Conservation Biological Control Strategies Research Articles

Assessment of aphid host range and isolate variability in Pandora neoaphidis (Zygomycetes: Entomophthorales)

A three tiered assay system was devised for comparing isolates of Pandora neoaphidis against seven UK pest aphid species; Acyrthosiphon pisum , Aphis fabae , Brevicoryne brassicae , Myzus persicae , Metopolophium dirhodum , Sitobion avenae , and Rhopalosiphum padi . In Tier 1, 20 P. neoaphidis isolates were screened against all seven species, and 16 fungal isolates gave moderate to high infections of 40–100%. A. pisum was most susceptible whereas R. padi was least susceptible to infection. In Tier 2, isolates NW 314, NW 316, and NW 327 were used in concentration-response assays against A. pisum , M. dirhodum , and M. persicae . Probit analysis produced median lethal concentrations (LC 50 ) of 8–105 conidia mm −2 for A. pisum , 38–92 conidia mm −2 for M. dirhodum and 105–626 mm −2 for M. persicae . In Tier 3 bioassays, LC 50 values for the three isolates were tested as discrimatory concentrations against A. fabae , B. brassicae , R. padi , S. avenae , with M. persicae as the reference species. Logistic regression analysis indicated that B. brassicae and R. padi were less susceptible to infection than four other aphid species. The overall ranking of aphids to infection by P. neoaphidis was: A. pisum > A. fabae , M. dirhodum , M. persicae , S. avenae > B. brassicae , R. padi . The results suggest that P. neoaphidis can cross-infect aphid species which occur both in field crops and non-cropped areas, such as field margins. This is an important feature for the development of conservation biological control strategies.