[Comparative susceptibility of Myzus persicae to 16 strains of Metarhizium spp. from different host insects and geographic regions].
The fungal biocontrol agents Metarhizium species and varieties have been widely applied for insect control but their targets rarely aim at sucking-type homopteran insects such as aphids. To search for fungal candidates against aphids, 16 strains of four varieties of two Metarhizium species, most of which originally infected foliage insect pests in Asia, Africa and America, were bioassayed to compare their virulence to Myzus persicae apterae. With each strain, each of three conidial suspensions was sprayed onto aphids in three Petri dishes (about 40 aphids per dish) in a Potter Spray Tower, resulting in deposits of conidia for low, medium and high dosage treatments (no. conidia/mm2). After spray, all aphids were reared at the regime of 25 +/- 1 degree C and 12:12 L:D and observed daily for counts of mycosed cadavers. As a result, 10 strains of M. anisopliae (Ma) and M. anisopliae var. anisopliae (Maa) caused 67%-100% mortalities at the high dosage of about 1000 conidia/mm2 within 7 days after spray whereas other strains, including M. anisopliae var. majus, M. anisopliae var. acridum, M. flavoviride var. minus, killed a very small number of aphids even at the high conidial dosage. Of the 10 strains, Ma 456 and Maa 3332 were highly virulent to the aphid species based the modeling of their time-dose-mortality data. The LC50 of the two strains were estimated as 113 and 260 conidia/mm2 on day 4, 32 and 43 conidia/mm2 on day 5, 17 and 26 conidia/mm2 on day 6, and only 11.4 and 19.9 conidia/mm2 on day 7, respectively. Thus, both strains are highly potential for use in microbial control of aphids.
Shan
Le-tian
LT
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Feng
Ming-guang
MG
D000818:Animals; D001042:Aphids / Q000382:microbiology*; D007313:Insecta / Q000382:microbiology*; D052981:Metarhizium / Q000472:pathogenicity*; D010572:Pest Control, Biological / Q000379:methods*