It is broadly known that the conservation of biological diversity in agricultural ecosystems contributes to pest control. This process was studied in a prickly pear plantation (Opuntia megacanthaandOpuntia ficus-indica) located in central Mexico. No insecticides have been used on this plantation since 2000, and local farmers believe that the presence of different species of insects limits the growth of the wild cochineal (Dactylopius opuntiaeCockerell), which is one of the main pests in this crop. From August 2012 to November 2013, we estimated the number of cochineal per stem in the plantation and determined its spatial distribution pattern. In order to identify signs of population regulation, we obtained histograms of the frequency distribution of the size of the clusters and determined if distribution is adjusted to a power function (power law). We identified the cochineal predators and determined the correlation in their abundances. The greater abundance of cochineal occurred between summer and autumn while the minimum value was recorded in spring. The frequency distribution of the cochineal clusters had a high level of adjustment to a power function, suggesting the presence of population regulation processes. Six species that prey on cochineal were identified.Laetilia coccidivoraandHyperaspis trifurcatawere the most active and their abundance was significantly correlated with the abundance of cochineal. We found that the probability of extinction of these insects in a cladode increases with its density, since the density and predator activity also increased. It is likely that, under these conditions, the cochineal have established an autonomous control.
Scions collected from diseased trees and from those without symptoms of beech bark disease (BBD) were cleft-grafted in 2003 and 2004 onto rootstock of unknown resistance to BBD. Grafting success varied among genotypes and year (30% in 2003 and 12% in 2004), and improved with increasing rootstock diameter. Successful grafts were used to test resistance to the beech scale insect, Cryptococcus fagisuga (the initiating agent of BBD) by introducing eggs onto the bark of scions and allowing time for the emergence of all developmental stages of the insects. Significantly fewer insects colonized scions collected from putatively resistant trees than those collected from diseased trees. In some cases, where egg placement overlapped a portion of the rootstock, insect colonies developed on the rootstock but not on the scion collected from resistant trees. Occasionally, scions from putatively resistant trees were colonized, whereas some of those from diseased trees were not. When scions from putatively resistant trees were heavily colonized, only adult insects were present and no eggs or other life stages of the insect were found. The findings indicate that the extent of resistance to the scale insect (hence to BBD) ranges from partial to total resistance.
El pilomatrixoma es una tumuracion benigna poco frecuente piloso, es mas frecuente durante la infancia. La forma multiple de pilomatrixoma es rara y mas persinas con VIH, su presencia se asocia a sindromes sistemcios, entre los cuales destaca la distrodia miotonica. El diagnóstico definitivo de pilomatrixoma es histopatológico, aunque los estudios complementarios como la ecografía son útiles para confirmar el mismo. El tratamiento curativo es la resección quirúrgica de la lesión, con baja tasa de recurrencia. Se presenta el caso clínico de un paciente de sexo masculino con VIH, de 50 años de edad, con diagnóstico de pilomatrixoma de características clínicas inusuales: forma múltiple y crecimiento rápido.
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