Glugea gasti sp. n., a Microspridan Pathogen of the Boll Weevil Anthonomus grandis1,2,3

SYNOPSIS. Glugea gasti sp. n., a microsporidan pathogen of Anthonomus grandis Boheman (the boll weevil), is described and a probable life cycle presented. The alimentary canal, and probably the mesenteron 1st, is the initial site of infection, altho the disease later becomes generalized thruout most body tissues. Binucleate sporoplasms initiate the 1st schizogonic phase, characterized by mono- and bi-nucleate schizonts. The 2nd schizogonic phase is characterized by mono-, bi- and quadrinucleate schizonts, by prolific multiplication, by the dense compact nuclei early in this phase, and late in this phase by larger schizonts with less dense vesicular nuclei. This phase terminates in formation of diplokarya. The sporogonic phase is characterized by combination of the 2 nuclei in the diplokaryon followed by nuclear divisions in a sequence closely resembling meiosis. Two sporoblasts are produced from each sporont. Mature spores in wet mounts by phase contrast were 4.3 ± 0.3 μ long by 2.3 ± 0.2 μ wide. The polar filament averaged 76 μ long. Mature spores were present about 24 hours after infection. Some observations are presented on an external filament extending from one pole of the spore to host tissue and other events during the process of spore morphogenesis.     

Fitness traits of insecticide resistant and susceptible strains of tea mosquito bug Helopeltis theivora Waterhouse (Heteroptera: Miridae)

We compared the biological traits of insecticide resistant and susceptible field populations of tea mosquito bug Helopeltis theivora Waterhouse. The insecticide resistant population of the conventional Tea Estate “Chuapara” of the Dooars, Jalpaiguri, differed significantly from the susceptible strain of the organic Tea Estate “Makibari” of Darjeeling. Both these tea plantation areas are located in the northern part of West Bengal, India. Adverse changes in biological and developmental traits were observed mainly in: (i) reduction in oviposition period; (ii) fecundity; and (iii) prolongation of nymphal and total developmental period. However, all other parameters such as pre- and post oviposition periods, egg incubation period, hatchability and adult longevity were not significantly different. These results clearly demonstrated that only certain fitness components in the resistant strains appear to be adaptively changed and lowered.     

'Floral' scent production by Puccinia rust fungi that mimic flowers

Crucifers (Brassicaceae) in 11 genera are often infected by rust fungi in the Puccinia monoica complex. Infection causes a 'pseudoflower' to form that is important for attracting insect visitors that sexually outcross the fungus. 'Pollinator' attraction is accomplished through visual floral mimicry, the presence of a nectar reward and floral fragrances. Here we used gas chromatography and mass spectrometry to identify and quantify fragrance production by these rust fungi on several Arabis hosts, and by co-occurring true flowers that share insect visitors. Fungal pseudoflowers produced distinctive floral fragrances composed primarily of aromatic alcohols, aldehydes and esters. Pseudoflower fragrances were chemically similar to noctuid-moth-pollinated flowers, such as Cestrum nocturnum and Abelia grandiflora , but were very different from host flowers, host vegetation and the flowers of coblooming, nonhost angiosperms. There was variation in the quantity and composition of fragrance profiles from different fungal species as well as within and among hosts. The evolution of scent chemistry is relatively conservative in these fungi and can be most parsimoniously explained in three steps by combining chemical data with a previously determined rDNA ITS sequence-based phylogeny. Pseudoflower scent does not appear to represent a simple modification of host floral or vegetative emissions, nor does it mimic the scent of coblooming flowers. Instead, we suspect that the unique fragrances, beyond their function as pollinator attractants, may be important in reducing gamete loss by reinforcing constancy among foraging insects.     

Clitellate cocoons in freshwater deposits since the Triassic

Previously enigmatic, ovoid to sac-like fossils of organic, acid resistant substance which are common components of leaf cuticle and megaspore assemblages in limnic and terrestrial palaeoen- vironments are identified as cocoons of clitellates. They have been recorded for a long time by palaeobotanists and palynologists, particularly in the Mesozoic, and have been variously interpreted as being of megaspore, seed, or algal origins, although convincing homologues were lacking. The fossils agree in basic wall construction with cocoons of clitellates, and particularly with certain members of the Hirudinea. A clitellate affinity is further supported by a possible segmentation, their consistently non-marine occurrence, evidence for predation, and an example of amber-like inclusion of alien structures in the cocoon wall which indicates the presence of secretion. As a consequence of the new interpretation, two taxa established under the botanical code of nomenclature for such fossils, namely Burejospermum crassitestum Krassilov and Dictyoth- ylakos pesslerae Horst, are transferred to the zoological kingdom and classified under Clitellata (phylum Annelida), along with two new taxa, D. spitsbergensis sp.n. and Pilothylakospilosus gen. et sp.n. With the present interpretation a consistent Mesozoic record is documented for clitellates, a group of softbodied, basically freshwater and terrestrial animals of which there was until now nearly no fossil record.     

Isolation and characterization of microsatellite markers in Labiotermes labralis (Isoptera,Termitidae, Nasutitermitinae)

We report here on the development of six polymorphic microsatellite loci for Labiotermes labralis. This soil‐feeding species is restricted to the Neotropical rainforest and then could represent a major candidate for being a bio‐indicator of anthropic disturbance resulting in the forest fragmentation. The microsatellite loci were isolated and characterized using a microsatellite‐enriched genomic library. The primers were tested on a French Guyanese population of L. labralis, represented by the sampling of one soldier in 22 nests. The primers were also tested against nine species of the same Nasutitermitinae subfamily and were successfully amplified at five loci in Armitermes minutus.     

Bacterial microbiota associated with ants of the genus Tetraponera

Tropical arboreal ants mainly feed as 'secondary herbivores', relying mostly on nitrogen-poor homopteran exudates as food. It has been speculated that this nitrogen-limitation of their diet may be overcome by nutritional upgrading with the help of symbiotic bacteria. We examined the bacterial diversity associated with several representatives of three species groups of the arboreal ant genus Tetraponera based on genes encoding 16S rRNA, citrate synthase and a structural protein of the dinitrogenase complex ( nifH ). The bacterial microflora showed group-specificity, suggesting long-term association between ants and bacteria. In all specimens of four species of the nigra group, we detected bacteria closely related to Bartonella (order Rhizobiales). Ants of the allaborans group harboured bacteria belonging to the enterobacteria. In Tetraponera pilosa of the third species group, we found the enterobacterium Pantoea agglomerans . In spite of the different phylogenetic affiliation of the bacteria identified in the three species groups, the presence of nifH in most species suggests a role in nitrogen metabolism of the bacterial microbiota. We also detected a high infection rate with the intracellular bacterium Wolbachia in all Tetraponera species groups. Besides the widespread bacteria found in Tetraponera , we discovered a diverse group of bacteria represented by single sequences. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 399–412.     

Production of Phytophthora infestans oospores in planta and inoculum potential of in vitro produced oospores under temperate highlands and subtropical plains of India

High moisture content of the host tissue ( 88%) and low ambient r.h. (50-54%) favoured oospore formation under controlled environments. It took 14–16 days for oospores to develop; thereafter the number of oospores increased with time and decreased with moisture content of host tissue. High ambient r.h. (> 80%) did not favour oospore formation under field or controlled conditions. Oospore formation was detected in inoculated plants grown in the field when the ambient r.h. declined to 74% and moisture content of host tissue decreased to 83.7–85.6%. It took 8 days (cv. Kufri Chandramukhi) to 13 days (cv. Kufri Jyoti and Kufri Badshah) for oospores to develop. Cultivars also differed in their response to oospore production, cv. Kufri Chandramukhi being more responsive (4800 oospores g⁻¹ f wt) than cv. Kufri Jyoti and Kufri Badshah (1320 and 390 oospores g⁻¹ f wt respectively). Oospores produced in vitro remained viable when buried in soil in the temperate highlands of Himachal Pradesh and sub-tropical plains of Uttar Pradesh, India for more than 150 days, i.e. beginning of the next crop season. The oospores germinated and initiated late blight infection at the base of the stems after 21–30 days of incubation of the potato plants raised in oospore-infested soil. It took 2 days for newly formed oospores to germinate and this delay time increased to 75–77 days after 180-days burial. It took 15 days for their germination (47%) in soil extract as compared to 50 days in sterilised distilled water.