International audienceA major issue of potato cultivation in temperate zones is the potato cyst nematode Globodera rostochiensis. Population density of G. rostochiensis is high in Mexican potato fields. Control currently consists of the inefficient application of high doses of chemical nematicides. We evaluated the population density of G. rostochiensis in potato production plots in central Veracruz, Mexico. Plots were treated with the biocontrol agent Paecilomyces sp. and rotation with two different leguminous crop plants, Pisum sativum and Vicia faba. A random block experimental design was used with four different treatments over two crop cycles: (1) biological control with crop rotation, (2) crop rotation only, (3) biological control applied to soil left in fallow, and (4) soil left in fallow only. We measured the number and content of cysts, and the number of J2 juveniles of G. rostochiensis in the soil. We then estimated the infestation level in soil and the multiplication rate (Pf/Pi). The number of free-living nematodes was also quantified. Results show that the highest mitigation of G. rostochiensis was observed for the biological control rotation, with 89.2 % reduction, and for the biological control fallow treatments with 84.4 % reduction. In rotation plots, infestation level decreased by 30.7 %. In the biological control rotation and biological control fallow treatments, the Pf/Pi was 0.1 and 0.15, respectively. The highest Pf/Pi of 0.93 was found in the fallow plots. The biological control agent did not significantly affect the free-living nematode populations. In this study, the nematophagous fungus Paecilomyces sp. was used for the first time to efficiently reduce the population of G. rostochiensis in two crop cycles
Thirteen helminth species were recorded during a helminthological examination of 754 Girardinichthys multiradiatus (Meek) (Pisces: Goodeidae) collected from 20 localities in the upper Lerma River sub-basin on the highland plateau of Mexico. The study constitutes a complete and extensive inventory of the helminth parasites of this freshwater fish species across its entire current geographic distribution. The collected species included one adult trematode, three metacercariae, one monogenean, one adult cestode, three metacestodes, three nematode larvae and one cystacanth. The records of the metacercariae of Tylodelphys sp. and Ochetosoma brevicaecum, the larvae of the nematodes Contracaecum sp. and Falcaustra sp. and the cystacanth of Polymorphus brevis are all new records for G. multiradiatus. The metacercariae of Tylodelphys sp. were the most widespread and prevalent species in the sample, being collected from 15 of the 20 sampling localities, with a prevalence of 3.2-72.2%. The data indicate the helminth parasite community of G. multiradiatus to be relatively poor when compared with the helminth communities of freshwater fish from other parts of Mexico. This community is subject to colonization by generalist helminth species, mostly transported by birds. A further component of this community consists of helminth species that have been introduced anthropogenically.
Resumen. Se realizó un inventario y se calcularon los parámetros de infección de los helmintos gastrointestinales de 36 ejemplares de aves acuáticas pertenecientes a las familias Anatidae, Rallidae y Threskiornithidae, procedentes de la subcuenca alta del río Lerma, Estado de México, identificándose 20 especies: 9 tremátodos, 8 céstodos, 2 nemátodos y 1 acantocéfalo. De las 8 especies de céstodos, 6 son registros nuevos para el país y Pseudocorynosoma constrictum se registra por primera vez en Anas crecca, Anas discors, Oxyura jamaicensis y Fulica americana. Los helmintos que presentaron las prevalencias más altas fueron los céstodos Hymenolepis megalops y Sobolevicanthus krabbeella en Anas acuta, Anas clypeata, Anas cyanoptera y Anas crecca.
During the period from January to December (2007), 1,095 freshwater molluscs of four species were captured (Lymnaea stagnalis, Stagnicola elodes, Physella cubensis and Physa acuta) in Lake Chicnahuapan, State of Mexico, Mexico. Two hundred seventy-two (24.84% prevalence) of these molluscs were parasitised by 11 trematode species (from which two were not identified at the species level) having six cercariae species and five metacercariae species represented in five families. The cercariae Telorchis corti (Plagiorchiidae) and the metacercariae Cotylurus cornutus (Strigeidae) were the species with the highest prevalence among the examined snails. The highest percentage of infection was observed in L. stagnalis (27.45% of prevalence, n = 572) and P. cubensis (23.96%, n = 455). Twenty-one of the examined snails had multiple infections with up to three trematode species.
Ciliates are a morphologically diverse group of protists inhabiting aquatic and terrestrial ecosystems. We studied the taxonomy and ecology of free-living ciliates from a freshwater marsh in Central Mexico during the period from 2012 to 2013 during both dry and rainy seasons. We found 30 ciliate species recorded for the first time from Atarasquillo marsh in Mexico, most of which are common species in freshwater ecosystems. The species richness was higher during the dry season than rainy season. Five trophic groups were observed: bacterivorous, bacteria-algae-heterotrophic flagellate consumers (BAF-consumers), omnivorous, predators, and mixotrophic species. The trophic group composition changed according to the season and the environmental conditions, e.g. vegetation and water level. Generally bacterivorous ciliates were more frequent during the rainy season, meanwhile the omnivorous during the dry season; thus, the feeding strategies in ciliates were different between both seasons. Due to the fact that Atarasquillo marsh is in a deterioration process, ciliate records could be used to assess water quality.
Se determinaron y clasifi caron en grupos trófi cos las especies de nematodos asociados a la rizosfera de Solanum tuberosum en suelos altamente infectados por el nematodo dorado de la papa (Globodera rostochiensis) en un ciclo de cultivo, en la zona productora del Cofre de Perote, Veracruz, México. Se identifi caron 7 géneros (Aphelenchoides, Aphelenchus, Crassolabium, Mesodorylaimus, Plectus y Steinernema) y 8 especies (Aporcelaimellus obtusicaudatus, Ecumenicus monohystera, Acrobeles mariannae, Acrobeles singulus, Acrobeloides nanus, Cruznema tripartitum, Eucephalobus oxyuroides, y Globodera rostochiensis) en asociación con la rizosfera de papas cultivadas. Crassolabium sp. y E. monohystera se registran por primera vez para México. Palabras clave: nematodos, cultivo de papa, grupos trófi cos.
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