The relationship between daily routines of singing and foraging: an experiment on captive Great Tits Parus major

Unpaired, singing, male Great Tits Parus major kept in aviaries were subjected to two different daily regimes of foraging profitability. Birds learnt to adjust their foraging patterns to avoid feeding at periods of low foraging profitability. Once learnt, this had no effect on their singing regimes, indicating no direct causal link between the organization of daily regimes of singing and foraging. When first faced with low foraging profitability early in the morning, birds reduced morning song levels but these returned to normal, although no higher than normal, as they learnt to anticipate the daily routine. This suggests that unpredictable periods of low foraging profitability cause reduced singing activity but predictable time of day effects do not. Birds did not spend all their non-foraging time singing and appeared to have 'free time'.     

Sequence analysis of the mitochondrial DNA control region of ciscoes (genus Coregonus): taxonomic implications for the Great Lakes species flock

Sequence variation in the control region (D-loop) of the mitochondrial DNA (mtDNA) was examined to assess the genetic distinctiveness of the shortjaw cisco ( Coregonus zenithicus ). Individuals from within the Great Lakes Basin as well as inland lakes outside the basin were sampled. DNA fragments containing the entire D-loop were amplified by PCR from specimens of C. zenithicus and the related species C. artedi , C. hoyi , C. kiyi , and C. clupeaformis . DNA sequence analysis revealed high similarity within and among species and shared polymorphism for length variants. Based on this analysis, the shortjaw cisco is not genetically distinct from other cisco species.     

A Comparative Study of Lipid Compositions of Cryptosporidium parvum (Apicomplexa) and Madin-Darby Bovine Kidney Cells

Membrane lipid compositions of Cryptosporidium parvum and Madin-Darby bovine kidney cells, an epithelial-like cell line commonly used to study coccidia in vitro, were analyzed using both thin-layer chromatography and gas-liquid chromatography. Phosphatidylcholine was the predominant lipid in both C. parvum and Madin-Darby bovine kidney cells, comprising 65% and 41% of the total phospholipids, respectively. Phospholipids of C. parvum contained twice the level of 16:0 and twenty-fold more 18:2 than the Madin-Darby bovine kidney cell line. We suggest that the parasite may be capable of sequestering specific complex membrane lipids at concentrations greater than those in the host cells. This study constitutes the first report of the lipid composition of C. parvum .     

Characterization of Mouse Pmel 17 Gene and Silver Locus

Pmel 17 cDNA clones, isolated from wild-type and si/si murine melanocytes, were sequenced and compared. A single nucleotide (A) insertion was found in the putative cytoplasmic tail of the si/si Pmel 17 cDNA clone. This insertion is predicted to alter the last 24 amino acids at the C-terminus and to extend the Pmel 17 protein by 12 residues. The mutation was confirmed by the sequence of the PCR-amplified genomic region including the mutation site. Silver Pmel 17 was not recognized by antibodies directed toward the C-terminal amino acids of wild-type Pmel 17, indicating a defect in this region. These results indicate that silver Pmel 17 protein has a major defect at the carboxyl terminus.     

Monocaryotization of Cultures of Lenzites trabea (Pers.) Fr. and other Wood-destroying Basidiomycetes

Cultures of Lenzites trabea and some other basidiomycetes grownon nutrient agar containing high concentrations of sodium arsenateconsistently reverted from the dicaryotic to the monocaryoticcondition. This effect could also be induced by a wide varietyof other toxicants, including copper sulphate, zinc sulphate,sodium dichromate, sodium pentachlorophenate, creosote, crystalviolet, boric acid, and sodium taurocholate, but sodium arsenatewas the most reliable monocaryotizing agent, being effectivewith eight of the fourteen basidio-mycete species tested withit. The neohaplonts formed by sodium arsenate and other toxicantsmate normally with each other and with compatible monosporeisolates. The value of chemical monocaryotization as a techniquein fungal genetics and experimental taxonomy is discussed. Byusing the mating factor alleles as genetic markers, it was demonstratedthat when L. trabea is monocaryo-tized by sodium arsenate orcopper sulphate, only one of the two nuclei in the dicaryoncan be recovered in the neohaplonts, the direction of this completenuclear selection depending on the toxicant and the dicaryonconcerned. It was shown to occur in treated wood blocks duringroutine soil-block decay tests of inorganic wood preservativesand it is probably a frequent, though hitherto unrecognized,occurrence in the laboratory testing of wood preservatives andother fungicides against basidiomycetes.     

THE FUNGICIDAL CONTROL OF LETTUCE DOWNY MILDEW, CAUSED BY BREMIA LACTUCAE

Protection experiments carried out in the greenhouse showed that preparations of thiram, zineb, ferbam and ziram were superior to cuprous oxide and copper oxy-chloride preparations, in controlling downy mildew of lettuce and in lack of phytotoxic effect.
Tests made in winter on lettuce seedlings grown in Dutch lights, showed that Bremia lactucae attack reduced the stand of seedlings, diminished their size and weight, and, when the crop was planted out into the open ground, reduced survival in the field and slightly delayed the date of reaching maturity. The best overall results in protecting foliage against downy mildew were given by thiram and zineb preparations.     

Sublethal effect of brood parasitism on the grass-carrying wasp Isodontia mexicana

Abstract.  1. The nests of solitary, nest-provisioning wasps (Sphecidae and Crabronidae) are commonly attacked by brood parasites, including flies of the families Phoridae and Sarcophagidae. Larvae of the flies commonly kill the wasp offspring directly or starve it by consuming prey provided by the adult female wasps.
2. To determine whether brood parasitic flies can have a sublethal effect (i.e. reduced body size) on wasp offspring, nests of the wasp Isodontia mexicana were collected at two field sites in upstate New York, U.S.A. Nest diameter had no effect on the probability that a wasp cell would be inhabited by a brood parasite. Most offspring that developed in cells also containing phorids or sarcophagids managed to complete development and emerge as adults. Nevertheless, they had significantly smaller body size than conspecifics emerging from unparasitised cells in which the developing wasp did not have to compete for food (which in this species consists of tree crickets and katydids). Apparently, this is the first time that a sublethal effect of brood parasitism on offspring body size has been quantified for a solitary wasp species. Known effects of body size on the reproductive success of adult wasps suggest that sublethal consequences of the presence of brood parasites may have a significant effect on the fitness of adult I. mexicana .     

Intra‐specific host preference for Littoraria filosa by the dipteran parasitoid Sarcophaga megafilosia: the consequences of attacking individuals outside the preferred size range

1. The marine snail, Littoraria filosa, lives on the leaves and trunks of mangroves. Populations of L. filosa are annual when its dipteran parasitoid Sarcophaga megafilosia is present, but perennial in its absence. 2. The size distribution of naturally occurring parasitised L. filosa suggests S. megafilosia has a distinct preference for snails with shells ≥ 10 mm long but, paradoxically, most individuals ≥ 18 mm long disappear from annual populations in late spring/early summer without appearing in the parasitised cohort. 3. When S. megafilosia was offered an unrestricted size range of L. filosa, only individuals >10 mm long were attacked and those from 19 to 20 mm long were preferred. 4. In no‐choice experiments, L. filosa <10 mm long were parasitised but pupation did not occur. For L. filosa >23 mm long, most attacked snails succeeded in ejecting the parasitoid larva but often lost their grip on the wall or ceiling of the cage and fell. Littoraria filosa is unlikely to survive such dislodgement from mangrove trees. 5. These results can explain the different size distributions of live and parasitised snails in the field, including the disappearance of large snails that do not subsequently appear in the parasitised cohort. However, this does not explain the preference by S. megafilosia for L. filosa around 19–20 mm for which more than 50% of attacks failed. This preference may be also determined by increased parasitoid fecundity and longevity as snail size increases. 6. If small differences in host size affect parasitoid fitness, it may help explain why attempts at biological control using known parasitoids of an exotic species are often ineffective or unsuccessful.