Compatibility of Predatory Mite (Amblyseius californicus) with Entomopathogenic Fungi against Two Spotted Spider Mite (Tetranychus urticae. Koch)

Abstract

The two-spotted spider mite (Tetranchus urticae) is the most threatening pest of flower farms in Ethiopia. Biological control is becoming an acceptable practice to suppress the pest in greenhouse. Recently reported to control spider mite is a predatory mite native to Ethiopia. However, information on its ability to combine with other control measures is inadequate. This study was carried out to investigate its compatibility with two entomopathogenic fungi against T. urticae (Koch) under laboratory and glasshouse condition. Four fungal isolates: 9609, GG, MM and PPRC6 with four levels of conidial concentrations: 106, 107, 108 and 109conidia/ml were used as treatments. Amblyseius californicus motiles were recorded at four, six and eight days after application. Among conidial concentrations tested, MM x 107 and MM x 108 conidia/ml are showed no detrimental effect on A.californicus during all exposure time compared to others higher conidial concentrations during laboratory trial; thus they were combined with A.californicus to check their effect against T. urticae in greenhouse condition. Alive mite’s motiles were recorded for data analyses. Under greenhouse, during 6th and 8th days MM x 107 conidia/ml + 5:50 (A.californicus: T. urticae) ratio reduced numbers of T. urticae population by 44.37 and 43.33% respectively compared to untreated (0.01% Tween 80 solution alone) while population of T.urticae was reduced by 21.6 and 22.83% at A.californicas alone compared to untreated control. Therefore, from the present study the combination of MM x 107 conidia/ml + 5:50 (A.californicus: T. urticae) were found best for controlling spider mites populations under greenhouse conditions without adverse effect on A.californicus.