Entomopathogenic fungi stimulate transgenerational wing induction in pea aphids,Acyrthosiphon pisum (Hemiptera: Aphididae)

1. Aphid natural enemies include not only predators and parasitoids but also pathogens, of which fungi are the most studied for biological control. While wing formation in aphids is induced by abiotic conditions, it is also affected by biotic interactions with their arthropod natural enemies. Wing induction via interactions with arthropod natural enemies is mediated by the increase in their physical contact when alarmed (pseudo‐crowding). Pathogenic fungi do not trigger this alarm behaviour in aphids and, therefore, no pseudo‐crowding occurs. 2. We hypothesise that, while pathogenic fungi will stimulate maternally induced wing formation, the mechanism is different and is influenced by pathogen specificity. We tested this hypothesis using two entomopathogenic fungi, Pandora neoaphidis and Beauveria bassiana, an aphid specialist and a generalist respectively, on the pea aphid, Acyrthosiphon pisum Harris. 3. We first demonstrate that pea aphids infected with either pathogen and maintained in groups on broad bean plants produced a higher proportion of winged morphs than uninfected control aphids. We then show that, when maintained in isolation, aphids infected with either pathogen also produced higher proportions of winged offspring than control aphids. There was no difference between P. neoaphidis and B. bassiana in their effects on wing induction in either experiment. 4. Unlike the effect of predators and parasitoids on pea aphid wing induction, the effect of pathogens is independent of physical contact with other aphids, suggesting that physiological cues induce wing formation in infected aphids. It is possible that aphids benefit from wing induction by escaping infected patches whilst pathogens may benefit through dispersion. Possible mechanisms of wing induction are discussed.     

Novel high‐throughput screens of Anopheles gambiae odorant receptors reveal candidate behaviour‐modifying chemicals for mosquitoes

Despite many decades of multilateral global efforts, a significant portion of the world population continues to be plagued with one or more mosquito‐vectored diseases. These include malaria and filariasis, as well as numerous arboviral‐associated illnesses, such as dengue and yellow fevers. The dynamics of disease transmission by mosquitoes is complex, and involves both vector competence and vectorial capacity. One area of intensive effort is the study of chemosensory‐driven behaviours in the malaria vector mosquito Anopheles gambiae Giles, the modulation of which is likely to provide opportunities for disease reduction. In this context, recent studies characterize a large divergent family of An. gambiae odorant receptors (AgORs) that play critical roles in olfactory signal transduction. This work facilitates high‐throughput, cell‐based calcium mobilization screens of AgOR‐expressing human embryonic kidney cells identifying a large number of conventional AgOR ligands, as well as the first nonconventional Orco (olfactory receptor co‐receptor) family agonist. As such, ligand‐mediated modulation serves as a proof‐of‐concept demonstration that AgORs represent viable targets for high‐throughput screening and for the eventual development of behaviour‐modifying olfactory compounds. Such attractants or repellents could foster malaria reduction programmes.     

Revision of the Cales noacki species complex (Hymenoptera,Chalcidoidea, Aphelinidae)

The genus Cales (Hymenoptera: Aphelinidae) includes 13 species worldwide, of which 10 form a highly morphologically uniform species complex with a native range in the Neotropical region. We recognize ten species previously attributed to a single Neotropical species, Cales noacki Howard, which in the strict sense is a species broadly disseminated to control woolly whitefly. A neotype is designated for C. noacki, and it is redescribed based on specimens molecularly determined to be conspecific with the neotype. Newly described species include: C. bicolor Mottern, n.sp ., C. breviclava Mottern, n.sp ., C. brevisensillum Mottern n.sp ., C. curvigladius Mottern, n.sp ., C. longiseta Mottern, n.sp ., C. multisensillum Mottern n.sp ., C. noyesi Mottern, n.sp ., C. parvigladius Mottern, n.sp . and C. rosei Mottern, n.sp . Species are delimited based on a combination of morphological and molecular data (28S‐D2 rDNA and COI). Additional specimens are included in the phylogenetic analyses and although these likely represent several new species, we lack sufficient specimen sampling to describe them at this time. Cales are highly morphologically conserved and character‐poor, resulting in several cryptic species. A molecular phylogeny of the known Neotropical species based on 28S‐D2–5 rDNA and a 390‐bp segment of COI is included, and identification keys to males and females are provided. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:7FEB0479‐9B2E‐48E8‐8603‐4B7C2759D4EC .     

attempted prebiotic synthesis of pseudouridine

Pseudouridine is a modified base found in all tRNA and rRNA. Hence, it is reasonable to think that pseudouridine was important in the early evolution, if not the origin, of life. Since uracil reacts rapidly with formaldehyde and other aldehydes at the C-5 position, it is plausible that pseudouridine could be synthesized in a similar way by the reaction of the C-5 of uracil with the C-1 of ribose. The determining factor is whether the ribose could react with the uracil faster than ribose decomposes. However, both rates are determined by the amount of free aldehyde in the ribose. Various plausible prebiotic reactions were investigated and none showed pseudouridine above the detection limit (<0.01%). Only unreacted uracil and ribose decomposition products could be observed. Thus the rate of addition of ribose to uracil is much slower than the decomposition of ribose under any reasonable prebiotic conditions. Unless efficient non-biological catalysts for any of these reactions exist, pseudouridine would not have been synthesized to any significant extent without the use of biologically produced enzymes.     

The phylogeny and revised classification of Machaerotidae,the tube‐making spittlebugs (Hemiptera: Auchenorrhyncha: Cercopoidea)

Machaerotidae (Hemiptera: Auchenorrhyncha: Cercopoidea) is a taxonomically small but morphologically diverse family of spittlebugs with approximately 115 described species in 31 genera and an exclusively Palaeotropical distribution. Results are presented of the first molecular phylogenetic investigation of Machaerotidae, examining relationships among the currently recognized subfamilies and tribes, as well as determining the phylogenetic placement of the genera Enderleinia Schmidt, Neuromachaerota Schmidt, Labramachaerota Bell & Cryan, and Kyphomachaerota Bell & Cryan. DNA nucleotide sequence data from eight loci (12s rDNA, 16s rDNA, 18S rDNA, 28S rDNA, histone 2A, histone 3, wingless and NADH Dehydrogenase subunit 4) were analysed to reconstruct the phylogeny. The evidence generated in this study supports the following systematic conclusions: (i) Machaerotidae is a monophyletic family; (ii) Machaerotini, Hindoloidini (with the new inclusion of Kyphomachaerota), and Enderleiniini (excluding Kyphomachaerota and Apomachaerota Schmidt) are monophyletic tribes; (iii) the genus Apomachaerota was recovered as the most anciently diverged lineage of extant Machaerotidae, and a new subfamily (Apomachaerotinae subfam.n. ), is proposed on the basis of its phylogenetic placement as sister lineage to all other extant Machaerotidae.     

Cales (Hymenoptera: Chalcidoidea): morphology of an enigmatic taxon with a review of species

Calesinae is a small group of Chalcidoidea (Hymenoptera) that are parasitoids of whiteflies (Hemiptera: Aleyrodidae). One species, Cales noacki Howard, has been introduced from South America into citrus‐growing regions of North America, the Mediterranean and Africa for biological control. The remaining species are found in Australia and New Zealand: a classic Gondwanan disjunction. The subfamily consists of a single genus, Cales, which is currently unplaced within Chalcidoidea. Its taxonomic position has historically been unstable, although most often Cales is associated with Aphelinidae. Here, we present a detailed morphological study of the group with an emphasis on Australian species. Although Cales shares many characteristics with Aphelinidae, especially Coccophaginae and Eretmocerus, more studies of character systems across Chalcidoidea are needed to determine which features may be synapomorphic. Consequently, we leave Cales incertae sedis within Chalcidoidea. We also describe a new species from New Zealand, Cales berryi sp.n. , reared from the whitefly Asterochiton pittospori on lemonwood, Pittosporum eugenioides, and we present a key and review the four known species of Cales.     

Long-Term Persistence of Spent Lead Shot in Tundra Wetlands

ABSTRACT We seeded experimental plots with number 4 lead pellets and sampled these plots for 10 years to assess the settlement rate of pellets in tundra wetland types commonly used by foraging waterfowl. After 10 years, about 10% of pellets remained within 6 cm of the surface, but >50% remained within 10 cm. We predict that spent lead pellets will eventually become unavailable to waterfowl; however, it will likely require >25 years for all pellets to exceed depths at which waterfowl species may forage.     

Neural activation of the sex-pheromone gland in the moth Manduca sexta: real-time measurement of pheromone release

Abstract. Investigations of various species of moths have suggested that the biosynthesis of sex pheromone in the abdominal pheromone glands of females may be at least partly regulated by neuroendocrine mechanisms. Few studies, however, have explored the mechanisms underlying the release of sex pheromone. In experiments on the sphinx moth Manduca sexta (L.) (Lepidoptera: Sphingidae), we have monitored the time course of sex-pheromone release in scotophase females with the aid of an electroantennogram bioassay based on the highly sensitive and selective sex-pheromone receptor neurones of the male antenna. Pheromone release was evoked by orthodromic stimulation of the ventral nerve cord. Neurally stimulated release occurred with a subsecond latency and did not depend on bioactive factors in the haemolymph or on movement of the abdomen or the ovipositor. Severing the most medial pair of nerves posterior to the terminal abdominal ganglion (the terminal nerves) eliminated pheromone release, but not abdominal contractions. Release was also inhibited reversibly if the descending Ca²⁺-dependent synaptic input to the terminal ganglion was blocked by exposure to elevated concentrations of Mg²⁺. These findings indicate that the release of sex pheromone from the pheromone gland in female M. sexta is a true neuroeffector response and that the gland appears to be controlled by neurones that project to it from the terminal abdominal ganglion.     

Tip Transformation in Tetrahymena: A Morphogenetic Response to Interactions Between Mating Types*

SYNOPSIS. In Tetrahymena thermophila subline B, a morphogenic alteration of the anterior end of cells of mating types III and VII results from a cellular interaction which precedes and is a prerequisite for pairing. Cell pairing begins 1 h after starved cells of complementary mating type are mixed. The 1 h-long lag period is characterized by an actinomycin D-sensitive inductive interaction in the first 30 min, followed by a maturation period. Tip transformation begins during the maturation period and continues after pairing. Scanning electron microscopy of deciliated cells reveals ridges which form a chevron meeting in a midline seam between the oral apparatus and the anterior tip. During transformation, the seam broadens until the ridged surface is completely smooth. Melding of the ridges also occurs at the tip of the cell resulting in its blunted appearance. Cells of complementary mating types join in the region of this modified surface, which eventually becomes a specialized cell junction perforated by cytoplasmic bridges. Thus, pursuant to an inductive interaction the structure of the tip of cells is modified in anticipation of the pairing event. Rate of cell pairing might be limited by rate of tip transformation.