Evaluation of alternative rice planthopper control by the combined action of oil-formulated Metarhizium anisopliae and low-rate buprofezin.
BACKGROUND
High resistance of brown planthopper (BPH) Nilaparvata lugens Stål to common insecticides is a challenge for control of the pest. An alternative control strategy based on the combined application of fungal and chemical agents has been evaluated.


RESULTS
Three gradient spore concentrations of oil-formulated Metarhizium anisopliae (Metschnikoff) Sorokin (Ma456) were sprayed onto third-instar nymphs in five bioassays comprising the low buprofezin rates of 0, 10, 20, 30 and 40 µg mL(-1) respectively. Fungal LC(50) after 1 week at 25 °C and 14:10 h light:dark photoperiod decreased from 386 conidia mm(-2) in the buprofezin-free bioassay to 40 at the highest chemical rate. Buprofezin (LC(50): 1647, 486 and 233 µg mL(-1) on days 2 to 4) had no significant effect on the fungal outgrowths of mycosis-killed cadavers at the low application rates. The fungal infection was found to cause 81% reduction in reproductive potential of BPH adults. In two 40 day field trials, significant planthopper (mainly BPH) control (54-60%) was achieved by biweekly sprays of two fungal candidates (Ma456 and Ma576) at 1.5 × 10(13) conidia ha(-1) and elevated to 80-83% by incorporating 30.8 g buprofezin ha(-1) into the fungal sprays.


CONCLUSIONS
The combined application of the fungal and chemical agents is a promising alternative strategy for BPH control.
Jin
Shao-Feng
SF
Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
Feng
Ming-Guang
MG
Ying
Sheng-Hua
SH
Mu
Wen-Jing
WJ
Chen
Jue-Qi
JQ
D000818:Animals; D005298:Fertility; D006430:Hemiptera / Q000382:microbiology*; D008136:Longevity; D052981:Metarhizium; D009758:Nymph; D010572:Pest Control, Biological / Q000379:methods*; D011156:Population Density; D013829:Thiadiazines
D013829:Thiadiazines; C083997:buprofezin