Entomopathogenic fungi, such as Metarhizium anisopliae and Beauveria bassiana, have been shown to be efficacious in killing mosquito larvae of different mosquito species. The current study compared the pathogenicity and efficacy of two formulations of three fungal strains against different instars of three mosquito species with the aim of identifying the most virulent strain for use under field conditions. Three strains of Metarhizium, ARESF 4556, ARSEF 3297 and V275, were assayed against early (L 2−3 ) and late (L 3-4 ) instar larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. Two formulations of the fungi were tested, dry conidia and aqueous suspensions (i.e. 'wet' conidia). Effects of all combinations of conidia, mosquito species, instar, fungal strain and concentration on mosquito mortality were analysed using Cox regression and Kaplan-Meier analyses. Strain ARSEF 4556 was more virulent than ARSEF 3297 and V275, with LT 50 values ranging from 0.3 to 1.1 days, with Anopheles and Culex being more susceptible than Aedes. Early and late instars were equally susceptible independent of species. Although the formulation did influence mortality rates, both 'wet' and 'dry' conidia applications were highly effective in killing mosquito larvae. Viable spores were more efficacious than heat killed spores. The latter did cause mortality but only at high concentrations. Metarhizium sp. has proved to be effective in reducing survivability of all larval stages of Aedes, Anopheles and Culex under laboratory conditions. Aedes larvae were generally more tolerant than Anopheles and Culex irrespective of fungal strain.

Dothistroma septosporum is a serious foliar pathogen of pines in Britain. To determine the contribution of spores produced on abscised needles to the D. septosporum inoculum load in a forest environment, survival of the fungus was investigated in commercially grown plantations of Corsican pine (Pinus nigra subsp. laricio) in southern England. The fungus persisted for longer in abscised needles retained in the canopy compared with needles on the litter layer of the forest floor. High relative humidity had a significant negative effect on persistence in the canopy needles, highlighting the effect of moisture on rates of microbial decay. The median lethal time 50 (LT50) of infective propagules from needles in the litter layer was 20 to 28 days, whereas for needles suspended in the canopy it was 34 to 48 days. Microsatellite markers revealed that the population of D. septosporum deemed persistent (i.e., recovered from abscised needles after exposure for 28 to 32 weeks) was similar to the general population of D. septosporum in the forest stand (i.e., isolates recovered from attached needles and after exposure for only 4 weeks). Overall, abscised needles with acervuli of D. septosporum contribute only moderately and for a limited time to inoculum levels of the pathogen in an infected forest stand.