Control of the mealybug, Pseudococcus viburni, using entomopathogenic fungi in deciduous fruit orchards

Pseudococcus viburni, a serious polyphagous agricultural insect pest affecting deciduous fruit production in South Africa. The mealybug result in significant damages to crops in orchards, with economic implications. The study objectives were to assess the potential of entomopathogenic fungi (EPF) and nematodes (EPNs), as biological control agents against P. viburni.

Screening bioassays testing the pathogenicity of local EPF and EPNs against P. viburni, were conducted. The best EPF and EPN isolates were selected and the effect of their combination when

used against the mealybug was tested. A protocol for conidia mass culture of the two best EPF isolates was developed.

Two EPF, Metarhizium pinghaense and M. robertsii, and one EPN, Heterorhabditis indica, were identified as the most effective entomopathogens against P. viburni. Interaction between the entomopathogens, when used in combination, was found to have an additive effect. Conidia of the EPF isolates can be mass cultured using rice and blastospores.

The study has showed that both local EPF and EPNs can be employed to alleviate the problem of P. viburni infestation in the deciduous fruit production areas. The isolates can also be successfully mass produced, formulated and made available to fruit growers for field application against the mealybug.

The local EPF, M. pinghaense and M. robertsii, and EPN, H. indica, have proven to be effective biocontrol agents of the obscure mealybug and can be mass produced using rice grains.