Coleoptera (beetles) of the British Indian Ocean Territory

Adoretus versutus, commonly known as rose beetle,^[1] is a species of shining leaf chafer found in Afro-Oriental tropics.

Etymology

Common names of the beetle includes: Indian rose beetle, leaf chafer beetle, rRose beetle, Fijian root grub, and Fijian cane root grub.^[2]

Distribution

It is native to Oriental regions and can be found in many Asian countries including: India, Andaman and Nicobar islands, Pakistan, Sri Lanka, and Indonesia. It is also distributed in African islands: Madagascar, Mauritius, St. Helena, Seychelles, Fiji, and Oceanian islands: Samoa, Tonga, Wallis Islands, Cook Islands. Meanwhile, the species has introduced to many countries where they became major pests due to absence of natural predators.^[2]

It is also introduced to Vanuatu where it became a serious pest due to absence of predators.^[3] It is also found in New Caledonia.^[4]

Biology

Lifecycle usually completed in three months. Female known to lay eggs in soil during early part of the monsoon season between May to August. Eggs hatch after 8 to 14 days in soil.^[5] Larvae can be seen in around a week and started to feed on roots. During drought periods, larvae move deeper in the soil where the come closer to the surface during wet periods. Pupation completed before the onset of next monsoon. Adults emerge after rainy showers.^[2]

Larva

Grubs are whitish translucent in color. The resting posture is C-shaped. Third instar is about 20-25 mm in length. Head reddish brown in color. The last abdominal segment swollen and dark particularly due to the soil ingestion. Spiracles creamy white with 9 pairs in which one pair prothoeracic and eight pairs abdominal segments.^[2][5]

Pupa

Pupa yellowish brown where they become much darker in final pupal stages. Full grown pupa is about 16 mm in length.^[2]

Adult

Adult beetle has large dark eyes. Body reddish chestnut in color with average length of 12 to 14 mm in length. However, male is smaller than female.^[5] Body broader and convex with shiny underside. Scutellum short. Lamellate antennae are brownish, with ten-segments. Last three antennomeres expanded into a plate like structure. Pronotum dark and less densely punctate in the mid region. Clypeus and frons darker. Labrum and labium hairy. There are acute teeth in tibia of first leg pair which helps during burrowing in sand. Elytra brownish with metallic sheen, sclerotized, and punctate. There are fine bristles in elytra, pronotum and head.^[2] Female has broader body which is more convex.^[6]

Economic importance

A polyphagous pest, it is one of the major pest in cocoa plantations and rose cultivations in Vanuatu and other countries.^[3][7] It also attack shade trees, and ornamentals in Uganda where the outbreak of adults show defoliation.^[2] Grubs also attack the roots of wild turmeric.^[8]

In Fiji, the larvae can be destroyed by an entomopoxvirus.^[9][10]

host plants

References

Diocalandra frumenti, commonly known as the palm weevil borer, the lesser coconut weevil,^[3] or four-spotted coconut weevil,^[4] is a species of weevil in the family Curculionidae. It occurs in Africa, Southern Asia and Northern Australia, and is a pest of coconut and other palm trees.

Distribution

Diocalandra frumenti is found in Somalia, Tanzania, Madagascar, the Seychelles, Mauritius, India, Sri Lanka, Bangladesh, Myanmar, Malaysia, Singapore, Indonesia, the Philippines, Japan, Taiwan, Papua New Guinea, various Pacific island groups and Australia. It has also been recorded in the Canary Islands.^[5][6] Although infesting a number of species of palm, it is a major pest of coconut (Cocos nucifera), oil palm (Elaeis guineensis), Canary Island date palm (Phoenix canariensis), date palm (Phoenix dactylifera), California fan palm (Washingtonia filifera) and Mexican fan palm (Washingtonia robusta).^[7]

Life cycle

The adult Diocalandra frumenti is about 7 mm (0.3 in) long. It is a glossy black colour with four large rusty-brown or blackish-brown coloured spots on the elytra (wing covers}. The female lays eggs in crevices in the stems of palms which hatch in about a week. The larvae bore into the stem where they form extensive galleries. After eight to ten weeks they pupate, the adult emerging from the pupal case about eleven days later.^[8]

Damage

Eggs may be laid among the flowers, in cracks in the leaf or flower stalks, or near the base of the stem just above the adventitious roots. As the larvae bore deeper into the palm, a gummy exudate forms in the entry hole. The galleries can damage any part of the palm including the roots. Leaves may turn yellow and fruit may drop off, and severe infestations may cause the plant to die.^[8] It has been found that the males emit a pheromone which attract females, and this may make it possible to trap the insects, which are strong fliers, and reduce the level of infestation. The weevil has a number of natural enemies including a parasite Spathius apicalis, a predatory fly Chrysophilus ferruginosus and a predatory beetle Plaesius javanus.^[9]

References

Lithocharis nigriceps is a species of beetle belonging to the family Staphylinidae.^[1]

It has cosmopolitan distribution.^[1]

References

Osorius is a genus of unmargined rove beetles in the family Staphylinidae. There are about nine described species in Osorius.^[1][2][3][4]

Species

• Osorius brevicornis Notman, 1920
• Osorius brevipennis Notman, 1925
• Osorius difficilis Notman, 1925
• Osorius latipes (Gravenhorst, 1806)
• Osorius parcus Sharp, 1887
• Osorius parviceps Notman, 1925
• Osorius planifrons LeConte, 1877
• Osorius politus LeConte, 1877
• Osorius variolatus Notman, 1925

References

Pentarthrum is a genus of beetle in family Curculionidae. It contains about 70 species of mainly tropical distribution.^[1]

Partial list of species

• Pentarthrum angustissimum Wollaston, 1873
• Pentarthrum blackburni Sharp, 1878
• Pentarthrum halodorum Perkins, 1926
• Pentarthrum huttoni Wollaston, 1854
• Pentarthrum obscurum Sharp, 1878

References

Xyleborus perforans, commonly known as island pinhole borer, is a species of weevil native in the Oriental region through to Australia but shows a cosmopolitan distribution due to introduction to many parts of the world.^[1]

Distribution

The native range of the species include: Bangladesh, Cambodia, China, Hong Kong, India, Andaman and Nicobar Islands, Indonesia (Java, Maluku Islands, Sulawesi, Sumatra), Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan, Thailand, Vietnam, Papua New Guinea and Australia.^[2]

It is introduced to many African, European and American countries particularly through timber and wood commodities. This exotic range includes: Burundi, Cabo Verde, Cameroon, Comoros, Democratic Republic of the Congo, Republic of the Congo, Côte d'Ivoire, Gabon, Ghana. Kenya, Madagascar, Malawi, Mauritius, Nigeria, Réunion, Rwanda, São Tomé and Príncipe, Seychelles, Sierra Leone, Somalia, Tanzania, Uganda, Cocos Islands, Ryukyu Islands, Maldives, Portugal, Spain, Canada, British Columbia, United States, Hawaii, American Samoa, Christmas Island, Cook Islands, Micronesia, Fiji, French Polynesia, Guam, Kiribati, Marshall Islands, New Caledonia, Niue, Northern Mariana Islands, Palau, Samoa, Solomon Islands, Tonga, and Vanuatu.^[2]

Description

Body length of the female ranges from 2.1 to 2.5 mm. Frons convex, and the entire surface is minutely reticulate with faint, shallow punctures. Pronotum sides are moderately arcuate whereas the anterior margin is broadly rounded, without serrations. Elytral apex is narrowly rounded. Elytral declivity is steep, and convex. There is a row of 4 to 5 small, acute granules found in elytral interspaces 1 and 3.^[3]

Biology & control

A highly polyphagous species, it is known from diverse array of host plants. Due to being a secondary borer, it is considered as a high-risk quarantine pest. They show inbreeding, where the males usually mating with their sisters within the parental gallery system before dispersal. It is particularly common in disturbed areas and flies mainly around dusk, and can be attracted to light in large numbers easily. Adults normally attacks stressed or recently felled trees, newly sawn timber, fire-damaged trees, and salvaged logs. Sometimes, they attack living trees particularly through injuries or diseased areas. However, there is no any attack observed in small shoots and twigs.^[4][5]

The gallery system consists of branching tunnels, without enlargements, and penetrate deeply into the wood. During severe attacks, the tunnels ranges from different broods which are intersect withothers. These tunnels are usually in one transverse plane and rarely in vertical galleries. The surface galleries also have been observed at the cambial level. The first eggs brood appear when the tunnel length is from 3–8 cm. Then the emerging larvae develop and pupate within the same gallery system. Both parent female and the larvae feed on the ambrosia fungus such as Ambrosiella which are growing on the walls of the galleries. The fungus is transmitted by the female in a mycangium. Duration of the egg stage is about 4 days, and the larval stage is about 7 to 9 days. Pupal stage is 4 days, where the total duration from egg to teneral adult is about 16 to 18 days. The first females of the new generation extend the gallery system, and begin to lay eggs before the parental female has died. Therefore, overlapping generations is common within a single cane stem.^[4]

Adults can be controlled naturally by the parasite Phymastichus xylebori and other natural predators such as lizards, clerid beetles and ants as they attempt to bore into the host tree. Immature stages are susceptible for both predators and parasitoids.^[4]

Host plants

• Acacia mangium
• Agathis macrophylla
• Albizia zygia
• Anacardium occidentale
• Annona squamosa
• Araucaria cunninghamii
• Artocarpus heterophyllus
• Bauhinia variegata
• Bombax ceiba
• Boswellia serrata
• Carica papaya
• Cinnamomum verum
• Citrus
• Cocos nucifera
• Diospyros suaveolens
• Dryobalanops aromatica
• Eucalyptus
• Ficus
• Gonystylus bancanus
• Hevea brasiliensis
• Leucaena leucocephala
• Macadamia integrifolia
• Mangifera indica
• Parkia bicolor
• Persea americana
• Punica granatum
• Rhizophora mangle
• Rhizophora mucronata
• Saccharum officinarum
• Shorea robusta
• Theobroma cacao
• Toona ciliata

References