Virulence and pre-lethal reproductive effects of Metarhizium anisopliae var. anisopliae on Pseudococcus viburni (Hemiptera: Pseudococcidae)

Aldo Pereira1*, Pedro Casals1, Ana María Salazar2, and Marcos Gerding2

Obscure mealybug, Pseudococcus viburni (Signoret), is a cosmopolitan pest that causes damage by suction of vascular juices and the production of honeydew, as well as for being a quarantine insect. Within control options, entomopathogenic fungi are a good alternative, nevertheless, more research is needed. In this research, the Metarhizium anisopliae var. anisopliae (Metschnikoff) isolate Qu-M984 was evaluated on P. viburni under laboratory conditions. Virulence was evaluated by lethal dose 50 (LD50) and lethal time 50 (LT50), for each of the four life stages of the female. The doses tested were 105, 106, 107 and 108 conidia mL-1. Also fecundity, egg size, fertility, and longevity of adult females were evaluated at doses of 105 and 106 conidia mL-1, the evaluations were made every 2 d throughout the insect life time. The LD50 and LT50 obtained were variable for each life stage, although without statistical differences among life stages (P > 0.05), ranging from LD50 = 7.3 × 105 to 4.9 × 109 conidia mL-1 and LT50 = 7.74 to 9.97 d at 108 conidia mL-1. Significant differences (P ≤ 0.05) were observed on longevity at 106 conidia mL-1. Longevity was 29% less compared to the control. This result on longevity at relatively low dose is relevant due to the fact that decrease possibilities to find live quarantine insects at the moment of harvest. Fertility, fecundity and egg size showed no differences (P > 0.05).

Keywords: lethal dose, lethal time, biological control, entomopathogenic fungus, fecundity, fertility, longevity.
1Universidad de Concepción, Facultad de Agronomía, Casilla 537, Chillán, Chile. *Corresponding author (apereirav@udec.cl).
2Instituto de Investigaciones Agropecuarias INIA, Casilla 426, Chillán, Chile.