Biology and Control of Brevipalpus australis.
AbstractA mite identified as Brevipalpus australis[Brevipalpus californicus] (Tucker), which is polyphagous and widely distributed throughout the world, was observed feeding on orchids of several species at College Park, Maryland, in 1946 and has since become a potentially serious pest of orchids in other parts of the United States. The mites occurred mostly on the lower surfaces of the leaves and caused the appearance of silvery and sunken areas.
In rearing experiments, the egg, larval, protonymphal, deutonymphal and adult stages average 9.1, 6, 4.1, 7 and 25 days, respectively. Eaising the temperature reduced the duration of the egg stage, and raising the relative humidity increased the percentage hatch. Parthenogenesis was observed and probably occurs in a large proportion of the females, as males were very rare. The adults were the most active. The preoviposition period averaged 3.8 days, and eggs were laid singly and at random on the leaves, usually on the lower surfaces. Sprays of proprietary mixtures of pyrethrum and rotenone and of ethyl phosphates gave some control, but had less immediate or residual effect than Dimite (l, l-bis(p-chlorophenyl)ethanol), which gave high initial mortality when applied to infested Dendrobium plants; no living mites could be found a week after treatment. This material was later successfully used for large-scale greenhouse treatments and caused no damage to orchids of several genera.