ประสิทธิภาพของเชื้อราทำลายแมลงต่อเพลี้ยกระโดดสีน้ำตาลและเพลี้ยจักจั่นสีเขียว

Abstract

Efficiency of entomopathogenic fungi on the control of brown planthopper (BPH, Nilaparvata lugens) and green leafhopper (GLH, Nephotettix virescens) was studied in the laboratory and fields. Two entomopathogenic fungi, Metarhizium anisopliae was isolated from the rhinoceros beetle larva and BPH while Beauveria bassiana was isolated from BPH and the Bombay locust (Patanga succincta), respectively. These fungi were inoculated on BPH and GLH at 10**(8) conidia/ml. in the laboratory. Results showed that both M. anisopliae and B. bassiana isolated from BPH similarly affected the BPH adult (75 and 58.75 percent). The best effect on BPH nymph was obtained from M. anisopliae which was rather low being 56.25 percent. A similar trend was found for the test on GLH as M. anisopliae and B. bassiana isolated from BPH equally affected GLH adult (66.25 and 62.50 percent) However, both of them had little effect on the nymph. Results were slightly different with the field inoculation since the best effect was recorded when M. anisopliae was inoculated at 10**(6)-10**(7) conidia/ml. on BPH adult (48.33- 51.67 percent). Furthermore, the BPH nymph were similarly affected by 33.33- 50.00 percent when either M. anisopliae or B. bassiana was applied at 10**(4)- 10**(7) or 10**(6)-10**(7) conidia/ml., respectively. M. anisopliae at 10**(6)-10**(7) conidia/ml. was also most effective against 33.33-50.00 percent when either M. anisopliae or B. bassiana was applied at 10**(4)-10**(7) or 10**(6)-10**(7) GLH adult (43.33-48.33 percent). A similar trend as for the adult was observed on the GLH nymph inoculated with M. anisopliae at 10**(5)-10**(7) conidia/ml. (38.33- 45.00 percent). Integration method between the use of M. anisopliae and the other entomopathogenic fungus, Hirsutella citriformis, at 108 conidia/ml. together with 5 percent crude extract from neem (Azadirachta indica) seed and Derris elliptica revealed no additive effect on the tested insects.