@article {268,
	title = {Infection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever},
	journal = {J Med Entomol},
	volume = {37},
	number = {4},
	year = {2000},
	month = {Jul},
	pages = {619-25},
	abstract = {We provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The prevalence of E. risticii was 31.9\% (n = 454 individuals) in aquatic insects (13 of 17 species were positive). Prevalence within orders was as follows: 43.5\% (n = 207) in caddisflies, 15.2\% (n = 92) in mayflies, 13.9\% (n = 115) in damselflies, 10.0\% (n = 10) in dragonflies, and 80.0\% (n = 30) in stoneflies. This study demonstrates a broad intermediate host range for trematodes that act as vector for E. risticii. Insects are likely to play an important role in the epidemiology of this disease.},
	author = {Chae, J S and Pusterla, N and Johnson, E and Derock, E and Lawler, S P and Madigan, J E}
}
@article {269,
	title = {Possible Removal of Rival Sperm by the Elongated Genitalia of the Earwig, Euborellia plebeja},
	journal = {Zoolog Sci},
	volume = {17},
	number = {5},
	year = {2000},
	month = {Jul},
	pages = {667-72},
	abstract = {Sperm displacement is a sperm competition avoidance mechanism that reduces the paternity of males that have already mated with the female. Direct anatomical sperm removal or sperm flushing is known to occur in four insect orders: Odonata, Orthoptera, Coleoptera and Hymenoptera. In a fifth order, Dermaptera (earwigs), I found that the virga (the elongated rod of the male genitalia) of Euborellia plebeja seems to be used to remove rival sperm from the spermatheca (a fine-tubed female sperm storage organ). In this species, copulation lasted on average 4.6 minutes, during which time the male inserted the virga deep into the spermatheca, and then extracted it ejaculating semen from the opening of the virgal tip. The extraction of virgae (with its brim-like tip) appeared to cause removal of stored sperm in the spermatheca. The virga was as long as the body length of males, and the spermatheca was twice the female body length. The long length of the spermatheca and the possible removal function of the virga may select for virgal elongation.},
	author = {Kamimura, Y}
}
@article {270,
	title = {A phylogenetic perspective on habitat shifts and diversity in the North American Enallagma damselflies},
	journal = {Syst Biol},
	volume = {49},
	number = {4},
	year = {2000},
	month = {Dec},
	pages = {697-712},
	abstract = {Community ecologists are increasingly aware that the regional history of taxon diversification can have an important influence on community structure. Likewise, systematists recognize that ecological context can have an important influence on the processes of speciation and extinction that create patterns of descent. We present a phylogenetic analysis of 33 species of a North American radiation of damselflies (Zygoptera: Coenagrionidae: Enallagma Selys), which have been well studied ecologically, to elucidate the evolutionary mechanisms that have contributed to differences in diversity between larval habitats (lakes with and without fish predators). Analysis of molecular variation in 842 bp of the mitochondrial cytochrome oxidase I and II subunit and of the intervening Leu-tRNA and 37 morphological characters resulted in three well-defined clades that are only partially congruent with previous phylogenetic hypotheses. Molecular and morphological data partitions were significantly incongruent (p < .01). Lack of haplotype monophyly within species and small amounts of sequence divergence (< 1\%) between related species in three of the four clades suggest that recent, and parallel, speciation has been an important source of community diversity. Reconstruction of habitat preference over the phylogeny suggests that the greater species diversity in fish-containing lake habitats reflects the recency of shifts into the fishless lake habit, although a difference in speciation or extinction rates between the two habitats is difficult to exclude as an additional mechanism.},
	author = {Brown, J M and McPeek, M A and May, M. L.}
}
@article {271,
	title = {Microsculpture of the wing surface in Odonata: evidence for cuticular wax covering},
	journal = {Arthropod Struct Dev},
	volume = {29},
	number = {2},
	year = {2000},
	month = {Apr},
	pages = {129-35},
	abstract = {The insect wing membrane is usually covered by scales, hairs, and acanthae, which serve diverse functions, such as species-specific coloration pattern, decrease of wind resistance during flight or decrease of wing wettability. Representatives of Palaeoptera (Odonata and Ephemeroptera) have no hairy structures on the wing membrane, but both its sides are fine-sculptured. In this study, the nature of the wing covering was studied using acoustic microscopy, scanning- and transmission electron microscopy followed by a variety of chemical treatments. It was shown that wing microsculptures are not cuticular outgrowths, but a wax covering, which is similar to pruinosity, which has been previously described in several odonate taxa. Data from scanning acoustic microscopy revealed that scratches on the wax covering have material density different from the surrounding material. Various functions of the wax covering are discussed.},
	author = {Gorb, S N and Kesel, A and Berger, J}
}
