Temperature modulates the effects of predation and competition on mosquito larvae

1. Predation risk affects interspecific competition by decreasing foraging activity and relative competitive ability. Predation risk is determined by predators' prey choice and prey responses, both of which can be influenced by temperature. Temperature is especially important for larval prey and can result in a trade‐off between predator‐induced decreases in foraging activity and growth. Interspecific competition must also be examined in relation to intraspecific density‐dependent competition; weaker interspecific competition leads to coexistence of competitors. 2. This study explored how temperature (15 and 25 °C) could affect a focal species, larvae of the mosquito Culex quinquefasciatus, by examining prey choice in a shared predator (mosquitofish; Gambusia holbrooki) and the effects of predation risk on interspecific competition with Limnodynastes peronii tadpoles. Intraspecific density‐dependent competition in C. quinquefasciatus at these temperatures was also examined. 3. At 25 °C, G. holbrooki consumption of both C. quinquefasciatus and L. peronii increased; however, the effects of interspecific competition on mosquito survival did not decrease with L. peronii exposure to predation risk. The relationship between intraspecific density‐dependent competition and interspecific competition was temperature‐dependent, with competitive dominance of L. peronii at 25 °C. Male and female mosquitoes had different temperature‐dependent responses, indicating sex‐specific intrinsic responses to starvation and differential selection pressures. At 25 °C, females were susceptible to interspecific competition by L. peronii, while males were susceptible to intraspecific competition. 4. The use of competitors as biological controls has implications for mosquito disease transmission, and these results suggest that control effectiveness may be modified by climate change.     

Phylogenetic relationships within the genus Cranothrips (Thysanoptera,Melanthripidae) with consideration of host associations and disjunct distributions within the family

Abstract A phylogenetic analysis of the Melanthripidae genus Cranothrips Bagnall is presented. A data matrix with continuous and discrete characters was analysed under parsimony criteria. Continuous and discrete characters were analysed, separately and in combination. When the different blocks of characters were analysed separately, important differences in tree topologies occurred. The optimal tree obtained from discrete characters alone was similar to the tree resulting from total evidence. For most groups, the support values resulting from all the evidence analysis were higher than those obtained from the discrete‐only analysis. Two new species from Australia are described and illustrated, Cranothrips ibisca sp.n. and Cranothrips conostylus sp.n. A key to the 12 species in the genus is provided. Additionally, the host associations and the distributional patterns of the four worldwide genera of Melanthripidae are discussed.     

Ten species specific microsatellite loci for Lahontan cutthroat trout,Oncorhynchus clarki henshawi

Ten polymorphic microsatellite loci (containing tri and tetra‐nucleotide repeats) were developed for the Lahontan cutthroat trout (Oncorhynchus clarki henshawi), a subspecies of cutthroat trout listed as threatened under the United States Endangered Species Act. Polymorphism was assessed for 445 individuals from 12 populations representing eight watersheds spread throughout the three Distinct Population Segments defined for this subspecies. All loci were polymorphic (X? = 19, range 7–26 alleles). All loci were in Hardy–Weinberg equilibrium (HWE) except for one locus (OCH 9) in a single population (P < 0.00014 after Bonferroni correction for multiple tests).     

Influence of male mating history on female reproductive success among monandrous Naryciinae (Lepidoptera: Psychidae)

1. Multiple male copulations can have detrimental effects on female fitness due to sperm limitation. 2. Monandrous Naryciinae females are immobile while the males are short‐lived and do not feed. Multiple male mating is therefore expected to lead to sperm limitation in females. Sperm limitation and male limitation are hypothesised as causes of the repeated evolution of parthenogenetic reproduction in the Psychidae. 3. In this study, the effects of multiple male mating on female reproduction are investigated in several species of Naryciinae by allowing males multiple copulations. The results for two species, Siederia listerella and Dahlica lichenella, are compared. The sex ratios of 53 natural populations are examined for indications of male limitation. 4. Previous copulations by the male increased the female's risk of remaining unfertilised. However, contrary to expectations, those unfertilised females were capable of successful re‐mating. 5. In S. listerella, the number of previous copulations of males negatively influenced female fitness. Females produced 30% fewer offspring if they mated with a previously mated male. In D. lichenella, the older the male and the lower its number of total lifetime copulations, the higher the female's reproductive success. 6. Only a fraction of the investigated populations had a female‐skewed sex ratio, but differences in development time between males and females could lead to reproductive asynchrony. 7. In conclusion, male mating history did not lead to strong sperm limitation in Naryciinae as had been suggested by their life history.     

A field experiment in Ghana on the tolerance of cocoa seedlings to cocoa swollen-shoot and cocoa mottle-leaf viruses

Seedings of Amelonado Cocoa and of two progenies obtained by crossing Iquitos (Upper Amazon) parents were infected with three strains of cocoa swollen-shoot virus (CSSV) and with cocoa mottle-leaf virus (CMLV). CSSV strain I A had the most severe effects on the growth and canopy condition of all varieties. All four virus isolates had more effect on the growth of Amelonado than on the Iquitos progenies, except that CSSV strain I W affected the growth of Amelonado and one of the Iquitos progenies equally, as did CMLV which caused the greatest decrease in the first crop of all varieties. The relative virulence of different CSSV strains in any one variety can be assessed from single criteria such as length of latent period or effect on growth; CMLV had a shorter latent period than CSSV Strain I A but less effect on growth.     

Phylogenetic relationships within the genus Desmothrips (Thysanoptera,Aeolothripidae), an Australian genus of facultative flower‐living predators

A phylogenetic analysis of the Australian Aeolothripidae genus Desmothrips Hood is presented. A data matrix with 27 species is analysed under parsimony criteria. The monophyly of Desmothrips is recovered. Continuous and discrete characters were analysed separately and in combination, and continuous characters were rescaled and analysed under equal weights. Three new species from the northwestern and one from the southeastern areas of Australia are described and illustrated. A key to the 18 species of Desmothrips is provided.     

Characterization of microsatellite markers for the tanoak tree,Lithocarpus densiflorus

We describe the development of 19 primers for amplification of microsatellite loci for tanoak, Lithocarpus densiflorus (Hook. & Arn.). A population from Soquel State Demonstration Forest, Santa Cruz County, California (n = 20), and eight individuals from four additional coastal populations and one interior (Sierra Nevada) population were used to investigate polymorphism. The total number of alleles per locus ranged from two to 10. Observed heterozygosity in the Soquel population ranged from 0.05 to 0.70, with two loci being fixed.     

The Effect of Air Humidity on Photosynthesis of Ryegrass and White Clover at Three Temperatures

Increasing leaf-air vapour pressure deficit (VPD) decreasedthe stomatal conductance and the photosynthetic rate of leavesof ryegrass (Lolium perenne L.) and white clover (Trifolhimrepens L.) at light saturation and at lower irradiance. In ryegrassboth conductance and photosynthesis, and in clover photosynthesis,decreased less with increasing VPD in low irradiance than theydid at an irradiance which saturated photosynthesis. In ryegrass,relative to their values at 10 mb, photosynthesis and conductancedecreased less with increasing VPD at 25 °C than at 20 or16·5 °C. In white clover, relative conductance (butnot photosynthesis) was less reduced at 25 than at 16·5°C Measurements of VPD of air in the leaf canopy of a field-growncrop are combined with the observed responses of photosynthesisto VPD and temperature in a model. This shows that high VPDis likely to depress photosynthesis significantly and that,during a typical day, the rate of light saturated photosynthesismay remain fairly steady, because the depression of photosynthesisdue to rising VPD is offset by the stimulation due to risingtemperature Perennial ryegrass, Lolium perenne L., White clover, Trifolhim repens L., photosynthesis, leaf conductance, water vapour pressure deficit, temperature