Tag: agriculture

Scientists forecast where is the highly invasive fall armyworm to strike next

*The fall armyworm is the larvae of the fall armyworm moth species Spodoptera frugiperda. Photo by Centre for Agriculture and Bioscience International (CABI).*

Staple and economically important crops throughout the world could be at serious risk if efficient measures are not taken soon

Known to be feeding on many economically important crops cultured across the world, including maize, rice, sugarcane, sorghum, beet, tomato, potato, cotton and pasture grasses, the larvae of the native to the Americas fall armyworm moth seem to have already found a successful survival strategy in a diverse and changing world.

Furthermore, having taken no longer than 2 years to invade and spread throughout most of sub-Saharan Africa, the pest has already demonstrated its huge potential in severely affecting livelihoods around the globe.

A recent study in the open-access journal NeoBiota, conducted by Dr Regan Early of Exeter University, United Kingdom and her colleagues at the Centre for Agriculture and Bioscience International: Dr Pablo González-Moreno, Sean T. Murphy and Roger Day, looks into the factors and likelihood for the fall armyworm (Spodoptera frugiperda) to spread to other regions and continents.

Invasion progress

The alarming reports started in January 2016 when major outbreaks of fall armyworms were registered in Nigeria and Ghana, preceding signals from Benin, Sao Tomé and Togo shortly after. By September 2017, the pest had already been confirmed in 28 sub-Saharan African countries, with nine states expected to follow suit.

While unaided dispersal of the species in Africa is considered unlikely, it is speculated that the pest had arrived on a passenger flight from America. To back this theory, the researchers point out that the first countries to house the invader are also the major air transportation hubs in Africa and have warm, moist climate similar to those in the pest’s natural habitat.

In the aftermath, recent estimates point to up to 50% maize yield loss in Africa attributed to the fall armyworm. However, scientists believe that the species is far from finished spreading and is highly likely to invade new continents.

Who’s next?

To find what makes a region an inviting new habitat for the fall armyworm, hence which countries face the highest threat of future invasions, the researchers looked into both the native and African distributions of the species, and the effects different temperatures and precipitation levels have on it.

Having concluded that the lowest temperatures and the maximum amount of rain play the main role in determining whether the fall armyworm is to establish in a certain region, the scientists concluded that South and Southeast Asia, as well as Australia face the most serious risk, since their climate is very similar to the one preferred by the pest.

However, the authors of the study remind that this forecast shall in no way be taken with a sigh of relief by countries with milder climatic conditions. While the moth needs particular temperature and precipitation amplitudes at its year-round habitat, it could easily travel back and forth up to several hundred kilometres during its seasonal migrations. Therefore, if the fall armyworm establishes in North Africa, it could migrate to Europe during the warmer months, just like it has already been observed to travel from its year-round localities in Argentina, Texas and Florida all the way to Canada’s Québec and Ontario in the north.

The increasing transportation and international trade are also likely to facilitate the further spread of the fall armyworm outside Africa. The scientists conclude that, given the current travel air routes, it is Australia, China, India, Indonesia, Malaysia, Philippines and Thailand which are at high risk of becoming the pest’s new habitat.

*The map illustrates the likelihood of the establishment of the fall armyworm if introduced at different parts of the world. Image by Regan Early.*

What’s next?

Having concluded that there is a considerable potential for near global invasion and seasonal migration of fall armyworm, the scientists call for vigilance from farmers and programme managers alike. They remind that early detection of small larvae is crucial, since it is only at this stage that chemical insecticides would work effectively.

“As fall armyworm has huge potential to affect staple and economic crops globally, we urgently need information on the pest’s potential distribution and environmental limitations,” comment the researchers.

“Management decisions would be improved by further research on fall armyworm’s seasonal migration and population dynamics and the environmental dependency of interactions with other species.”

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Original source:

Early R, González-Moreno P, Murphy ST, Day R (2018) Forecasting the global extent of invasion of the cereal pest Spodoptera frugiperda, the fall armyworm. NeoBiota 40: 25-50. https://doi.org/10.3897/neobiota.40.28165

A preprint of the study was published earlier on bioRxiv.

New fungus found to cause cankers and declines in pistachio trees in Sicily, Italy

Starting in the spring of 2010, farmers from Sicily – the major pistachio production area of Italy – have been reporting a previously unknown disease on the trees. Characterised by cankers and declines, it sometimes leads to the collapse of the entire plant.

When the research team led by Salvatore Vitale, Centro di Ricerca Difesa e Certificazione, Italy, studied plants from a total of 15 pistachio orchards in Catania, Agrigento and Caltanissetta provinces, they identified cankers associated with vascular necrosis and tree decline on twigs, branches and stems, alongside abundant gummosis. There were also localised, sunken lesions with several central cracks. These lesions would deepen into the woody tissue, where discolouration and necrotic tissue were also present.

Additionally, the scientists conducted a series of pathogenicity tests on 5-year-old potted pistachio plants (Pistacia vera), which successfully reproduced the field observations. As a result, a previously unknown pathogenic fungus, which colonises the woody plant tissue, has been isolated.

*Timelapse of the symptoms reproduced in a potted plant.*

The aetiology of the disease and the description of the new species, named Liberomyces pistaciae, are published in the open access journal MycoKeys. Despite cankers and subsequent decline of pistachio trees having been observed in Sicily for several years, the paper is the first work to successfully determine the causal agent.

“On the basis of the high disease incidence and the frequency of this species observed in several orchards in the last years, we believe that L. pistaciae represents amenace to pistachio production in Sicily,” say the researchers.

*Symptoms caused by the newly described pathogenic fungus observed in the field.*

Out of the 15 surveyed orchards, the scientists detected the presence of the fungus in ten of them. Most of the observations occurred in the winter period and during late spring, but the authors found the pathogen in asymptomatic trees as well, which suggests that the fungus has a dormant growth phase.

When already symptomatic, the plants begin to exudate gum. Often, the bark on their trunks and/or branches would scale, appearing as if cracking and peeling. The initial pale circular areas present in the bark turn dark and sunken with time. Later, the infected patches were seen to expand in all directions, yet faster along the main axis of the stems, branches and twigs. When the scientists examined beneath the bark, they saw discoloured and necrotic tissues. Once the trunk of the tree is encircled by a canker, they report, the whole plant collapses.

Other symptoms include canopy decline as well as wilting and dying inflorescences and shoots growing from infected branches or twigs.

The newly described fungus is characterised with slowly growing colonies. With time, they turn from white to pale to dark brown with a whitish slightly lobed margin.

The researchers warn that essential hazard for the further spread and promotion of the infection is the use and distribution of infected propagation material taken from nurseries and mechanical injuries or pruning wounds.

Further research and studies are currently in progress aiming to extend the survey to other areas in order to eventually formulate effective disease management strategies.

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Original source:

Vitale S, Aiello D, Guarnaccia V, Luongo L, Galli M, Crous PW, Polizzi G, Belisario A, Voglmayr H (2018) Liberomyces pistaciae sp. nov., the causal agent of pistachio cankers and decline in Italy. MycoKeys 40: 29-51. https://doi.org/10.3897/mycokeys.40.28636

When lemons give you life: Herpetofauna adaptation to citrus orchards in Belize

Natural habitat areas exhibit similar abundances and diversity of herpetofauna as citrus orchards and reclaimed orchard forests in Stann Creek, Belize, reports a comparative study by researchers Russell Gray and Dr. Colin Strine of Suranaree University of Technology (SUT), Thailand.

The scientists utilized several drift-fence arrays equipped with double-funnel traps to monitor and compare reptile and amphibian communities in a lowland broadleaf forest, a lime orchard and a reclaimed citrus orchard at the Toucan Ridge Ecology and Education Society (TREES) field station. Their study was recently published in the open-access journal ZooKeys.

Often referred to as Central America’s “hidden gem” for its abundance of undisturbed rainforests and natural beauty, Belize has a long-standing record for vigorously protecting and maintaining their forested areas. However, just as in any other developing country, its primary sector is expanding with agricultural land clearings becoming more frequent with newly established properties.

Approximately midway through the study (June – September 2016), the site was hit by Hurricane Earl, a Category 1 hurricane. The hurricane-force winds altered the canopy cover significantly over the forested study sites, due to felled trees and broken branches.

Surprisingly enough, the herpetofauna remained relatively unchanged in the aftermath of Earl. The phenomenon revealed that not only were herpetofaunal communities lacking sensitivity to anthropogenic changes in the area, but also to extreme weather events, even though these had affected most of the standing vegetation.

Some notable observations occurred within three days of Hurricane Earl, according to Russell Gray:

“One of the trapping system was catching arboreal [tree climbing] snake species, like the cat-eyed snake and blunt-headed tree snake. This wasn’t only interesting because arboreal snakes were caught in terrestrial traps, but rather because they were never caught in our traps during the study up to this point.”

“Even more interesting is that they were caught exclusively in the manicured orchard area, which makes me wonder if they somehow predicted falling trees and fled to the only habitat without them. Some animals appear to forecast weather events due to sudden or drastic changes in environmental conditions. I wonder if this is a similar case.”

Amongst other notable scientific discoveries reported during the project were two new accounts of the Petén Centipede Snake (Tantilla hendersoni), one of which was the first documented male of the species. This secretive snake had only been documented once prior to the study and is the only endemic snake species to Belize.

Further noteworthy instances were two range extensions for relatively data deficient species – one for the Doflein’s Salamander (Bolitoglossa dofleini) and another for the Ringneck Coffee Snake (Ninia diademata).

Besides providing important data on herpetofauna assemblages in various disturbed and undisturbed habitats in Belize, the research identifies future conservation methods to be considered.

The study serves as new evidence that as long as agricultural areas remain surrounded with natural habitat buffers, they have little effect on herpetofaunal communities.

Replicates of this study are encouraged by the authors and can be utilized as a feasible and efficient way to monitor reptiles and amphibians in Belize.

Although Belize still preserves a considerable amount of intact forest cover, there are several on-going conservation concerns. Besides agricultural land clearings, there are constant struggles with xate poachers, or “Xateros”, on the Guatemalan border, as well as illegal logging activities and illegal off-season hunting.

Unfortunately, reptiles and amphibians have been understudied in comparison to other vertebrates and government action is rarely enforced on their conservation throughout the Neotropics.

A striking example of this relates to the only critically endangered reptile in Belize – the Hickatee turtle (Dermatemys mawii). Although the species is likely to become extinct, it is still traditionally collected for its culinary value, while its hunting is banned only in May.

In conclusion, the authors note that it is crucial to pay close attention to anthropogenic activity and the potential repercussions it may have on native species. With extensive and active efforts to study Mesoamerican herpetofauna, proper conservation efforts can be implemented and focused.

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Original Source:

Gray R, Strine CT (2017) Herpetofaunal assemblages of a lowland broadleaf forest, an overgrown orchard forest and a lime orchard in Stann Creek, Belize. ZooKeys 707: 131-165. https://doi.org/10.3897/zookeys.707.14029

Survival of soil organisms is a wake-up call for biosecurity

Tiny creatures in soil that attack plants have shown the ability to survive for at least three years stored in dry conditions in a recent AgResearch study, giving new insights into the biosecurity threats posed by passenger travel and trade between countries. The research article is published in the open access journal Neobiota.

The findings of the study also add to the discussions about how best to detect these creatures, called nematodes, before they cross borders and potentially reduce yields of important crops and pasture.

Nematodes are very small worm-like organisms. They can be extremely hardy and can have both beneficial and detrimental impacts. The harmful ones, the plant parasitic nematodes (PPN) include species that attack plants reducing their growth and survival.

In the study, funded by AgResearch via the Better Border Biosecurity collaboration, soil collected from a native forest and an organic orchard was stored separately in cupboards at room temperature for a period of 36 months.

Samples were then taken at regular intervals to see if any nematodes could be recovered from the soil and, if they could, whether they were able to infect plant hosts.

“In the study we used different methods to detect nematodes — including a water misting technique to draw them out of the soil, and a baiting method — where we grew white clover and ryegrass plants in pots containing a soil sample,” explain the authors.

“One of the PPN we looked at was the root lesion nematode. What we found was that lesion nematodes were able to successfully invade the roots of ryegrass even after 36 months,” says AgResearch nematologist Lee Aalders.

“They were also able to produce offspring at 13 months. Interestingly, no PPN were recovered from soil stored beyond the 13th month using the three-day misting technique.”

This means that given the right conditions, PPN in soil, which is carried on sea freight, footwear or used machinery, and protected from sun or extreme heat, will survive if they end up near a suitable host plant. This is a result that may not be detected using an extraction test like misting.

For quarantine officials around the world, this result is an important find, as it reinforces the risk associated with soil that, even though it may look sterile, unwanted nematodes may be present and undetected until paired with a suitable host plant.

“In the context of biosecurity, we think that the development of a generic test for plant parasitic nematodes – based around a molecular based bioassay — would enhance the probability of detection of PPNs and, therefore, prevent unwanted incursions beyond the border.”

Earlier this year, another AgResearch study into the survival rates of various transported soil organisms and published in Neobiota concluded that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes.

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Original source:

Aalders LT, McNeill MR, Bell NL, Cameron C (2017) Plant parasitic nematode survival and detection to inform biosecurity risk assessment. NeoBiota 36: 1-16. https://doi.org/10.3897/neobiota.36.11418

Robust rattan palm assessed as Endangered, new Species Conservation Profile shows

An African rattan palm species has recently been assessed as Endangered, according to the IUCN Red List criteria. Although looking pretty robust at height of up to 40 m, the palm is restricted to scattered patches of land across an area of 40 km². It grows in reserves and conservation areas in Ghana and a single forest patch in Côte d’Ivoire. Its Species Conservation Profile is published in the open access Biodiversity Data Journal by an international research team, led by Thomas Couvreur, Institut de Recherche pour le Développement (IRD), France, in collaboration with the University of Yaoundé, Cameroon, Royal Botanic Gardens, Kew, UK, and the Conservatoire et jardin botaniques, Geneva, Switzerland.

The rattan palm is confined to moist evergreen forests with high rainfall, located at 100 to 200 meters above sea level. The species is poorly known, yet it is likely very rare judging from the limited amount of forest habitat remaining across its range. Furthermore, the known populations are isolated from each other by large distances, which makes them particularly vulnerable.

Even though there are gaps of knowledge concerning the rattan palm species, the research team conclude that it is most likely currently declining, due to habitat loss, fragmentation and over-harvesting. Often mistaken for a sister species, commonly used in trade, the stems of the endangered species are largely used in furniture production. When longitudinally split into ribbons, the canes are also used as ropes for thatching, for making baskets and sieves, and to make traps.

“As with most African rattan species, there is inadequate information on the international trade, but it is likely to be negligible,” explain the scientists.

“Conservation measures are urgently needed to protect the habitat of this species and to control the unsustainable harvest of the stems. A promising solution might be sustainable cultivation of rattans to avoid the exploitation of wild populations,” suggests Ariane Cosiaux (IRD), the lead author of the study currently based in Cameroon.

With their present paper, the authors make use of a specialised novel publication type feature, called Species Conservation Profile, created by Biodiversity Data Journal, to provide scholarly credit and citation for the IUCN Red List species page, as well as pinpoint the population trends and the reasons behind them.

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Original source:

Cosiaux A, Gardiner L, Ouattara D, Stauffer F, Sonké B, Couvreur T (2017) An endangered West African rattan palm: Eremospatha dransfieldii. Biodiversity Data Journal 5: e11176. https://doi.org/10.3897/BDJ.5.e11176

Cage the fly: Walk-in field cages to assess mating compatibility in pest fruit flies

Fruit flies mating compatibility studies have been examined by an international team of researchers to assess the usefulness of walk-in field cages in studying the sexual behavior within fruit fly species complexes and recognition of taxonomically misplaced flies. In addition, they have also evaluated the relevant chemical signals during pheromone emission for species discrimination. The experimental part was conducted with the support of Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture in Seibersdorf, Austria. Their findings are published in the open-access journal ZooKeys.

Evolution has led to divergence in some groups, which sometimes results in new, yet very similar species. Hence, they might successfully confuse taxonomists, making them coin terms like ‘cryptic’ species, or in other words, distinct species misplaced under the same name.

However, these species are kept isolated from each other via reproductive barriers. Preventing interbreeding and hybridization, they can be ecological and mechanical, but also behavioral (i.e. sexual). The latter are behaviors or signals that affect recognition within a species, as well as attractiveness and mate choice. They affect their evolution and therefore, are key elements in species differentiation.

The authors of the present paper have found that the walk-in field cages methodology provides an appropriate ground to study these issues. By applying it, researchers around the world are able to detect pest species among others when occurring in the same populations.

Apart from taxonomic value, the scientists also point out the significance of these findings to pest management. As the studied pest fruit fly species are agricultural pests of major economic importance, assessing their mating behaviour, including the pheromones the males emit when attracting partners, can be utilised in the development of highly specific control methods. For instance, there is the sterile insect technique that involves releasing males reproductively sterilised via ionizing radiation into a wild population, where they inseminate the pest females with sterile sperm so that they end up with unviable offspring.

The main advantage of using walk-in field cages, rather than small laboratory-based ones, is that they provide semi-natural conditions under which they are “reliable and powerful tools to measure the level of mating compatibility among different species and populations of a putative single species.”

However, the present paper highlights that such an approach is only to be applied as a part of integrative taxonomic analyses, together with molecular, physiological and morphological approaches when assessing to which species a particular pest population belongs.

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Original source:

Juarez ML, Devescovi F, Brizova R, Bachmann G, Segura DF, Kalinova B, Fernandez P, Ruiz MJ, Yang J, Teal PEA, Caceres C,, Vreysen MJB, Hendrichs J, Vera MT (2015) Evaluating mating compatibility within fruit fly cryptic species complexes and the potential role of sex pheromones in pre-mating isolation. In: De Meyer M, Clarke AR, Vera MT, Hendrichs J (Eds) Resolution of Cryptic Species Complexes of Tephritid Pests to Enhance SIT Application and Facilitate International Trade. ZooKeys 540: 125-155. doi: 10.3897/zookeys.540.6133

Parasite vs. Invader: New endoparasitoid wasp can save the Dominican Republic economy

While biocontrol agents come in different shapes, often taking a lot of time for scientists to research, test and produce, natural ones always seem to be the better option. Now that Drs. Taveras and Hansson have discovered a new parasitoid wasp species in the Dominican Republic, they might have not only met the worst natural enemy for a widely spread invasive pest corrupting a large part of the essential pigeon pea crops. They are likely to have found a whole new field for investigation into the potential weapons against the eradicator of up to 76% of the essential crop. Their study is available in the open access Journal of Hymenoptera Research.

The find of this new gregarious endoparasitoid wasp, called Pediobius cajanus, is also the first time representative of this genus has been retrieved from the Asian fly. This invasive pest is estimated to destroy a huge part of the pigeon pea crops, a culture which is an essential food source for tropical America, a large part of the export and even has medicinal value. Therefore, the new species is very important not only in terms of the exploration of the biodiversity in Latin America, but also in economical sense.

Even when treated regularly with insecticides, the Asian fly manages to corrupt as much as 27% of the Dominican pigeon pea crops, a previous study shows. Although a precise figure of the damage cannot be provided due to large variations between localities and the impossibility of tracking the whole span of the pea cultivation areas, there is the case of the town of Rancho Los Vargas, Puerto Plata, where in 2012 the loss of the culture reached 76%.

On the other hand, the new wasp species was found to kill an average of 25% of the Asian fly larvae in the researched areas. In comparison, the previously known enemies of the pest are accountable for only 2%. This is why the scientists are now proposing the new species as a biocontrol agent.

In conclusion, the authors suggest that the parasitoid wasp is likely distributed across a much larger area. They believe that the new species could also be found over the entire island of Hispaniola, on neighbouring islands in the Caribbean and even in the tropical parts of the mainland in the Americas. Its record and distribution both call for a further investigation into the potential implementation of the wasp in controlling the Asian fly.

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Original source:

Taveras R, Hansson C (2015) Pediobius cajanus sp. n. (Hymenoptera, Eulophidae), an important natural enemy of the Asian fly (Melanagromyza obtusa (Malloch)) (Diptera, Agromyzidae) in the Dominican Republic. Journal of Hymenoptera Research 45: 41-54. doi: 10.3897/JHR.45.4964