Susceptibility of Aethina tumida (Coleoptera: Nitidulidae) Larvae and Pupae to Entomopathogenic Nematodes

In this study, we evaluated the potential use of entomopathogenic nematodes as a control for the beetle Aethina tumida Murray (Coleoptera: Nitidulidae). In particular, we conducted 1) four screening bioassays to determine nematode (seven species, 10 total strains tested) and application level effects on A. tumida larvae and pupae, 2) a generational persistence bioassay to determine whether single inoculations with nematodes would control multiple generations of A. tumida larvae in treated soil, and 3) a field bioassay to determine whether the nematodes would remain efficacious in the field. In the screening bioassays, nematode efficacy varied significantly by tested nematode and the infective juvenile (IJ) level at which they were applied. Although nematode virulence was moderate in screening bioassays 1-3 (0 - 68% A. tumida mortality), A. tumida mortality approached higher levels in screening bioassay 4 (nearly 100% after 39 d) that suggest suitable applicability of some of the test nematodes as field controls for A. tumida. In the generational persistence bioassay, Steinernema Hobrave Cabanillas, Poinar & Raulston 7-12 strain and Heterorhabditis indica Poinar, Karunaka & David provided adequate A. tumida control for 19 wk after a single soil inoculation (76-94% mortality in A. tumida pupae). In the field bioassay, the same two nematode species also showed high virulence toward pupating A. tumida (88-100%) mortality. Our data suggest that nematode use may be an integral component of an integrated pest management scheme aimed at reducing A. tumida populations in bee colonies to tolerable levels.

Resistance against strongylid nematodes in two high prevalence Equine Recurrent Airway Obstruction families has a genetic basis

A recent study showed increased resistance against strongylid nematodes in offspring of a stallion affected by recurrent airway obstruction (RAG) compared with unrelated pasture mates. Resistance against strongylid nematodes was associated with RAG affection. Hypothesis: Resistance against strongylid nematodes has a genetic basis. The genetic variants influencing strongylid resistance also influence RAG susceptibility. Faecal samples from the half-sibling offspring of two RAG-affected Warmblood stallions 98 offspring from the first family (family 1) and 79 from the second family (family 2) were analysed using a combined sedimentation-flotation method. The phenotype was defined as a binary trait - either positive or negative for egg shedding. The influence of non-genetic factors on egg shedding was analysed using SAS, the mode of inheritance was investigated using PAP and iBay, and the association between shedding of strongyle eggs and RAG was estimated by odds ratios. Previously established genotypes for 315 microsatellite markers were used for QTL analyses using GRID QTL. The inheritance of "strongylid egg shedding" is influenced by major genes on ECA15 and ECA20. Shedding of strongylid eggs is associated with RAG in family 1 but not in family 2. Conclusions: The status of "shedding of strongyle eggs" has a genetic background. The results were inconclusive as to whether "egg shedding" and RAG share common genetic components. Our results suggest that it may be possible to select for resistance against strongylid nematodes.

Complex geomorphologic assemblage of terrains in association with the banded terrain in Hellas basin, Mars

Hellas basin acts as a major sink for the southern highlands of Mars and is likely to have recorded several episodes of sedimentation and erosion. The north-western part of the basin displays a potentially unique Amazonian landscape domain in the deepest part of Hellas, called “banded terrain”, which is a deposit characterized by an alternation of narrow band shapes and inter-bands displaying a sinuous and relatively smooth surface texture suggesting a viscous flow origin. Here we use high-resolution (HiRISE and CTX) images to assess the geomorphological interaction of the banded terrain with the surrounding geomorphologic domains in the NW interior of Hellas to gain a better understanding of the geological evolution of the region as a whole. Our analysis reveals that the banded terrain is associated with six geomorphologic domains: a central plateau named Alpheus Colles, plain deposits (P1 and P2), reticulate (RT1 and RT2) and honeycomb terrains. Based on the analysis of the geomorphology of these domains and their cross-cutting relationships, we show that no widespread deposition post-dates the formation of the banded terrain, which implies that this domain is the youngest and latest deposit of the interior of Hellas. Therefore, the level of geologic activity in the NW Hellas during the Amazonian appears to have been relatively low and restricted to modification of the landscape through mechanical weathering, aeolian and periglacial processes. Thermophysical data and cross-cutting relationships support hypotheses of modification of the honeycomb terrain via vertical rise of diapirs such as ice diapirism, and the formation of the plain deposits through deposition and remobilization of an ice-rich mantle deposit. Finally, the observed gradual transition between honeycomb and banded terrain suggests that the banded terrain may have covered a larger area of the NW interior of Hellas in the past than previously thought. This has implications on the understanding of the evolution of the deepest part of Hellas.