The epizootiology of the baculovirus of the coconut palm rhinoceros beetle (Oryctes rhinoceros) in Tonga

The incidence and distribution of the baculovirus of the coconut palm rhinoceros beetle was determined in Tongatapu, Tonga, 7 years after being first introduced. Surveys showed the virus to be spread throughout the beetle population, affecting 14.6% of breeding sites and over 84% of all adult beetles taken. Counts of damaged palms and of breeding site occupancy indicated that beetle numbers had remained at low levels. It appears that the virus has the potential for long-term control of beetle populations in these habitats.     

Sex ratio and female sexual status of the coconut pest, Oryctes monoceros (Coleoptera: Dynastidae), differ in feeding galleries and pheromone-baited traps

Oryctes monoceros is a serious coconut pest, causing up to 40% damage in tropical Africa. Synthetic aggregation pheromone, ethyl 4-methyloctanoate, has been used to lure adults to traps. Traps with pheromone plus decaying palm material captured a high proportion of males. This raises the question whether individuals, which damage palms are receptive to the pheromone. We studied the sex ratio of the insects feeding on coconuts and those attracted to pheromone traps. Sixty two percent of adults from feeding galleries on living coconut palms were females. Pheromone with rotting palm material lured 43% females. To investigate the reasons for this difference, we compared the reproductive system of females lured to the odour traps or feeding in coconut galleries, or present in old rotting stems. Ninety six percent of the females trapped by pheromone had mated, and were sexually mature. In the galleries on living palms, 46% of females were immature, and 24% had not mated. In old rotting stems where eggs are laid and larvae develop, a mixture of 52% mated and 48% virgin females was found. Therefore, the pheromone together with the odour of rotting coconut stems signals a reproduction site to beetles, particularly mature females. In practice, the pheromone-baited traps will help in reducing the dissemination of gravid females, but will not affect directly the numbers of immature ones attacking palms. Our results show that when using pheromones for monitoring or controlling insects, the physiological status of the insects may have unexpected effects on the outcome.     

Phytophagous insects associated with cadang-cadang infected and healthy coconut palms in South-eastern Luzon, Philippines

Abstract. 1. The most common phytophagous insects associated (as adults) with the leaves of coconut palms in the Southeastern part of Luzon have been identified as part of a study on the natural method of spread of cadangcadang disease. Sixty-three species, of which at least twenty individuals were caught alive or with sticky boards, and five colony-forming Homoptera are listed. The sixty-three species belonged to the orders of Orthoptera (two species), Coleoptera (eight species), Hemiptera (one species) and Homoptera (fifty-two species, mainly Cicadellidae and Derbidae).
2. Three beetles ( Oryctes rhinoceros, Plesispa reichei and Hemipeplus sp.) and a lace bug ( Stephanitis typicus ) were found to be significantly more abundant in areas with a high incidence of cadangcadang disease. O.rhinoceros and P.reichei were also significantly more common on old palms (which are predisposed to the disease), and more abundant on cadang-cadang infected than on neighbouring healthy palms. Hemipeplus sp. apparently feeds by scraping the cuticle layer of the youngest fronds.     

Social media posts suggest that coconut rhinoceros beetle has established in the Western hemisphere

The coconut rhinoceros beetle (CRB: Oryctes rhinoceros L.) is one of the most damaging pests of coconut and oil palms in the Asia/Pacific region but has not been reported from the Western Hemisphere. Here, we report a possible establishment of CRB in Nayarit, Mexico, based on an analysis of social media reports and photographs indicating the presence of the beetle and the distinctive v-shaped notches in palm fronds caused by the beetle feeding. CRB populations are destructive once established, therefore, urgent actions are required to contain the pest and prevent damage to coconut and oil palm in the Americas.     

Ecology of baculovirus-infected and healthy adults of Oryctes rhinoceros (Coleoptera: Scarabaeidae) on coconut palms in the Philippines

Abstract.

• 1 Males and females of Oryctes rhinoceros (L.), a serious pest of coconut palms, congregate in decaying coconut trunks to mate, oviposit and prepare the wood for the young larvae. A baculovirus disease is often transmitted from beetle to beetle in this environment and transmission to and from larvae probably also occurs.
• 2 Young beetles are mainly found feeding on palms, where they also frequently contract the virus disease, presumably through mating with diseased partners.
• 3 Monitoring beetle populations in the Philippines with attractant traps and by collections from palms showed seasonal fluctuations which were often inversely correlated with the incidence of the virus disease. Disease prevalence matched closely the proportion of females in the population. Possible explanations for this correlation and for the seasonality of the disease prevalence are outlined.

     

The Oryctes virus: its detection, identification, and implementation in biological control of the coconut palm rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae)

In view of the increasing and devastating damage by rhinoceros beetle (Oryctes rhinoceros) to coconut palms in the middle of last century, many efforts were made to find an efficient natural control factor against this pest, which could not be controlled by pesticides. The basic procedures of these monitoring programmes are outlined together with the final detection of a virus disease in oil palm estates in Malaysia in 1963. In extensive laboratory studies, the virus was isolated and identified as the first non-occluded, rod-shaped insect virus, morphologically resembling the baculoviruses. Infection experiments clarified the pathology, histopathology, and virulence of the virus and demonstrated that the virus was extremely virulent to larvae after peroral application. These findings encouraged the first pilot release of virus in 1967 in coconut plantations of Western Samoa where breeding sites were contaminated with virus. Surprisingly, the virus became established in the Samoan rhinoceros beetle populations and spread autonomously throughout the Western Samoan islands. As a consequence, there was a drastic decline of the beetle populations followed by a conspicuous recovery of the badly damaged coconut stands. This unexpected phenomenon could only be explained after it was shown that the adult beetle itself is a very active virus vector and thus was responsible for the efficient autodissemination of the virus. The functioning of the beetle as a 'flying virus factory' is due to the unique cytopathic process developing in the midgut after peroral virus infection. Pathological details of this process are presented. Because of the long-term persistence of the virus in the populations, rhinoceros beetle control is maintained. Incorporation of virus into integrated control measures and successful virus releases in many other countries are recorded.     

Detection of coconut cadang-cadang viroid-like sequences in oil and coconut palm and other monocotyledons in the south-west Pacific

Fractionation, electroblotting and molecular hybridisation of nucleic acids extracted from tissue of African oil palm and coconut palm and some other monocotyledonous species, collected in several areas of the south-west Pacific region, demonstrated the presence of small nucleic acids with nucleotide sequences and secondary structure similar to coconut cadang-cadang viroid (CCCVd). The oil palms which contained CCCVd-related molecules showed orange leaf spots resembling those described for oil palm naturally infected with CCCVd in the Philippines, and also characteristic of a condition known as "genetic orange spotting" (GOS). We provide preliminary evidence that GOS is an infectious disorder caused by a viroid. The coconut palms did not show symptoms typical of cadang-cadang disease, but sometimes were chlorotic, stunted, or had a reduced yield. The possibility that the isolates represent variants of CCCVd is discussed. The data suggest that viroids with nucleotide sequences similar to CCCVd occur widely in palms and other monocotyledons outside the Philippines.     

The incidence and use of Oryctes virus for control of rhinoceros beetle in oil palm plantations in Malaysia

The rhinoceros beetle, Oryctes rhinoceros, has emerged as a serious pest of oil palm since the prohibition of burning as a method for maintaining estate hygiene in the 1990s. The abundance of beetles is surprising given that the Malay peninsula was the site of first discovery of the Oryctes virus, which has been used to effect good as a biological control agent in other regions. A survey of adult beetles was carried out throughout Malaysia using pheromone traps. Captured beetles were examined for presence of virus using both visual/microscopic examination and PCR detection methods. The survey indicated that Oryctes virus was common in Malaysia among the adult beetles. Viral DNA analysis was carried out after restriction with HindIII enzyme and indicated at least three distinct viral genotypes. Bioassays were used to compare the viral strains and demonstrate that one strain (type B) is the most virulent against both larvae and adults of the beetle. Virus type B has been cultured and released into healthy populations where another strain (type A) forms the natural background. Capture and examination of beetles from the release site and surrounding area has shown that the spread and persistence of the applied virus strain is accompanied by a reduction in palm frond damage.     

Prospects of using Metarhizium anisopliae to check the breeding of insect pest, Oryctes rhinoceros L. in coconut leaf vermicomposting sites

During vermicomposting of coconut leaves by the earthworm Eudrilus sp., Oryctes rhinoceros L. (rhinoceros beetle), an insect pest of palms, was found to breed in the decomposing organic material. Metarhizium anisopliae var. major was tried as a biocontrol agent for management of this pest. The effect of pathogen at spore loads of 10(3), 10(4) and 10(5) per 10 g of substrate was tested in laboratory on Eudrilus sp. kept with O. rhinoceros grubs and on Eudrilus sp. alone for the pathogenic capability of the fungus on the pest and its possible toxicity towards the vermin. The efficacy of the entomopathogen was also tested in the field in vermicomposting tanks. In laboratory bioassay, 100% mycosis of O. rhinoceros grubs could be obtained while the entomopathogen had no toxic effect on the earthworms. There was a positive change in the number and weight of the earthworms on treatment with M. anisopliae. In the field, application of M. anisopliae reduced O. rhinoceros grubs in the vermicomposting tanks upto an extent of 72%. In conclusion, M. anisopliae could effectively control O. rhinoceros in vermicomposting sites and was non-hazardous to the vermicomposting process as well as the Eudrilus sp.     

Demography of the vegetable ivory palm Phytelephas seemannii in Colombia, and the impact of seed harvesting

1. The demography of the vegetable ivory palm Phytelephas seemannii was studied on the Pacific coast of Colombia and a female-based matrix model was used to determine the proportion of seed that can be sustainably harvested from the population.
2. The density of the palm stands ranged from 240 to 420 adult palms ha⁻¹. The sex ratio was 1:1 and palms of both sexes produced leaves at the same rate. Seedlings produced 1·2 leaves per year on average, juveniles 1·8, and adults 6·1–7·4.
3. Adult females had fewer leaves than males (18·5 vs. 21·3 on average). Leaves of females lasted about 2·7 years in the crown, those of males about 3·2 years.
4. Stems creep on the ground, growing at the apex and often dying behind, the extant portion not always reflecting the palm's total age. The longest stem of a female palm in the study plots was 2·5 m, corresponding to an 'extant' age of 85 years; the longest stem recorded was that of a male (outside the plots) 10·5 m long, corresponding to an 'extant' age of 184 years. These figures reflect differences in growth habit, not in longevity.
5. Reproduction began at about 24 years, when the palm still lacked an above-ground stem.
6. The population growth rate λ was 1·059, and was most sensitive to changes in survival of juveniles and adults, and relatively insensitive to changes in fecundity and growth.
7. River channel migration is the most important cause of adult mortality. Phytelephas seemannii is apparently an efficient colonizer of the understorey in the late phases of riverine forest succession.
8. The population can tolerate a harvest intensity of 86% of all seeds before λ decreases to the equilibrium level of 1·00. Monitoring of the populations under intensive harvesting is required.     

Microhabitat specialization in a species-rich palm community in Amazonian Ecuador

1 Relationships between microhabitat variables (altitude, inclination, topographic position, drainage, canopy height) and the distribution and abundance of palms and palm-like plants in 50 ha of old-growth terra firme rain forest in the Yasuní National Park, lowland Amazonian Ecuador, were examined using 118 20 × 20 m plots laid out in a stratified random design.
2 If microhabitat niche differentiation is important for maintaining the species richness of the community, then (i) the distribution of the palms will be strongly influenced by microhabitat heterogeneity and (ii) palms of similar growth form will show antagonistic microhabitat relationships.
3 Mantel and cluster analyses showed that palm species distributions were strongly structured by topography. The main difference in species composition was between plots in the bottomland and plots on the upper slopes and hill tops.
4 Logistic and logit analyses showed that 20 of the 31 palm and palm-like taxa analysed had distributions that were significantly related to the microhabitat variables measured, mainly to topography but also to drainage and canopy height.
5 Spatial autocorrelation in the overall community structure was not explained by the microhabitat variables. Analyses of distributions or abundances of single species showed neighbourhood effects for seven taxa.
6 Antagonistic patterns of microhabitat preferences were recognizable among some species pairs of small palms, medium-sized palms and palm-like plants, but not among canopy palms.
7 It is concluded that microhabitat specialization is an important factor in maintaining the diversity of this palm community, while mass effects might also be important.     

The effect of re-release of Oryctes rhinoceros baculovirus in the biological control of rhinoceros beetles in Western Samoa

The Rhinoceros Beetle Project in Western Samoa has developed and successfully applied biological methods to control the rhinoceros beetle, a serious pest of coconut palms, by using two specific pathogens, a baculovirus (Family Baculoviridae), and an entomopathogenic fungus, Metarhizium anisopliae. The application of virus particularly has markedly suppressed the beetle population and helped revive the copra industry. The virus disease had established itself in the wild beetle population several years after its introduction at a level between 30 and 50%. At the same time an increase in beetle numbers and damage to palm trees was experienced. Therefore, a continuous release of virus into beetle-infested areas was proposed. It was argued that, considering the relatively high level of “natural” virus incidence, further releases of virus into the population would be futile. In a combined research and control program, virus was again re-released into the wild beetle population which was already virus infected. The results show that through re-release the virus level can be raised and the number of beetles and consequently the damage can be reduced. The techniques of the control methods are described. The virus release is very easy and cheap; it requires no chemicals, no special equipment, and it is particularly recommended in situations where breeding places are inaccessible or other methods such as plantation sanitation are either impossible or economically impractical. Above all, the methods are absolutely safe from the standpoint of environmental protection.     

Zophiuma lobulata (Hemiptera: Lophopidae) causes Finschhafen disorder of coconut and oil palms

Finschhafen disorder (FD) affects coconut and oil palms in Papua New Guinea (PNG). It is characterised by yellow‐bronzing of fronds which begins at the tips and progresses towards the petiole. Although the planthopper Zophiuma lobulata (Hemiptera: Lophopidae) has been posited as a cause of FD, the basis of the relationship has not been established. Studies conducted previously on FD predate the availability of DNA‐based techniques to test for the involvement of plant pathogens such as phytoplasmas that cause yellows‐type diseases in many plant taxa and are transmitted by the order of insects to which Z. lobulata belongs. In this study, polymerase chain reaction (PCR) assays found no evidence of phytoplasmas or bacteria‐like organisms (BLOs) in tissues of coconut and oil palm symptomatic for FD and from Z. lobulata feeding on these plants. Further studies involved releasing Z. lobulata adults and nymphs onto caged, potted coconut and oil palms and onto palm fronds enclosed in mesh sleeves. In both experiments, chlorotic symptoms on the palms were observed in the presence of Z. lobulata. Insect‐free control palms did not exhibit chlorotic symptoms of FD. In the frond sleeve experiment, only the fronds where Z. lobulata fed developed chlorosis indicating that the disorder is not systemic. Unlike most yellows‐type diseases associated with Hemiptera, this study indicates that FD is because of a direct feeding effect on palms by Z. lobulata rather than transmission of a pathogen.     

Introducing Baculovirus oryctes Huger into Oryctes monoceros Oliv. populations in Tanzania

A follow-up of a Baculovirus oryctes release into the population of Oryctes monoceros in coconut plantations in Tanzania has been made to clarify important points which were not fully considered in an earlier publication. The low recovery of virus-infected field-collected beetles (29%) suggested that the release of B. oryctes virus was not a suitable method for the control of O. monoceros. The relatively dry conditions in the coconut growing areas were partly contributory since the virus is non-occluded. No significant and sustainable reduction in frond damage was obtained after the virus had established itself in the natural O. monoceros population. The status of O. monoceros as a serious pest of coconut is also revised since the beetle affects young plantations more than older plantations and control methods can be directed at picking up feeding insects by hooking and disposal of breeding sites.     

Giant rhinoceros beetle Golofa claviger (Linnaeus) (Coleoptera: Melolonthidae: Dynastini) is damaging North Brazilian oil palm plantations

The oil palm is an economically important crop cultivated in the North of Brazil. Damage caused by insects is one of the main causes of reduced productivity for the oil palm. Before this research, only the beetles of the family Curculionidae were considered to be oil palm pests in Brazil. However, for the first time, we report on the damage caused by a giant rhinoceros beetle to oil palm plantations in Pará, Brazil. The beetle was identified as Golofa claviger (Linnaeus, 1771), which has a single record in Brazil (Pará) but is widely distributed in South America. The species occurs in an unprecedentedly high abundance of local specimens. The attacks are concentrated on the central cluster of young palms. Feeding behavior is identified as the main cause of the damage as the beetles use their mouthparts to rip the plant tissues, causing wedge-shaped cuts on young fronds that have not yet unfurled. After an attack, the leaflets of the unfurled fronds are partially destroyed.     

Forest fragmentation effects on palm diversity in central Amazonia

1 The effects of fragmentation on quantitative measures of floristic diversity in a palm community were examined in the Biological Dynamics of Forest Fragments study area in central Amazonia. Three 1-ha, three 10-ha, two 100-ha and three continuous forest reserves, distributed among three sites, were surveyed. In each reserve, 10 20 × 20 m plots were sampled, resulting in a total of 110 plots representing 4.4 sampled hectares.
2 The taxon composition of this palm community was dominated by stemmed, understorey palms. A total of 23 225 individuals from 36 taxa was recorded; five of the taxa were not sampled in continuous forest.
3 Taxa richness did not vary across reserve size or sites unless taxa not sampled in the continuous forest were removed from the analysis. Smaller forest fragments then harboured fewer taxa in the seedling stage than large forest fragments or continuous forest, despite the short time since isolation (10–15 years). There was a significant effect of location on the number of taxa per plot for all life stages, but only seedling and total were significantly affected by reserve size.
4 Reserve size did not affect the Shannon and Evenness indices. Reserves of similar sizes were floristically more similar than reserves of very different sizes.
5 Palms are important for the structure and composition of the forest. Their conservation may require the establishment of a number of large reserves.     

The infectivity of Metarhizium anisopliae to two insect pests of coconuts

Papua New Guinea isolates of Metarhizium anisopliae from the rhinoceros beetles, Scapanes australis and Oryctes rhinoceros; the black palm weevil, Rhynchophorus bilineatus (Coleoptera); and three other insect orders (Hemiptera, Lepidoptera, and Dermaptera) were all short-spored (M. anisopliae var. anisopliae). Isolates from Scapanes were also pathogenic to Rhynchophorus and Oryctes. When a Scapanes isolate was grown on brown rice and released into the frond axils of young palms, 32% of dead Scapanes adults collected during the following 48 weeks were infected compared to 1% in the control nonrelease palms. Some infection of Rhynchophorus also occurred. Infection in Scapanes but not Rhynchophorus also increased in a plot of palms adjacent to the release zone. The rice inoculum could be recovered and the fungus reisolated up to 84 days after release, but infection of Scapanes continued to occur after all trace of the inoculum had disappeared.     

Population status,habitat dependence,and reproductive ecology of Bahama Orioles: a critically endangered synanthropic species

ABSTRACT Recent elevation of critically endangered Bahama Orioles (Icterus northropi) to species status prompted us to evaluate their population status, habitat use, and breeding ecology. From surveys, we estimated that at least 141 to 254 individuals remain globally, with 90 to 162, 24 to 44, and 27 to 48 individuals remaining on North Andros Island, Mangrove Cay, and South Andros Island, The Bahamas, respectively. Orioles were observed nesting exclusively in anthropogenic habitat (residential and agricultural land), but home ranges also included nearby pine forest and coppice (dry broadleaf forest). Most nests (40 of 46, or 87%) were in nonnative coconut palm (Cocos nucifera), with native Sabal palmetto and Thrinax morrisii, and an introduced Brassaia actinophylla also used. Trees selected by orioles for nesting were significantly taller, less likely to have shrubs underneath, further from cover, and had more palm trees nearby than randomly selected palm trees. Three of eight nests with known contents were parasitized by Shiny Cowbirds (Molothrus bonariensis). Lethal yellowing disease recently devastated coconut palms and reduced the number of orioles on North Andros, but palms on Mangrove Cay and South Andros remain healthy. The juxtaposition of anthropogenic habitat to suitable native habitats may be more important than any single factor for Bahama Orioles, especially for breeding adults and fledged young. Conservation of coppice habitat, at high risk for agricultural and residential development, is crucial for survival of this critically endangered synanthropic species.     

Population structure and its implications for conservation of the great silver beetle Hydrophilus piceus in Britain

1. The great silver water beetle Hydrophilus piceus is one of the largest aquatic insects in Europe. In Britain it is rare and endangered, and confined to a small number of low-lying marshes. Very little is known about the beetle populations in any of these areas, or the connectivity between them.
2. To investigate the population structure of H. piceus in Britain, four polymorphic microsatellite loci were identified and characterized. The genome of this beetle seems to have few microsatellites but contains a high proportion of a larger repeated sequence.
3. All six of the main British populations (Somerset, Lewes, Pevensey, Romney, North Kent and Norfolk) showed substantial genetic diversity at the microsatellite loci. However, estimates of effective population size at one site (Pevensey) were remarkably low, at <10 adults for the period 2004–05.
4. Most of the genetic diversity was partitioned within rather than among the populations, although there was, nevertheless, significant genetic sub-structuring. Almost all population pairwise F _st estimates were significantly different from zero, and there was a clear isolation-by-distance effect. Assignment tests and cluster analyses demonstrated interpopulation relationships largely consistent with their geographical separations.
5. Hydrophilus disperses by flight, and records from moth traps indicated that there was no month in which the beetles never flew, but that flight activity was highest in the spring.
6. The genetic data highlight the need to maintain or regenerate habitat connectivity within flying distance for H. piceus , and to sustain large areas of suitable breeding marshes.     

Biology and Structure of Phytomonas staheli sp. n., a Trypanosomatid Located in Sieve Tubes of Coconut and Oil Palms

SYNOPSIS. Phytomonas staheli sp. n. is described from the oil palm ( Elaeis guineensis ) and the coconut palm ( Cocos nucifera ) of Surinam, South America. The phytomonad is the probable cause of "Hartrot" in the coconut palm and "Marchitez sopresiva" in oil palms. Parasites are confined to the sieve tubes in palms. Some success was obtained at cultivation of the organism from Elaeis.