Nematodes associated with Ips cembrae (Coleoptera: Curculionidae): comparison of generations,sexes and sampling methods

A study of nematodes associated with the large larch bark beetle Ips cembrae (Heer 1836) was carried out at three locations in the Czech Republic. The proportion of beetles infested by endoparasitic nematodes (representatives of genera Contortylenchus, Parasitylenchus, Cryptaphelenchus and Parasitorhabditis) ranged from 29.9 to 50.9%. Significant differences were determined in nematode infestation levels among locations, generations and sampling methods. No differences were found in infestation rates between males and females. The percentage of bark beetles with phoretic nematodes ranged from 18 to 42.9%. Phoretic nematodes directly found under elytra, on wings and between body segments of the bark beetles belong to the genus Micoletzkya. However, adults and juveniles of other two phoretic species Laimaphelenchus penardi and Bursaphelenchus sp. were found in the gallery frass of I. cembrae. Infestation by phoretic nematodes positively correlated with the presence of mites under elytra.     

Molecular mechanism underlying pseudopeloria in Habenaria radiata (Orchidaceae)

Habenaria radiata (Orchidaceae) has two whorls of perianth, comprising three greenish sepals, two white petals and one lip (labellum). By contrast, the pseudopeloric (with a decreased degree of zygomorphy) mutant cultivar of H. radiata , ‘Hishou’, has changes in the identities of the dorsal sepal to a petaloid organ and the two ventral sepals to lip‐like organs. Here, we isolated four DEFICIENS ‐ like and two AGL 6 ‐like genes from H. radiata , and characterized their expression. Most of these genes revealed similar expression patterns in the wild type and in the ‘Hishou’ cultivar, except Hr DEF ‐C3. The Hr DEF ‐C3 gene was expressed in petals and lip in the wild type but was ectopically expressed in sepal, petals, lip, leaf, root and bulb in ‘Hishou’. Sequence analysis of the Hr DEF ‐C3 loci revealed that the ‘Hishou’ genome harbored two types of Hr DEF ‐C3 genes: one identical to wild‐type Hr DEF ‐C3 and the other carrying a retrotransposon insertion in its promoter. Genetic linkage analysis of the progeny derived from an intraspecific cross between ‘Hishou’ and the wild type demonstrated that the mutant pseudopeloric trait was dominantly inherited and was linked to the Hr DEF ‐C3 gene carrying the retrotransposon. These results indicate that the pseudopeloric phenotype is caused by retrotransposon insertion in the Hr DEF ‐C3 promoter, resulting in the ectopic expression of Hr DEF ‐C3 . As the expression of Hr AGL 6‐C2 was limited to lateral sepals and lip, the overlapping expression of Hr DEF ‐C3 and Hr AGL 6‐C2 is likely to be responsible for the sepal to lip‐like identity in the lateral sepals of the ‘Hishou’ cultivar.     

Evolution of the Dynein Heavy Chain Family in Ciliates

Dynein heavy chains are motor proteins that comprise a large gene family found across eukaryotes. We have investigated this gene family in four ciliate species: Ichthyophthirius, Oxytricha, Paramecium, and Tetrahymena. Ciliates appear to encode more dynein heavy chain genes than most eukaryotes. Phylogenetic comparisons demonstrated that the last common ancestor of the ciliates that were examined expressed at least 14 types of dynein heavy chains with most of the expansion coming from the single‐headed inner arm dyneins. Each of the dyneins most likely performed different functions within the cell.     

Evaluating the capacity of plant DNA barcodes to discriminate species of cotton (Gossypium: Malvaceae)

Although two plastid regions have been adopted as the standard markers for plant DNA barcoding, their limited resolution has provoked the consideration of other gene regions, especially in taxonomically diverse genera. The genus Gossypium (cotton) includes eight diploid genome groups (A–G, and K) and five allotetraploid species which are difficult to discriminate morphologically. In this study, we tested the effectiveness of three widely used markers (matK, rbcL, and ITS2) in the discrimination of 20 diploid and five tetraploid species of cotton. Sequences were analysed locus‐wise and in combinations to determine the most effective strategy for species identification. Sequence recovery was high, ranging from 92% to 100% with mean pairwise interspecific distance highest for ITS2 (3.68%) and lowest for rbcL (0.43%). At a 0.5% threshold, the combination of matK+ITS2 produced the greatest number of species clusters. Based on ‘best match’ analysis, the combination of matK+ITS2 was best, while based on ‘all species barcodes’ analysis, ITS2 gave the highest percentage of correct species identifications (98.93%). The combination of sequences for all three markers produced the best resolved tree. The disparity index test based on matK+rbcL+ITS2 was significant (P < 0.05) for a higher number of species pairs than the individual gene sequences. Although all three barcodes separated the species with respect to their genome type, no single combination of barcodes could differentiate all the Gossypium species, and tetraploid species were particularly difficult.     

Population viability analysis of Walia ibex (Capra walie) at Simien Mountains National Park (SMNP), Ethiopia

Population viability analysis (PVA) has been applied to the management of many threatened populations. The objective of this study was, therefore, to estimate the PVA of Walia ibex at the Simen Mountains National Park, in the north‐central highlands of Ethiopia, with respect to population growth parameters, the probability of the population reaching a lower extinction threshold and the mean time to extinction. Direct census of the population was carried out in 2009. Secondary census data were also collected from park authorities and the literature reviews. The result revealed that the estimates of the infinitesimal mean, μ (0.04117) was greater than the infinitesimal variance, σ² (0.0219). The probability that the population reaches the extinction threshold was very low (0.15%). The mean time required for the counts to decline from the existing population size to one individual animal was 160 years. But threatened species are adversely affected by changes in landscape. These changes can be brought by short‐ and long‐term human and climate change impacts, respectively. Therefore, with the absence of environmental and demographic stochasticity and, with the application of appropriate reproductions and habitat management, the population of Walia ibex will be viable and reaches its mean time of extinctions after 160 years.     

Pyrazine emission by a tropical firefly: An example of chemical aposematism?

Although famous for photic courtship displays, fireflies (Coleoptera: Lampyridae) are also notable for emitting strong odors when molested. The identity of volatile emissions and their possible role, along with photic signals, as aposematic warnings of unpalatability have been little explored, especially in tropical species. Pursuant to the observation that the widespread Neotropical fireflies, Photuris trivittata and Bicellonycha amoena, emit pungent odors, glows, and flashes when handled, we investigated their cuticular and headspace chemistry. Gas chromatography–mass spectrometry analyses revealed that both fireflies have species‐specific cuticular hydrocarbon profiles. Photuris trivittata headspace was dominated by 2‐methoxy‐3‐(1‐methylpropyl) pyrazine (hereafter, pyrazine), on the order of 1.59 ng/individual and a suite of sesquiterpenes, while B. amoena emitted 3‐methoxy‐2‐butenoic acid methyl ester and a few ketones. This is the first report of such compounds in fireflies. We investigated the role of pyrazine in P. trivittata's interactions with potential predators: sympatric ants, toads, and bats. Solvent‐washed P. trivittata painted with pyrazine incurred lower ant predation than did their solvent‐washed counterparts. Pyrazine significantly repelled ants at baits in concentrations as low as 9.8 × 10^?4 ng/μl. The toad, Rhinella marina, readily accepted intact fireflies, pyrazine‐coated and uncoated mealworms. Both Myotis nigricans and Molossus molossus bats rejected fireflies, but accepted both pyrazine‐coated and uncoated mealworms. While pyrazine repels ants, its role as an aposematic signal warning other potential predators of firefly distastefulness requires further investigation. Our results underscore the idea that multiple enemies exert conflicting selection on firefly defenses.     

Efficient distinction of invasive aquatic plant species from non‐invasive related species using DNA barcoding

Biological invasions are regarded as threats to global biodiversity. Among invasive aliens, a number of plant species belonging to the genera Myriophyllum, Ludwigia and Cabomba, and to the Hydrocharitaceae family pose a particular ecological threat to water bodies. Therefore, one would try to prevent them from entering a country. However, many related species are commercially traded, and distinguishing invasive from non‐invasive species based on morphology alone is often difficult for plants in a vegetative stage. In this regard, DNA barcoding could become a good alternative. In this study, 242 samples belonging to 26 species from 10 genera of aquatic plants were assessed using the chloroplast loci trnH‐psbA, matK and rbcL. Despite testing a large number of primer sets and several PCR protocols, the matK locus could not be amplified or sequenced reliably and therefore was left out of the analysis. Using the other two loci, eight invasive species could be distinguished from their respective related species, a ninth one failed to produce sequences of sufficient quality. Based on the criteria of universal application, high sequence divergence and level of species discrimination, the trnH‐psbA noncoding spacer was the best performing barcode in the aquatic plant species studied. Thus, DNA barcoding may be helpful with enforcing a ban on trade of such invasive species, such as is already in place in the Netherlands. This will become even more so once DNA barcoding would be turned into machinery routinely operable by a nonspecialist in botany and molecular genetics.     

Balamuthia mandrillaris: In Vitro Interactions with Selected Protozoa and Algae

Although Balamuthia mandrillaris was identified more than two decades ago as an agent of fatal granulomatous encephalitis in humans and other animals, little is known about its ecological niche, biological behavior in the environment, food preferences and predators, if any. When infecting humans or other animals, Balamuthia feeds on tissues; and in vitro culture, it feeds on mammalian cells (monkey kidney cells, human lung fibroblasts, and human microvascular endothelial cells). According to recent reports, it is believed that Balamuthia feeds on small amebae, for example, Acanthamoeba that are present in its ecological niche. To test this hypothesis, we associated Balamuthia on a one‐on‐one basis with selected protozoa and algae. We videotaped the behavior of Balamuthia in the presence of a potential prey, its ability to hunt and attack its food, and the time required to eat and cause damage to the target cell by direct contact. We found that B. mandrillaris ingested trophozoites of Naegleria fowleri, Naegleria gruberi, Acanthamoeba spp., Trypanosoma cruzi epimastigotes, Toxoplasma gondii tachyzoites, and Giardia. However, it did not feed on Acanthamoeba cysts or algae. Balamuthia caused cytolysis of T. cruzi epimastigotes and T. gondii tachyzoites by direct contact. Balamuthia trophozoites and cysts were, however, eaten by Paramecium sp.