name
Oryctes rhinoceros
Synonyms [1]

Scarabaeus rhinoceros Linnaeus, 1758

Biology

This large species has an average length of about 33 to 40 mm. Adults are dark brown to black in color with shiny dorsum. Head with a prominent horn. Male has longer horn than the female. Male is characterized by a rounded, shiny terminal abdominal segment whereas female has a relatively hairier 'tail'. There are two tubercles on the thoracic ridge.[6]

Eggs

Adult female lay yellowish-white oval eggs which are about 3 mm in diameter. Eggs are typically laid inside rotting vegetative matter. After one week, they swell and later hatch within 11 to 13 days.[6]

Larva

Grub stage undergo three instars before becoming a pupa. Grubs are yellowish-white where the third instar grow to 60 to 100 mm in length. Cranium is dark brown, with many round pits. There are minute setae on cranium. Thoracic spiracles are about 1.85 to 2.23 mm long. Respiratory plate consists with small, round to oval holes. Thoracic spiracles are larger than abdominal spiracles.[6]

Pupa

Pupa is yellowish-brown with about 50 mm in length. There are horn-shaped protuberances on the anterior surface.[6]

Economic importance

O. rhinoceros adults are nocturnal.[Bed 3]

In 1964, accidental introduction in some countries, and the perceived threat led to a special United Nations fund being established through the South Pacific Forum, with the goal of "eradication of the rhinoceros beetle and related insects in the South Pacific". Contributors to the fund were Australia, France, New Zealand, the United Kingdom, the United States of America, and Western Samoa.[7]

Control measures include the use of cultural methods, such as crop sanitation and the use of cover crops, pheromones, together with biological controls such as the manipulation of Metarhizium majus and M. anisopliae.[Bed 4][Bed 2] A nudivirus – the Oryctes rhinoceros nudivirus (OrNV) – has been very successful in the Pacific islands[Bed 5] and for 30 years the invasion was halted.[Mar 1] However, a new haplotype – CRB-G – has been invading the Pacific at a rate of about one new island every two years,[Mar 2] unaffected by OrNV control programs already in place because CRB-G is immune.[Mar 3]

The beetle is an invasive species in Hawaii, where it was found on December 23, 2013. It is believed to have been brought there in air cargo.[8] Following the beetle's impact in Hawaii, there are now concerns about the potential consequences to Australia should the beetle be detected there.[9] In June 2021, University of Queensland researcher Dr Kayvan Etebari and Central Queensland horticulturalist Neil Fisher both publicly expressed concerns about how close the species is to Australia and the threat it poses to the country's emerging date industry, ornamental palms and coconut oil industries.[9][10] Fisher said the beetle's impact to agriculture and horticulture in Hawaii has raised "red flags" in Australia.[9] Etebari said it was important for Australia to assist its neighboring countries in controlling the beetle for both economic and humanitarian reasons due to the threat it poses to livelihoods.[9][10]

Damage

In 1885, heavy infestations on coconut has been observed from Malaysia. Then in 1911, they appeared in Myanmar. In early 1900s, it was observed from potted rubber seedlings from Sri Lanka which was later introduced to Upolu island in Western Samoa in 1909. Adults and grubs usually attack coconut and oil palm cultivations, where they are considered as a major pests. Adults feed on crown region of the palms. Then they bore through petiole bases into the central unopened leaves. This results tissue maceration and dieback. Presence of the animal can be visible due to fibrous frass found inside and at the entrance to the feeding hole. Most often fronds became wedge-shaped gaps or characteristic V-shaped cuts to fronds.[6]

Selected host plants

Control

Adults can be removed by hand picking or other mechanical method. In biological control, they can be eradicated by using predators, pathogens and scoliid parasitoids. Apart from that, a male-produced aggregation pheromone, ethyl 4-methyloctanoate (E4-MO) is an effective method to control the adults. Under cultural control, breeding sites of the adult can be destroyed, as well as usage of cover crops, and use of a hooked piece of wire is effective. Meanwhile, several insecticides such as gamma-BHC, cypermethrin, lambda cyhalothrin, and naphthalene can be used.

Pathogens
Metarhizium majus infected O. rhinoceros larvae at various stages of insect disease.

The most widely used control pathogen appears to be Metarhizium majus, but entomopathogenic viruses have also been deployed.

Predators
  • Alaus farinosus
  • Alaus montravelii
  • Alaus podargus
  • Alaus speciosus
  • Brachinus stenoderus
  • Catascopus facialis
  • Hololepta marginipunctata
  • Hololepta quadridentata
  • Lanelater bifoveatus
  • Lanelater fuscipes
  • Mecodema spinifer
  • Neochryopus savagei
  • Ochyropus gigas
  • Oxylobus punctatosulcatus,
  • Pachylister chinensis
  • Pheropsophus consimilis
  • Pheropsophus lissoderus
  • Pheropsophus occipitalis
  • Pheropsophus sobrinus
  • Pheropsophus stenoderus
  • Placodes ebenenus
  • Plaesius javanus
  • Platymeris laevicollis
  • Santalus parallelus
  • Scarites dubiosus
  • Scarites madagascariensis

Parasitoids

See also

References
  1. Lars Wallin (February 14, 2001). "Catalogue of type specimens. 4. Linnaean specimens" (PDF). Uppsala University. Retrieved August 28, 2010.
  2. "GISD". Iucngisd.org. Retrieved 16 March 2022.
  3. "Entity Display : Oryctes rhinoceros". Ecoport.org. Retrieved 16 March 2022.
  4. "Raphia farinifera (PROTA)". Uses.plantnet-project.org.
  5. "Coconut Rhinoceros Beetle : Pests and Diseases of American Samoa Number 8" (PDF). Ctahr.hawaii.edu. Retrieved 16 March 2022.
  6. "Oryctes rhinoceros (coconut rhinoceros beetle)". Cabi.org. Retrieved 2021-07-26.
  7. "Agreement between the Government of Australia and the United Nations Special Fund concerning Assistance from the Special Fund for a Project of Research on the Control of the Coconut Rhinoceros Beetle ATS 18 of 1964”. Australasian Legal Information Institute, Australian Treaties Library. Retrieved on 15 April 2017.
  8. Lin, Sara (24 January 2015). "Hawaii hopes to fend off invasion by coconut rhinoceros beetle". LA Times. Retrieved 28 January 2015.
  9. Stünzner, Inga (17 June 2021). "Destructive coconut rhinoceros beetle a 'stone's throw' from Australia as it spreads through Pacific". ABC News. Australian Broadcasting Corporation. Retrieved 17 June 2021.
  10. "'Unshackled' palm-destroying beetles could soon invade Australia". UQ News. The University of Queensland. 17 June 2021. Retrieved 17 June 2021.
  1. p. 127, §1. Introduction
    "The invasive phase of the beetle was brought under control by the discovery and distribution of a viral biocontrol agent, Oryctes rhinoceros nudivirus (OrNV; previously known as Rhabdiovirus oryctes and Baculovirus oryctes). OrNV is currently present and causes persistent population suppression on many of the CRB infested Pacific Islands (Bedford, 2013b; Huger, 2005).
    Virus introduction into affected Pacific Island countries and territories suppressed and weakened the CRB populations such that its spread into the Pacific islands ceased and for 30 years there was no further expansion of the range of CRB (Secretariat of the Pacific Community, 2015)."
  2. p. 133, §4, "...Over the past decade, CRB-G has spread to uninfested islands at a rate of about one new island every two years."
  3. p. 133, §4. Conclusion
    "The CRB-G haplotype identified here is genetically distinct from other CRB populations already established in the Pacific region and is highly damaging to palms. The evidence provided demonstrates CRB-G is not appreciably affected by the OrNV isolates commonly used for biocontrol management of other CRB populations."
  1. p. 355, "The damaged frongs show characteristic V- or wedge-shaped cuts as they unfold, reducing the photosynthetic area (Supplemental Figure 7).
  2. p. 355, "Malaysia ...By 12 months, infection levels for treatments were approximately 70%, mostly for third-instar larvae, and 52% for control heaps (81). ... These results indicated that M. anisopliae is best applied early, i.e., 6 to 8 months after chipping of the trunks; the water carries the spores deeper into the breeding sites and aids their germination, and the mycosis replenishes the spores (78). Without spore applications, two-year-old shredded rotting coconut trunk debris, with 0–2% M. anisopliae infections and cover crop overgrowth, could contain substantial numbers of larvae (96)."
  3. p. 355, "Studying the biology of O. rhinoceros adults is difficult (106). They are cryptic, hidden in their feeding holes or in breeding sites, and fly only at night."
  4. p. 354, "...four such Malaysian isolates killed all third-instar larvae after 14 days (78, 79)."
  5. p. 357, "MANAGEMENT BY ORYCTES NUDIVIRUS OrNV is a key agent for Oryctes management in areas where it is not endemic, necessitating laboratory-based work since 1980, interconnected with fieldwork, to extend our knowledge of this pathogen."
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