Abstract: 【Aim】 Cladiucha huangbki is a newly identified sawfly of Cladiucha of Tenthredinidae. Its larvae feed on leaves of Manglietia yuyuanensis with large population density and cause serious damage. This study aims to clarify the biological characteristics 
of C. huangbki and screen out the high pathogenicity strains of Metarhizium anisopliae against this sawfly, so as to provide theoretical basis and strain resources for the biological control of this insect pest. 【Methods】 The morphological and biological characteristics of various developmental stages of C. huangbki including host plants, distribution, and life history were observed in both the laboratory and field. High pathogenic strains of M. anisopliae against this insect pest were screened by using spraying spore suspension. 【Results】 The results of field and laboratory observations showed that C. huangbki larvae feed on Manglietia plants of Magnoliaceae. C. huangbki has only one generation each year in Yong′an City, Fujian Province. Mature larvae (prepupae) oversummer and overwinter in the soil chamber and start to pupate in early March of the next year. Adults begin to emerge in late March, and female adults reach the oviposition peak in early April. Larvae are hatched in mid-April and cause enormous damage in late April to early May. Mature larvae burrow into soil in the depth of 30-150 mm to make soil chambers in mid-May. The results of pathogenicity test showed that the corrected mortality rates of C. huangbki caused by the suspension of all the tested strains of M. anisopliae at 
the concentration of 1×10⁷ spores/mL were over 85% at 11 d post inoculation, and the strains MaQZ-01, MaYTTR-04-05, Ma3 and MaFZ-13 caused the larval corrected mortality rates of 100%. The strain MaFZ-08 caused the highest cadaver rate of C. huangbki (60%), followed by MaYTTR-04-05, causing the cadaver rate of 50%. The median lethal time (LT₅₀) values of various strains of M. anisopliae to C. huangbki larvae were about 6 d, showing little difference between different strains, while the LT₅₀ value of MaYTTR-04-05 to C. huangbki larvae was the shortest, being 5.090 d.【Conclusion】 C. huangbki has only one generation each year in Yong′an, Fujian, and mature larvae burrow into soil to make soil chambers for oversummering and overwintering of prepupae after early-May. The strain MaYTTR-04-05 screened out in this study shows high pathogenicity to C. huangbki larvae, and has a good application value in the control of this insect pest.

Key words: Cladiucha huangbki; Metarhizium anisopliae, bioassay, mortality; Manglietia yuyuanensis