D. Moore et al., LONG-TERM STORAGE OF METARHIZIUM FLAVOVIRIDE CONIDIA IN OIL FORMULATIONS FOR THE CONTROL OF LOCUSTS AND GRASSHOPPERS, Biocontrol science and technology, 5(2), 1995, pp. 193-199
Freshly harvested conidia of Metarhizium flavoviride (Gams & Rozsypal)
were stored in two vegetable oils, groundnut oi soya, or a miner-al o
il, Edelex. They were diluted with either Shellsol K or deodorized ker
osene, and antioxidants were added to half of the vegetable oil formul
ations. Dried non-indicating silica gel was added to half of the formu
lations before storage at 8 or 17 degrees C. Undried conidia, those wi
thout silica gel. lost viability rapidly with germination dropping bel
ow 40% after 9 and 32 weeks at 17 and 8 degrees C respectively. After
127 weeks (ca. 30 months) in storage, germination remained at over 60
and 80% for the dried formulations at 17 and 8 degrees C respectively
(after an unexplained drop in germination after 16-18 months in storag
e). Comparable figures for 160 weeks (ca. 37 months) were 47 and 68%.
These figures represented germination after 24 h of incubation; after
48 h of incubation, germination was 79 and 89% from samples stored for
160 weeks at 17 and 8 degrees C respectively. Representative formulat
ions of the stored conidia were tested in bioassays against the desert
locust Schistocerca gregaria (Forskal) up to 30 months into the exper
iment, and were Sound to have retained full virulence compared with fr
eshly prepared formulations.