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Pseudococcus viburni (Hemiptera: Pseudococcidae), the obscure mealybug, is a serious polyphagous, cosmopolitan agricultural insect pest that affects deciduous fruit production in South Africa. The presence of the mealybug in orchards results in significant damage to crops, with economic implications. The potential use of two entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN), as biological control agents against P. viburni, was assessed under laboratory conditions, using screening bioassays. The EPF isolates, Metarhizium robertsii (6EIKEN) and M. pinghaense (5HEID), tested at a conidial concentration of 1 × 107 conidia/ml, proved to be effective against the adult stage female mealybugs, causing 96% ± 6% and 91% ± 13% mortality, respectively, 7 days post inoculation, when incubated at 25°C with humidity levels of > 95%. Heterorhabditis indica, applied at a concentration of 200 infective juveniles per insect, was found to be the most effective EPN against P. viburni, causing 79% mortality, 48 h post inoculation, while incubated at 25°C. Further bioassays showed a positive correlation between insect mortality and conidial concentration as well as exposure time. The study represents the first report on the pathogenicity of multiple local and commercial EPF isolates to control P. viburni and several local EPN isolates against P. viburni. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi (EPF) are important soil-dwelling entomopathogens, which can be used as biological control agents against pest insects. EPF are capable of causing lethal epizootics in pest insect populations in agroecosystems. During a survey of the orchard soil at an organic farm, different EPF species were collected and identified to species level, using both morphological and molecular techniques. The EPF were trapped from soil samples taken from an apricot orchard. The traps, which were baited in the laboratory, used susceptible host insects, including the last-instar larvae of Galleria mellonella (wax moth larvae) and Tenebrio molitor (mealworm larvae). The potential pathogenicity of the local Metarhizium majus isolate was tested and verified using susceptible laboratory-reared last-instar T. molitor larvae. The identification of the M. majus isolated from South African soil was verified using both morphological and molecular techniques. The occurrence of M. majus in the South African soil environment had not previously been reported. [ABSTRACT FROM AUTHOR]