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.     

Oryctes rhinoceros populations and behavior influenced by a baculovirus

Oryctes rhinoceros adults stopped feeding and flew less frequently, and the males mated less often after they became infected with the baculovirus of Oryctes. Monitoring the larval and adult population in Western Samoa over several years gave evidence that the incidence of the virus is dependent on the density of the O. rhinoceros population. Male beetles were more frequently infected than female bettles. Adding more virus-infected beetles to the O. rhinoceros populations of Nukunonu Atoll, where the virus had become established 5 years earlier, reduced the population significantly. The data indicated that the reduction was caused mainly by a decrease in the number of eggs deposited.     

Natural history of a bighorn sheep pneumonia epizootic: Source of infection,course of disease,and pathogen clearance

A respiratory disease epizootic at the National Bison Range (NBR) in Montana in 2016–2017 caused an 85% decline in the bighorn sheep population, documented by observations of its unmarked but individually identifiable members, the subjects of an ongoing long‐term study. The index case was likely one of a small group of young bighorn sheep on a short‐term exploratory foray in early summer of 2016. Disease subsequently spread through the population, with peak mortality in September and October and continuing signs of respiratory disease and sporadic mortality of all age classes through early July 2017. Body condition scores and clinical signs suggested that the disease affected ewe groups before rams, although by the end of the epizootic, ram mortality (90% of 71) exceeded ewe mortality (79% of 84). Microbiological sampling 10 years to 3 months prior to the epizootic had documented no evidence of infection or exposure to Mycoplasma ovipneumoniae at NBR, but during the epizootic, a single genetic strain of M. ovipneumoniae was detected in affected animals. Retrospective screening of domestic sheep flocks near the NBR identified the same genetic strain in one flock, presumptively the source of the epizootic infection. Evidence of fatal lamb pneumonia was observed during the first two lambing seasons following the epizootic but was absent during the third season following the death of the last identified M. ovipneumoniae carrier ewe. Monitoring of life‐history traits prior to the epizootic provided no evidence that environmentally and/or demographically induced nutritional or other stress contributed to the epizootic. Furthermore, the epizootic occurred despite proactive management actions undertaken to reduce risk of disease and increase resilience in this population. This closely observed bighorn sheep epizootic uniquely illustrates the natural history of the disease including the (presumptive) source of spillover, course, severity, and eventual pathogen clearance.     

Studies on Rhabdionvirus oryctes: II. Effect on adults of Oryctes rhinoceros

Rhabdionvirus oryctes multiplies in adults of Oryctes rhinoceros. Adults and larvae of O. rhinoceros showed no significant difference in their susceptibility to the virus when it was inoculated into the hemocoel. Adults, collected from the natural population in Western Samoa, were found to be frequently infected with Rhabdionvirus. In the laboratory the infected adults had a shorter life-span and laid fewer eggs than the noninfected ones. Infected adults excreted virus material into the surrounding medium. This suggests a possible means of transmission of the virus in the field.     

The outbreak of carp disease caused by CyHV-3 as a model for new emerging viral diseases in aquaculture: a review

Aquacultured koi and common carp (Cyprinus carpio) are intensively bred for ornamental purposes and for human consumption worldwide. The carp and koi farming industries have suffered enormous economic losses over the past decade due to an epizootic disease caused by Cyprinus herpesvirus-3 (CyHV-3) also known as koi herpesvirus and carp interstitial nephritis gill necrosis virus. CyHV-3 is a large dsDNA virus, morphologically similar to herpesviruses, yet contains genetic elements similar to those of pox, irido- and herpesviruses. Considering the phylogenic distance between CyHV-3 and higher vertebrate herpesviruses, CyHV-3 represents the prototype of viruses assigned to the novel family Alloherpesviridae. Although emergence of a new virus rarely initiates a pandemic so severe that it reduces the life expectancy of a population, CyHV-3 is exceptional because of its enormous impact on the world carp population. High population density is the major contributing factor to the epizootic disease caused by CyHV-3.     

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.     

A new variant of Autographa californica nuclear polyhedrosis virus

A variant of the baculovirus, Autographa californica nuclear polyhedrosis virus, has been isolated in Idaho during an epizootic disease in a field population of A. californica. Genotypic characterization indicates that the virus is distinct from variants previously characterized. Analysis of five clones, derived by plaque purification in cell culture, indicates relative homogeneity of the original virus isolate. Further exploration of the factors involved in natural genetic variability of baculoviruses is appropriate.     

Cordyline ovens (Umu Ti) in Samoa

In ancient Samoa,Cordyline roots were prepared for use as a candy and a sweetening agent by baking in large buried stone ovens for several days. In a modern attempt to duplicate this ancient technology,Cordyline terminalis roots collected in the mountains of Upolu, Western Samoa, were baked in both a modern propane oven and in an oven orumu prepared in the traditional manner. The success of this attempt is described, together with its significance for ethnobotanical and archaeological studies in Samoa.     

Landscape-Genetic Analysis of Population Structure in the Texas Gray Fox Oral Rabies Vaccination Zone

ABSTRACT In west-central Texas, USA, abatement efforts for the gray fox (Urocyon cinereoargenteus) rabies epizootic illustrate the difficulties inherent in large-scale management of wildlife disease. The rabies epizootic has been managed through a cooperative oral rabies vaccination program (ORV) since 1996. Millions of edible baits containing a rabies vaccine have been distributed annually in a 16-km to 24-km zone around the perimeter of the epizootic, which encompasses a geographic area >4 × 10⁵ km². The ORV program successfully halted expansion of the epizootic into metropolitan areas but has not achieved the ultimate goal of eradication. Rabies activity in gray fox continues to occur periodically outside the ORV zone, preventing ORV zone contraction and dissipation of the epizootic. We employed a landscape-genetic approach to assess gray fox population structure and dispersal in the affected area, with the aim of assisting rabies management efforts. No unique genetic clusters or population boundaries were detected. Instead, foxes were weakly structured over the entire region in an isolation by distance pattern. Local subpopulations appeared to be genetically non-independent over distances >30 km, implying that long-distance movements or dispersal may have been common in the region. We concluded that gray foxes in west-central Texas have a high potential for long-distance rabies virus trafficking. Thus, a 16-km to 24-km ORV zone may be too narrow to contain the fox rabies epizootic. Continued expansion of the ORV zone, although costly, may be critical to the long-term goal of eliminating the Texas fox rabies virus variant from the United States.     

Migratory Birds Reinforce Local Circulation of Avian Influenza Viruses

Migratory and resident hosts have been hypothesized to fulfil distinct roles in infectious disease dynamics. However, the contribution of resident and migratory hosts to wildlife infectious disease epidemiology, including that of low pathogenic avian influenza virus (LPAIV) in wild birds, has largely remained unstudied. During an autumn H3 LPAIV epizootic in free-living mallards (Anas platyrhynchos) — a partially migratory species — we identified resident and migratory host populations using stable hydrogen isotope analysis of flight feathers. We investigated the role of migratory and resident hosts separately in the introduction and maintenance of H3 LPAIV during the epizootic. To test this we analysed (i) H3 virus kinship, (ii) temporal patterns in H3 virus prevalence and shedding and (iii) H3-specific antibody prevalence in relation to host migratory strategy. We demonstrate that the H3 LPAIV strain causing the epizootic most likely originated from a single introduction, followed by local clonal expansion. The H3 LPAIV strain was genetically unrelated to H3 LPAIV detected both before and after the epizootic at the study site. During the LPAIV epizootic, migratory mallards were more often infected with H3 LPAIV than residents. Low titres of H3-specific antibodies were detected in only a few residents and migrants. Our results suggest that in this LPAIV epizootic, a single H3 virus was present in resident mallards prior to arrival of migratory mallards followed by a period of virus amplification, importantly associated with the influx of migratory mallards. Thus migrants are suggested to act as local amplifiers rather than the often suggested role as vectors importing novel strains from afar. Our study exemplifies that a multifaceted interdisciplinary approach offers promising opportunities to elucidate the role of migratory and resident hosts in infectious disease dynamics in wildlife.     

Ecological description of ground beetle communities (Coleoptera, Carabidae) in northern taiga meadows of Arkhangelsk Region

Species composition and ecological structure of ground beetle population was studied in northern taiga meadows of the Arkhangelsk Region. Meadows in the northern forest zone proved to harbor 91 ground beetle species. Carabid complexes formed in the intrazonal biocenoses of the northern forest zone can be as rich as the family topical groups in the southern forest zone by the number of species and ecological diversity. Ecological properties of the fauna and ground beetle population proved similar in different parts of the forest zone. The proportion of stenobiotic meadow species proved to decrease while that of ecologically plastic ones increased from south to north. The proportion of the genus Harpalus decreased in the ground beetle population while the number of Amara species remained unaltered and their abundance increased. The changes in the species composition caused no transformation of the ecological structure of ground beetle population since they were limited to a single life form or guild.     

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.

     

Eliminating Tobacco Rattle Virus from Viruliferous Paratrichodorus allius and Establishing a New Virus-Vector Combination

A reliable method to eliminate tobacco rattle virus (TRV) from viruliferous Paratrichodorus allius populations was developed. This virus is vectored by P. allius in the Pacific Northwest and causes corky ringspot disease (CRS) of potato. The viruliferous nematodes that were reared on ''Vernema'' alfalfa or ''770'' scotch spearmint for at least 3 months did not transmit TRV to ''Samsun NN'' tobacco, a suitable indicator plant, and did not cause CRS symptoms on ''Russet Norkotah'' tubers. A new isolate of TRV was introduced into a nonviruliferous population of P. allius. First, tobacco plants were inoculated with a field population of P. allius that transmitted an isolate of TRV that caused severe symptoms on potato. The tobacco roots were then washed free from soil and dipped in 0.525% sodium hypochlorite to remove the initial nematode inoculum. After the disinfected tobacco plants recovered and began to grow, the virus-free population of P. allius was introduced around the root system to acquire the new virus isolate from tobacco roots. The newly established virus-vector combination caused CRS symptoms on ''Russet Norkotah'' that were characteristic of the more virulent virus isolate, indicating that the virus-free P. allius population had reacquired virus.     

Bovine Respiratory Syncytial Virus

A large epizootic of an acute respiratory disease of cattle occurred in Japan during the months from October 1968 to May 1969. A virus was recovered in primary cultures of calf kidney and testicle cells from nasal swabs of affected cattle. Neutralization tests revealed the virus to be closely related to the Long strain of human respiratory syncytial virus. The virus induced cytopathic changes including the formation of syncytia and acidophilic-cytoplasmic inclusions in calf kidney and testicle cell cultures. A calf inoculated with the virus by the respiratory route developed an illness resembling the natural disease. Most cattle clinically diagnosed as having the disease showed significant rises of neutralizing antibody titer for the isolated virus, whereas none or only small fractions of those animals showed serological evidence for recent infection with bovine ephemeral fever virus, infectious bovine rhinotracheitis virus, Ibaraki virus, bovine diarrhea virus, bovine adenovirus Type 7 and parainfluenza virus Type 3. Neutralization tests on paired sera revealed a wide dissemination of the isolated virus among cattle in many areas of the country during the epizootic. All these findings leave no doubt that the epizootic was caused by bovine respiratory syncytial virus. This is the first study that ever shows the presence of infection of cattle with this virus in Japan.     

Epizootiological study ofNeozygites parvispora (Zygomycota: Entomophthoraceae) in a population ofFrankliniella occidentalis (Thysanoptera: Thripidae) on pepper in sicily

This paper describes an epizootic of the entomopathogenic fungusNeozygites parvispora occurring in a population ofFrankliniella occidentalis in a pepper crop under plastic-house, in south-eastern Sicily (Italy). The progress of the epizootic in the thrips population was monitored weekly, from December 1990 to April 1991. Infections ofN. parvispora caused up to more than 60% mortality of the mobile developmental stages of the thrips, reducing consistently both the insect population density and the proportion of flowers and leaves infested by thrips. All mobile developmental stages of the thrips (adults, 1 st- and 2nd-instar larvae) were susceptible to the infections ofN. parvispora. The incidence of mycosis in each developmental stage was positively correlated with its respective proportion in the thrips population.     

Studies on Rhabdionvirus oryctes: III. Incidence in the Oryctes rhinoceros population of Western Samoa

The viral pathogen Rhabdionvirus oryctes [ROV] was found to be widespread in the population of Oryctes rhinoceros in Western Samoa. About 3% of the larvae and 35% of the adults were infected with ROV. Larval breeding sites more frequently contained ROV-infected insects if the sites were occupied by two broods instead of one and if there was a high density of breeding in the area. Females infected with ROV visited the breeding sites less frequently for egg-laying than healthy females. The male adults, as they increased in age, were found to be more frequently infected with ROV, but the young female adults were more frequently infected than very young or old females. The ROV-infections in adults apparently play a more important role in suppressing the O. rhinoceros population than those of larvae.     

Aerosol transmission of a viable virus affecting swine: Explanation of an epizootic of pseudorabies

A Gaussian diffusion model was applied to an epizootic of pseudorabies in ten swine herds located in Decatur County, Indiana, USA to test the hypothesis that the virus can be spread via aerosol. The epizootic occurred during January to March, 1988, spreading through ten farms across an area of about 150 km². The model included a receptor component that provided an estimate of viruses received by the pig within an enclosed barn. Results show that the diffusion model can explain the spread of the virus during the epizootic for all nine farms to which the virus spread.     

Review on microbial control of insect pests in forests in Japan

In Japan, two different serious defoliators were controlled by viruses:Dendrolimus spectabilis using cytoplasmic polyhedrosis virus andLymantria fumida using cytoplasmic and nuclear polyhedrosis viruses. For controllingD. spectabilis, good results were obtained when the spraying was done against old larvae of intermediate population density. AgainstL. fumida, a mixed suspension of native nuclear and cytoplasmic polyhedrosis viruses was sprayed at the early stage. The epizootic was initiated earlier than being supposed, and the population collapsed.     

Association between polymorphisms in OAS2 and CD209 genes and predisposition to chronic hepatitis C in Russian population

Chronic hepatitis C is a severe liver disease caused by positive-strand RNA virus. Previously, we reported an association between seven single nucleotide polymorphisms (SNPs) in four innate immunity genes (OAS2, OAS3, CD209, and TLR3) and human predisposition to tick-borne encephalitis, caused by a virus from the same Flaviviridae family, in a Russian population. Currently, genotype and allele frequencies for these SNPs were analyzed in 75 chronic hepatitis C patients and compared with the population control (269 Novosibirsk citizens). Data obtained suggest that the OAS2 rs1293762 and CD209 rs2287886 SNPs are associated with predisposition to chronic hepatitis C in Russian population.     

Kin selection and male androphilia in Samoan fa'afafine

The Kin Selection Hypothesis for male androphilia posits that genes for male androphilia can be maintained in the population if the fitness costs of not reproducing directly are offset by enhancing inclusive fitness. In theory, androphilic males can increase their inclusive fitness by directing altruistic behavior toward kin, which, in turn, allows kin to increase their reproductive success. Previous research conducted in Western countries has failed to find any support for this hypothesis. The current study tests this basic prediction of the Kin Selection Hypothesis for male androphilia by comparing the altruistic tendencies of androphilic and gynephilic males in the Polynesian nation of Independent Samoa. In Independent Samoa, androphilic males are known locally as fa'afafine. Altruistic tendencies were assessed using a Kin Selection Questionnaire. Comparisons of the altruistic tendencies of fa'afafine and gynephilic men revealed that these two groups did not differ in terms of their overall generosity and allocation of financial resources toward kin, nor did they differ in terms of general neediness or financial resources obtained from kin. Fa'afafine did, however, report greater avuncular tendencies than gynephilic men. Although the greater avuncular tendencies of fa'afafine support the basic prediction of the Kin Selection Hypothesis for male androphilia, further research is needed before one can conclude that these elevated tendencies represent a specially designed adaptation for promoting the fitness of kin. We discuss a number of sociocultural factors that might promote the expression of avuncular tendencies by androphilic males in Independent Samoa. Our results underscore the importance of testing functional hypotheses in evolutionarily appropriate environments.