The role of citizen science in addressing grand challenges in food and agriculture research.

The power of citizen science to contribute to both science and society is gaining increased recognition, particularly in physics and biology. Although there is a long history of public engagement in agriculture and food science, the term 'citizen science' has rarely been applied to these efforts. Similarly, in the emerging field of citizen science, most new citizen science projects do not focus on food or agriculture. Here, we convened thought leaders from a broad range of fields related to citizen science, agriculture, and food science to highlight key opportunities for bridging these overlapping yet disconnected communities/fields and identify ways to leverage their respective strengths. Specifically, we show that (i) citizen science projects are addressing many grand challenges facing our food systems, as outlined by the United States National Institute of Food and Agriculture, as well as broader Sustainable Development Goals set by the United Nations Development Programme, (ii) there exist emerging opportunities and unique challenges for citizen science in agriculture/food research, and (iii) the greatest opportunities for the development of citizen science projects in agriculture and food science will be gained by using the existing infrastructure and tools of Extension programmes and through the engagement of urban communities. Further, we argue there is no better time to foster greater collaboration between these fields given the trend of shrinking Extension programmes, the increasing need to apply innovative solutions to address rising demands on agricultural systems, and the exponential growth of the field of citizen science.

Non-homologous DNA increases gene disruption efficiency by altering DNA repair outcomes.

The Cas9 endonuclease can be targeted to genomic sequences by programming the sequence of an associated single guide RNA (sgRNA). For unknown reasons, the activity of these Cas9-sgRNA combinations varies widely at different genomic loci and in different cell types. Thus, disrupting genes in polyploid cell lines or when using poorly performing sgRNAs can require extensive downstream screening to identify homozygous clones. Here we find that non-homologous single-stranded DNA greatly stimulates Cas9-mediated gene disruption in the absence of homology-directed repair. This stimulation increases the frequency of clones with homozygous gene disruptions and rescues otherwise ineffective sgRNAs. The molecular outcome of enhanced gene disruption depends upon cellular context, stimulating deletion of genomic sequence or insertion of non-homologous DNA at the edited locus in a cell line specific manner. Non-homologous DNA appears to divert cells towards error-prone instead of error-free repair pathways, dramatically increasing the frequency of gene disruption.

Psychometric characteristics of the minimum data set II: validity.

OBJECTIVE: To determine the validity of the Minimum Data Set (MDS). DESIGN: MDS domain scores were correlated with a variety of independently obtained measures of basic behavioral and mental health functions of 513 nursing home residents. SETTING: All participants were residents of the Philadelphia Geriatric Center. PARTICIPANTS: One group of residents (n = 260) represented consecutive admissions who were able to respond to formal testing. The other group of residents (n = 253) represented presumably cognitively impaired residents whose data did not depend on self-report. MEASUREMENTS: MDS item-composite scores based on a confirmatory factor analysis were derived for the domains of cognition, activities of daily living (ADL), time use, depression, and problem behaviors. Hypotheses stating how these MDS domains should be related to standard measures of cognitive function, ADL, depression, agitation, social behavior, and irritability were tested. CONCLUSIONS: The majority of the hypotheses were upheld, thus suggesting that the MDS is usable as a source of research data. The sizes of the validity coefficients were modest, however. Depression and problem behavior were less well affirmed than cognition, ADL, and Time Use. There is a clear need for improvement in training and probably in the form of MDS measurement in some areas.

Potential impact of wildlife on the tropical bont tick eradication program in the Caribbean.

Wildlife are hosts for A. variegatum throughout its range in Africa, and have been demonstrated to serve as hosts for larvae and nymphs on several islands in the Caribbean. Studies conducted in the Caribbean have indicated that most larvae and nymphs and all adults of the tick feed on livestock; therefore, eradication can be approached through the treatment of livestock. However, since small numbers of animals such as the mongoose are infested with larvae and nymphs, these animals may represent a short-term alternative host system. Such infestations potentially could result in a presence of small numbers of ticks for up to 46 months after the onset of a treatment program and could serve as a source to reinfest livestock during the eradication process. Wildlife surveys have been conducted in St. Croix, Puerto Rico, Guadeloupe, and Antigua; but the host status of species present on other islands such as the white-tailed deer on St. Kitts has not been evaluated. As part of the eradication program, the species of wildlife present on each island and the association of these species with infested pastures should be determined. Surveys of wildlife can be used during the eradication to determine if wildlife are serving as an alternative host system. Cattle egrets may serve to disseminate the tick among islands in the region, and to areas outside the region. Cattle egrets have been shown to serve as hosts for the tick, and to move throughout the eastern Caribbean and to North America. The potential for interisland dissemination of ticks by cattle egrets, as well as by other means, substantiates the need for a region-wide eradication program.

Vesicular stomatitis virus, New Jersey serotype: replication in and transmission by Lutzomyia shannoni (Diptera: Psychodidae).

Laboratory-reared female sand flies (Lutzomyia shannoni) were experimentally infected, orally and by intrathoracic inoculation, with the New Jersey serotype of vesicular stomatitis (VSNJ) virus. Virus replication occurred in the insects following infection by both routes. Virus titers greater than 10(4) plaque forming units of VSNJ virus were present in heads of orally infected sand flies 12 days after virus ingestion, confirming that a persistent disseminated infection had occurred. Both orally and parenterally infected Lu. shannoni transmitted VSNJ virus by bite to susceptible rodents and by transovarial transmission to a small percentage of their F1 progeny. The significance of these findings in the epizootiology of VSNJ virus on Ossabaw Island, Georgia, an enzootic focus of this virus, is discussed.

Isolation of vesicular stomatitis virus New Jersey serotype from phlebotomine sand flies in Georgia.

Vesicular stomatitis virus New Jersey serotype (VSNJ virus) was isolated from 6 of 610 pools of phlebotomine sand flies (Lutzomyia shannoni) collected on Ossabaw Island, GA. All isolates were from non-blooded females. Infected sand flies were collected at 6 sites at 5 separate times from 3 June through 25 July 1988. Thirty-five pools of Culicoides ssp. and 48 pools of mosquitoes obtained in conjunction with the infected sand flies also were evaluated for VSNJ virus; all were negative. Concomitant serologic monitoring of sentinel swine indicated that VSNJ virus transmission began in late April and continued through the completion of this study in August. The incidence of seroconversion among the sentinel wild swine was 50%. Domestic sentinel swine did not seroconvert at 2 sentinel sites, 1 of 2 seroconverted at 1 site, and 2 of 2 seroconverted at the fourth site. Vesicular lesions were seen on 10 sentinel wild swine during the summer. Vesicular stomatitis virus (NJ) was isolated from 4 of these swine and was diagnosed in 1 additional swine by direct complement-fixation assay. The time period within which VSNJ virus was isolated from sand flies preceded detection of vesicular lesions but corresponded with the period of seroconversion in sentinel swine. Site specific data indicated that VSNJ virus activity was widespread within the study area.

Funnel trap for the capture of phlebotomine sand flies (Diptera: Psychodidae) from tree holes.

A funnel trap that fitted over holes leading into hollow trees was used to capture adult phlebotomine sand flies, Lutzomyia shannoni Dyar, on Ossabaw Island, Chatham County, Ga. These insects rested in hollow trees during the day and were collected by funnel traps as they egressed from the tree holes at night. The trap is lightweight, durable, inexpensive, waterproof, and selective. Using this trap, greater than 100 healthy L. shannoni ++were captured per night by a single investigator during July and August 1988 when adult flies were abundant on the island.

Effect of acaricide treatment of cattle on Amblyomma variegatum (Acari: Ixodidae) infestation of mongooses (Carnivora: Viverridae: Herpestes auropunctatus) in Guadeloupe, French West Indies.

The effect of acaricide treatment of cattle on the infestation of the small Indian mongoose (Herpestes auropunctatus Hodgson) by Amblyomma variegatum (F.) was determined during a field evaluation of selected acaricides in Guadeloupe, French West Indies. From April 1990 to April 1991, cattle at one site were treated every 14 d with pour-on formulations of deltamethrin, flumethrin, or permethrin; and cattle at a second site were treated as per a local standard treatment using a spray formulation of coumaphos every 30 d. The protocol was then reversed, and from April to July 1991 cattle at the original standard treatment site were treated using the pour-on treatment. Mongooses were examined for ticks during February-March and July 1990 and 1991. The mean prevalence of infestation of mongooses by A. variegatum larvae was reduced from 41 to 27% during the February-March to July periods at the pour-on treatment sites but increased from 29 to 43% during the same periods at the standard treatment sites. The mean relative density of infestation by larvae decreased from 2.15 to 0.65 at the pour-on treatment sites and increased from 0.7 to 1.95 at the standard treatment sites during the same periods. Data on nymphal infestations were inconclusive, and mongooses were not infested by adult ticks. The infestation of mongooses by A. variegatum may be of importance as a short-term alternative host system for immature stages of this tick during an eradication program.

Population dynamics of Lutzomyia shannoni (Diptera: Psychodidae) in relation to the epizootiology of vesicular stomatitis virus on Ossabaw Island, Georgia.

Population dynamics of Lutzomyia shannoni Dyar were studied on Ossabaw Island, GA, to define further the role of this species in the epizootiology of the New Jersey serotype of vesicular stomatitis (VSNJ) virus. Bimonthly collections of sand flies egressing from hollow trees from April to November 1991 indicated that there were three generations of sand flies. Data from light trap collections from 1986 through 1989 indicated that similar seasonal cycles occurred during previous years. At this site, we hypothesize that L. shannoni undergoes facultative diapause. Two isolates of VSNJ virus were obtained from female sand flies collected in May and June of 1991. We believe that the virus overwinters in immature L. shannoni and that transovarially infected sand flies emerging each spring initiate a summer amplification cycle in swine on Ossabaw Island.

Wildlife as hosts for ticks (Acari) in Antigua, West Indies.

A survey was conducted to determine the status of wild mammals and birds as hosts for Amblyomma variegatum (F.) and other tick species in Antigua. Surveys of wild mammals and birds were conducted periodically from September 1988 through May 1991. Wild mammals surveyed included the small Indian mongoose (Herpestes auropunctatus Hodgson), Norway rat (Rattus norvegicus Berkenhout), and house mouse (Mus musculus L.), but only mongooses were surveyed intensively. Larvae and nymphs of A. variegatum, larvae of Boophilus microplus (Canestrini), and larvae of Ornithodoros puertoricensis (Fox) were recovered. The mean prevalences of infestation of mongooses by A. variegatum larvae and nymphs were 4.7 and 1.3%, respectively; maximums were 16.1 and 5.0%, respectively. The mean prevalence of infestation of mongooses by B. microplus was 3.2%. O. puertoricensis is reported from Antigua for the first time. The mean prevalence of infestation of mongooses by O. puertoricensis larvae was 41.2%, but seasonal prevalences ranged from 27.8 to 55.0%. Of 610 birds representing 16 species, three Carib grackles (Quiscalus lugubris Swainson) were each infested with one larva of A. variegatum.

Titers of vesicular stomatitis virus, New Jersey serotype, in naturally infected male and female Lutzomyia shannoni (Diptera: Psychodidae) in Georgia.

Seven isolates of the New Jersey serotype of vesicular stomatitis (VSNJ) virus were obtained from pooled specimens of phlebotomine sand flies, Lutzomyia shannoni Dyar, collected on Ossabaw Island, Chatham County, Ga., in 1989 and 1990. Three isolates, including two from males, were obtained from light-trapped sand flies in 1989. Four isolates were obtained from pools of sand flies collected from hollow trees in 1990. Three of the latter pools contained from 4.0 to 4.7 log10 of plaque-forming units of virus per ml, suggesting that the positive flies in these pools had supported VSNJ virus replication. One of these high-titered isolates was obtained from a pool of male sand flies. These data provide further support for the hypotheses that L. shannoni is a biological vector of VSNJ virus at this enzootic focus and that transovarial transmission of the virus occurs in nature.

Potential role of cattle egrets, Bubulcus ibis (Ciconiformes: Ardeidae), in the dissemination of Amblyomma variegatum (Acari: Ixodidae) in the eastern Caribbean.

The potential role of cattle egrets, Bubulcus ibis (L.), in the dissemination of Amblyomma variegatum (F.) in the eastern Caribbean was evaluated. The status of cattle egrets as hosts for A. variegatum in Antigua was determined during seven survey periods between September 1988 and May 1991. The mean prevalences of infestation by larvae and nymphs were 2.3 and 0.5%, respectively. The mean intensity and relative density of infestation by larvae were 8.8 (SD = 9.80) and 0.2 (SD = 0.28), respectively. Cattle egrets examined in Guadeloupe during February-March 1991 were not infested but 5.9% were infested by larvae during June-July 1991. Interisland movement of cattle egrets was evaluated relative to emigration of birds captured and marked in Antigua and Guadeloupe. During this aspect of the study, 1,129 cattle egrets were captured, marked, and released. Of 195 sighting reports received, 56 were determined to be independent sightings. Emigration of cattle egrets included movement of birds marked in Antigua or Guadeloupe to 14 Caribbean islands and the Florida Keys. Interisland movement occurred in each of the discrete observation periods during the 3-yr study period. The rate of emigration per period ranged from 1.2 to 12.9%. That cattle egrets served as hosts for immature A. variegatum in the eastern Caribbean and moved between islands in the region demonstrates that these birds could serve as disseminators of the tick. Estimates of the numbers of infested cattle egrets emigrating from Antigua and Guadeloupe ranged from 0 to 0.24% of the current populations.

Effect of forest type on the distribution of Lutzomyia shannoni (Diptera: Psychodidae) and vesicular stomatitis virus on Ossabaw Island, Georgia.

We studied the effects of three forest types on multiple factors that are believed to influence the transmission of the New Jersey serotype of vesicular stomatitis (VSNJ) virus on Ossabaw Island, GA. These factors included availability of tree hole diurnal resting habitat for the presumed sand fly vector, Lutzomyia shannoni Dyar; relative abundance of L. shannoni; prevalence of VSNJ virus infection in sand flies; and prevalence of VSNJ virus antibodies in wild swine. Tree hole availability, sand fly abundance, and antibody prevalence in swine were significantly greater in maritime live oak forest than in other forest types. A single isolate of VSNJ virus was obtained from sand flies collected in maritime live oak forest. These data indicate that the relative abundance of adult L. shannoni is influenced significantly by the availability of tree holes and that VSNJ virus infection in wild swine is linked to forest type and is greatest in areas capable of supporting abundant populations of L. shannoni.

Epidemiological study of Campylobacter spp. in broilers: source, time of colonization, and prevalence.

From October 1993 to August 1994, broiler chickens in four grow-out houses, two previously used (houses 1 and 2) and two newly constructed (houses 3 and 4), were used in a study to determine the source, time of infection, and prevalence of Campylobacter spp. Cecal droppings and cecal samples were obtained from the broilers. Samples were also obtained from water, feed, litter, soil, fans, and workers' boots. Samples were obtained from domestic animals and wildlife species (rectal swabs), including insects, on or near the premises. Broilers in houses 2, 3, and 4 became infected in the second or third week and were fully colonized by day 42. Campylobacter appeared in house 1 during week 2 in a low percentage of the birds, disappearing by the fourth week. Isolates were also recovered from domestic pigs and water on this farm. In house 3, the organism was isolated from workers' boots and a wild bird prior to isolation from the broilers. Following isolation from cecal droppings, the organism was isolated from water, feed, litter, feathers, flies, cattle, feces, and wild animals. In house 2, Campylobacter was isolated from cattle feces and wild birds prior to week 5, when the broilers first became infected, and thereafter from water, feed, insect, and wildlife, and cecal droppings. It was subsequently isolated from workers' boots, cattle feces, feathers, insects, and other wildlife. All ceca taken from 20 birds each from houses 2 and 3 were positive at time of slaughter (day 49). All ceca from house 1 were negative. No ceca were collected from birds originating in house 4. No specific source could be identified from the samples obtained, although apparently the organism permeates the environment and several potential sources are discussed in this paper.

Mycoplasma gallisepticum in house finches (Carpodacus mexicanus) and other wild birds associated with poultry production facilities.

Since 1994, an epidemic of conjunctivitis caused by Mycoplasma gallisepticum (MG) has spread throughout the eastern population of house finches (Carpodacus mexicanus). The adaptation of MG to a free-flying avian species presents potential problems for the control of mycoplasmosis in commercial poultry. To evaluate risks associated with this emerging problem, a field survey was conducted to assess prevalence of MG infection in house finches and other passerine birds associated with poultry farms. Between November 1997 and March 1999, 1058 birds were captured by mist net or trap at 17 farms and at 10 feeder stations in northeast Georgia. Birds were bled and screened by serum plate agglutination (SPA) for antibodies to MG. Birds with negative or weak positive SPA results were released at capture sites, and those with strong positive SPA reactions were kept for further evaluation. Necropsies were performed on selected house finches and individuals of 11 other passerine species, and samples were collected for MG testing by culture, polymerase chain reaction (PCR), hemagglutination inhibition, and histopathology. Testing revealed 19.1% of 671 birds caught at farms and 11.6% of 387 birds caught at feeder sites were SPA positive for MG. Three house finches captured on farms were positive for MG by culture and PCR, whereas three from feeder sites were positive only by PCR. No MG isolates were made from tufted titmice (Baeolophus bicolor), but 40% were positive by PCR. Individuals from 10 additional species were SPA positive only. Results suggest that MG persists at low levels in house finches in northeast Georgia and that tufted titmice may be nonclinical carriers of MG or a related mycoplasma. Positive SPA reactions in other species may be caused by nonspecific reactions or contact exposure. Current biosecurity recommendations should be sufficient to minimize risks of transmission between wild and domestic birds.

Pasteurella multocida in wild mammals and birds in California: prevalence and virulence for turkeys.

Samples collected from the oropharynx of wild mammals and birds trapped on 36 turkey farms in California were evaluated for the presence of Pasteurella multocida. A total of 966 animals were collected from 18 premises that had experienced an outbreak of fowl cholera within the past 2-8 months; samples were collected from 16 of these 18 premises within 2-8 weeks of outbreak notification and while the infected flock was still present. A total of 939 animals were trapped from an additional 18 premises that had not reported any outbreaks of fowl cholera within at least 4 months, if ever. Forty-eight isolates of P. multocida, of a variety of somatic serotypes, were recovered from 6 species of mammals and 3 species of birds. On only 2 of 7 premises was the somatic serotype of the isolates obtained from wildlife the same as the isolate obtained from tissues of turkeys that had died of fowl cholera on the same premises. Tests for virulence to turkeys were conducted with 31 of the isolates. Seventeen of these isolates caused mortality in turkeys. Wide ranges in mortality rates and median times to death were observed.

Disinfection and wildlife.

Capture, handling or transport of wildlife for purposes such as research, disease monitoring, wildlife damage control, relocation, and collection of zoological specimens can create risks of disease spread. Cleaning and disinfection procedures for equipment used in these activities must be routine and designed to eliminate the spread of pathogens to either animals or humans. General methods and materials for cleaning and disinfection apply to wildlife studies. Concepts involved in preparing a protocol specific to a wildlife investigation are discussed. The control of the spread of livestock and poultry pathogens via free-ranging mammals and birds prior to disinfection of contaminated premises is approached through an accurate assessment of the problem and, where necessary, the selection of appropriate wildlife control measures. The authors discuss the development of a problem assessment, and review potential methods for use in the control of wildlife. For an accurate problem assessment, information is needed on the presence of wild mammals and birds at the site, exposure of wild mammals and birds to the pathogen, and the potential for further transmission. When wildlife control is deemed necessary, techniques may be selected to disperse or exclude animals from premises or to depopulate the site. Dispersal or exclusion from premises is appropriate when movement of animals within or away from the contaminated premises would not result in further transmission of the pathogen. Depopulation is necessary when the continued presence or dispersal of wild mammals or birds would potentially result in further spread of the disease.

Lutzomyia shannoni (Diptera: Psychodidae): a biological vector of the New Jersey serotype of vesicular stomatitis virus on Ossabaw Island, Georgia.

The New Jersey serotype of vesicular stomatitis virus (VSNJ) is enzootic on Ossabaw Island, Georgia. Lutzomyia shannoni is the only phlebotomine sand fly present on the island and there is strong evidence that it is a vector of the virus at this site. This overview summarizes the studies that have been done on the island, reviews the evidence which confirms that L. shannoni is a biological vector of VSNJ, and discusses remaining unknown aspects of the epizootiology of VSNJ.

Toxicological investigation of liquid petroleum gas explosion: human model for propane/ethyl mercaptan exposures.

Four individuals died as the result of a propane explosion. As with many propane explosions, the question was raised as to the adequacy of the product's odorization after the autopsy studies had been conducted. In most cases, this question leads to litigation. Ethyl mercaptan is a widely used odorant for propane and was used in this instance. Three of the four victims had blood available at autopsy for study. Quantitative analyses of the victims' blood, obtained during autopsy, were performed using gas chromatography/mass spectrometry, without subjecting the samples to hydrolysis. These analyses determined the relative amounts of propane and ethyl mercaptan in the blood to be 90, 63, and 175 mL/m3 headspace, and 0.36, 0.34, and 0.77 microgram/L blood, respectively. Since mercaptans have been reported in human blood as products of metabolism, modeling studies were conducted to establish the validity of the autopsy data and to develop an autopsy toxicology protocol for investigating explosion deaths. When subjects were not exposed to an atmosphere containing ethyl mercaptan, dimethylsulfide was the only mercaptan detectable in their blood without severe hydrolysis prior to analysis. Metabolic ethyl mercaptan is sufficiently bound to be undetectable by the methods used without hydrolysis. Human subjects were exposed to a flammable mixture of air and propane odorized with ethyl mercaptan. The analyses of the blood from these subjects produced results which were comparable with those for the explosion victims, establishing that the question of odorant adequacy can be addressed at the autopsy of propane explosion victims. It is extremely important that the pathologist and toxicologist investigating gas explosion deaths recognize the valuable evidence existing in the victim's blood.

Health protocol for translocation of free-ranging elk.

When considering an elk (Cervus elaphus) restoration program, wildlife managers must evaluate the positive and negative elements of translocation. We prepared this protocol to give an overview of health considerations associated with translocation of elk, with an emphasis on movement of free-ranging elk from western North America to the southeastern USA. We evaluated infectious agents and ectoparasites reported in elk from two perspectives. First, we made a qualitative estimate of the ability of the agent to be introduced and to become established. This was done using a selected set of epidemiologic factors. Second, if there was a good possibility that the organism could become established in the release area, the potential pathological consequences for elk and other wildlife, domestic animals, and humans were assessed via examination of the literature and consultation with other animal health specialists. The results of these evaluations were used to classify infectious agents and ectoparasites as low risk (n = 174), unknown risk (n = 10), and high risk (n = 9). We classified Anaplasma marginale, Anaplasma ovis, Mycobacterium paratuberculosis, Pasteurella multocida serotype 3, Elaphostrongylus cervi, Dicrocoelium dendriticum, Fascioloides magna, Echinococcus granulosus, Dermacentor albipictus, and Otobius megnini as unknown risks. High risk infectious agents and ectoparasites were the agent of chronic wasting disease, Brucella abortus, Mycobacterium bovis, Dermacentor andersoni, Ixodes pacificus, and Psoroptes sp. Parelaphostrongylus tennis, Elaeophora schneideri, and a Babesia sp. are parasites endemic in the southeastern USA that may present a "reverse risk" and adversely affect elk if released in some parts of the region. We developed a five-component protocol to reduce the risk of introduction of high risk infectious agents and ectoparasites that included: (1) evaluation of the health status of source populations, (2) quarantines, (3) physical examination and diagnostic testing, (4) restrictions on translocation of animals from certain geographic areas or populations, and (5) prophylactic treatment.