Tag: agriculture

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