Sunday, March 29, 2009

Biological Control of Two-spotted mite





In this activity we observed the release of a predatory mite to control a two-spotted mite infestation on Jatropha macrantha, a tropical plant, located in the Botanical Gardens succulent house. 

Mites are part of the class Arachnida, having 4 pairs of legs (although nymphs have 3 pairs). Both adults and nymphs have piercing and sucking mouthparts and feed on a variety of plants. 
These pests are located on the underside of leaves and can be just visible to the naked eye. They produce quantities of fine webbing. 

Damage to the leaves can manifest as blisters, curls, chlorosis, defoliation, abnormal pigmentation, or as in this case silvering of the leaves. Fruit can be malformed. In cold temperatures, males die but the adult females can overwinter on lower parts of main stem, in cracks or damaged bark and under debris round the base of the main stem. The hibernating adult females change colour from pale greenish or yellowish to red. Populations are greatly reduced in long periods of rain or with good irrigation. Conditions favoured are high temperatues, particularly in summer months. 

The two predatory mites available in Australia are Typhlodromus occidentalis  and Phytoseiulus persimilis, the latter being the one available through private companies. 

Reference : Kerruish, A-194

1 comment:

  1. Great!!!

    Warmer temperatures are required for both types of predatory mite, colder conditions in Tasmania negate the effectiveness of these treatments in outside locations. Best in greenhouse treatments.

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