Plasticity of mycangia in Xylosandrus ambrosia beetles

Insects that depend on microbial mutualists evolved a variety of organs to transport the microsymbionts while dispersing. The ontogeny and variability of such organs is rarely studied, and the microsymbiont*s effects on the animal tissue development remain unknown in most cases. Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae or Platypodinae) and their mutualistic fungi are an ideal system to study the animalfungus interactions. While the interspecific diversity of their fungus transport organ一 mycangia—is well-known, their developmental plasticity has been poorly described. To determine the ontogeny of the mycangium and the influence of the symbiotic fungus on the tissue development, we dissected by hand or scanned with micro-CT the mycangia in various developmental stages in five Xylosandrus ambrosia beetle species that possess a large, mesonotal mycangium: Xylosandrus amputatus. Xylosandrus compactus, Xylosandrus crassiusculus, Xylosandrus discolor, and Xylosandrus germanus. We processed 181 beetle samples from the United States and China. All five species displayed three stages of the mycangium development:(1) young teneral adults had an empty, deflated and cryptic mycangium without fungal mass;(2) in fully mature adults during dispersal, the promesonotal membrane was inflated, and most individuals developed a mycangium mostly filled with the symbiont, though size and symmetry varied;and (3) after successful establishment of their new galleries, most females discharged the bulk of the fun gal inoculum and deflated the mycangium. Experimental aposymbiotic individuals demonstrated that the pronotal membrane invaginated independently of the presence of the fungus, but the fungus was required for inflation. Mycangia are more dynamic than previously thought, and their morphological changes correspond to the phases of the symbiosis. Importantly, studies of the fungal symbionts or plant pathogen transmission in ambrosia beetles need to consider which developmental stage to sample. We provide illustrations of the different stages, including microphotography of dissections and micro-CT scans.     

Comparative susceptibility and immune responses of Asian and European honey bees to the American foulbrood pathogen,Paenibacillus larvae

American foulbrood (AFB) disease is caused by Paenibacillus larvae. Currently, this pathogen is widespread in the European honey bee— Apis mellifera. However, little is known about infectivity and pathogenicity of P. lan'ae in the Asiatic cavity-nesting honey bees, Apis cerana. Moreover, comparative knowledge of P. larvae infectivity and pathogenicity between both honey bee species is scarce. In this study, we examined susceptibility, larval mortality, survival rate and expression of genes encoding antimicrobial peptides (AMPs) including defensin, apidaecin, abaecin, and hymenoptaecin in A. mellifera and A. cerana when infected with P. larvae. Our results showed similar effects of P. larvae on the survival rate and patterns of AMP gene expression in both honey bee species when bee larvae are infected with spores at the median lethal concentration (LC5 0 ) for A. mellifera. All AMPs of infected bee larvae showed significant upregulation compared with noninfected bee larvae in both honey bee species. However, larvae of A. cerana were more susceptible than A. mellifera when the same larval ages and spore concentration of P. larvae were used. It also appears that A. cerana showed higher levels of AMP expression than A. mellifera. This research provides the first evidence of survival rate, LC50 and immune response profiles of Asian honey bees, A. cerana, when infected by P. larvae in comparison with the European honey bee, A. mellifera.     

Genes important for survival or reproduction in Varroa destructor identified by RNAi

The Varroa mite,(Varroa destructor),is the worst threat to honey bee health worldwide.To explore the possibility of using RNA interference to control this pest, we determined the effects of knocking down various genes on Varroa mite survival and reproduction.Double-stranded RNA (dsRNA)of six candidate genes (Da,Pros26S,RpL8, RpL11,RpPO and RpS13)were synthesized and each injected into Varroa mites,then mite survival and reproduction were assessed.Injection of dsRNA for Da (Daughterless)and Pros26S (Gene for proteasome 26S subunit adenosine triphosphatase)caused a significant reduction in mite survival,with 3.57%±1.94% and 30.03%±11.43% mites surviving at 72 h post-inj ection (hpi),respectively.Control mites injected with green fluorescent protein (GFP)-dsRNA showed survival rates of 81.95%±5.03% and 82.36 ±2.81%,respectively. Injections of dsRNA for four other genes (RpL8,RpL11,RpPO and RpS13)did not affect survival significantly,enabling us to assess their effect on Varroa mite reproduction.The number of female offspring per mite was significantly reduced for mites injected with dsRNA of each of these four genes compared to their GFP-dsRNA controls.Knockdown of the target genes was verified by real-time polymerase chain reaction for two genes important for reproduction (RpL8,RpL11)and one gene important for survival (Pros26S). In conclusion,through RNA interference,we have discovered two genes important for mite survival and four genes important for mite reproduction.These genes could be explored as possible targets for the control of Varroa destructor in the future.     

Field efficacy of insect pathogen,botanical, and jasmonic acid for the management of wheat midge Sitodiplosis mosellana and the impact on adult parasitoid Macroglenes penetrans populations in spring wheat

The wheat midge, Sitodiplosis mosellana, is a serious pest of wheat worldwide. In North America, management of S. mosellana in spring wheat relies on the timely application of pesticides, based on midge adults levels caught in pheromone traps or seen via field scouting during wheat heading. In this context, biopesticides can be an effective alternative to pesticides for controlling S. mosellana within an Integrated Pest Management program. A field study using insect pathogenic fungus Beauveria bassiana GHA, nematode Steinernema Jeltiae with Barricade polymer gel 1%, pyrethrin, combined formulations of B. bassiana GHA and pyrethrin, Jasmonic acid (JA) and chlorpyrifos (chemical check) was performed to determine to which extent they affect midge larval populations, kernel damage levels, grain yield, and quality, and the impacts on adult parasitoid Macroglenes penetrans populations. The results indicated that biopesticides JA and S. Jeltiae were the most effective in reducing larval populations and kernel damage levels, and produced a higher spring wheat yield when compared to the water control at both study locations (East Valier and North Valier, Montana, USA). Increased test weight in wheat had been recorded with two previous biopesticides at East Valier but not for North Valier, when compared over water control. These results were comparable in efficacy to the chlorpyrifos. This study also suggested that B. bassiana and pyrethrin may work synergistically, as exemplified by lower total larval populations and kernel damage levels when applied together. This study did not demonstrate the effect of any treatments on M. penetrans populations.     

Vitamin D enzymes (CYP27A1, CYP27B1, and CYP24A1) and receptor expression in non-melanoma skin cancer

The relationship between vitamin D metabolic enzymes (CYP27A1, CYP27B1, and CYP24A1) and vitamin D receptor (VDR) in nonmelanoma skin cancer (NMSC) development and progression is not entirely clear. However, several clinical studies and in vitro reports indicate a connection between vitamin D metabolic key players and NMSCs by demonstrating inhibitory effects on tumor cells and positive effects in skin cancer prevention of higher circulatory 25-hydroxyvitamin D [1]. Vitamin D synthesis is mediated via mitochondrial cytochrome P450 family hydroxylase enzymatic reactions: anabolic and catabolic hydroxylases (CYP27A1, CYP27B1, and CYP24A1).     

Tameness does not correlate with the learning of an appetitive association in a wild canid

Individual differe nces in cog nition have been shown to be common in some animal taxa, and recent evidenee suggests that an individual's personality can be associated with an individuads cognitive strategy. We tested whether wild bat-eared foxes Otocyon megalotis differ in a risktaking behavior (tameness) and whether this trait correlated with appetitive association learning performanee. While our result shows that individuals differed in their tameness, we found no associati on between this personality trait and learning the appetitive association. This result does not support the framework that differe nces in cog nition are associated with differe nces in personality;however, our small sample size does not allow us to assert that pers on ality can not be associated with cog nition in this system. This study highlights that measuri ng cog nition and pers on ality in wild systems presents added difficulty and that correlations found in captive animals may not be evident in their wild counterparts.     

Mate assessment behavior is correlated to learning ability in female threespine sticklebacks

In many species, males signal quality with elaborate traits, but females often show inter-individual variation in pref ere nee for these traits. Choosi ng a mate requires multiple cog nitive steps;therefore, cog nitive style (how an in dividual processes information) likely in fluences the perception of sexual signals and ability to choose a high-quality mate. An important component of cognitive style is flexibility;cognitively flexible individuals are more perceptive to shifts in cues. We hypothesized that cognitively flexible individuals would acquire more information about potential mates, better discern between two quality-signaling traits, and thus be more discriminatory. Here, we show that mate assessment is correlated to other cognitive traits. Although we did not detect an effect of cogn itive style on mate pref ere nee or discriminatio n, we found that female threespi ne sticklebacks Gasterosteus aculeatus that spent more time assessing potential mates (more responsive) in a dichotomous mate choice task reached both the initial and reversal learning criterion in a spatial learning task with fewer errors. However, these highly responsive females made more consecutive mistakes immediately at the beginning of the reversal phase, suggest!ng that they did not quickly adapt to the en vironmental cha nge but in stead rapidly formed strict routi nes duri ng the learning task that were eventually reversible after repeated errors. Furthermore, we found evidenee for condition-dependent mate pref ere nee, with larger females preferring the high-quality male. These are among the first results that illustrate how cog nitive traits might in flue nee mate choice, which has implicati ons for the st re ngth and di recti on of sexual selection.     

Perceptual lateralization of vocal stimuli in goats

Functional asymmetries, for example, the preferential involvement of 1 brain hemisphere to process stimuli, may increase brain efficiency and the capacity to carry out tasks simultaneously. We investigated which hemisphere was primarily invoIved in processing acoustic stimuli in goats using a headorienting paradigm. Three playbacks using goat vocalizations recorded in different contexts: food anticipation (positive), isolation (negative), food frustration (negative), as well as 1 playback involving dog barks (negative) were presented on the left and right sides of the test subjects simultaneously. The head-orienting response (left or right) and latency to resume feeding were recorded. The direction of the head-orienting response did not differ between the various playbacks. However, when the head-orienting response was tested against chanee level, goats showed a right bias regardless of the stimuli presented. Goats responded more to dog barks than to food frustration calls, whereas responses to food anticipation and isolation calls were intermediate. In addition, the latency to resume feeding, an indicator of fear reaction, was not affected by the kind of vocalization presented. These results provide evidence for asymmetries in goat vocal perceptio n of emotional-li nked con specific and heterospecific calls. They also suggest involvement of the left brain hemisphere for processing acoustic stimuli, which might have been perceived as familiar and non -threate ning.     

Seeing red: color vision in the largemouth bass

How animals visually perceive the environment is key to understanding important ecological behaviors, such as predation, foraging, and mating. This study focuses on the visual system properties and visual perception of color in the largemouth bass Micropterus salmoides. This study (1) documents the number and spectral sensitivity of photoreceptors,(2) uses these parameters to model visual perception, and (3) tests the model of color perception using a behavioral assay. Bass possess single cone cells maximally sensitive at 535 nm, twin cone cells maximally sensitive at 614 nm, and rod cells maximally sensitive at 528 nm. A simple model of visual perception predicted that bass should not be able to discern between chartreuse yellow and white nor between green and blue. In contrast, bass should be able to discern red from all achromatic (i.e., gray scale) stimuli. These predictions were partially upheld in behavioral trials. In behavioral trials, bass were first trained to recognize a target color to receive a food reward, and then tested on their ability to differentiate between their target color and a color similar in brightness. Bass trained to red and green could easily discern their training color from all other colors for target colors that were similar in brightness (white and black, respectively). This study shows that bass possess dichromatic vision and do use chromatic (i.e., color) cues in making visual-based decisions.