There are quite a few methods of encouraging insect predators and here are just a few for you to engage in . . .
Create a suitable habitat for insect predators
Flowering shrubs and trees throughout the garden will attract many beneficial insects including parasitic wasps which require pollen and nectar for their growth and maturity.
Plants belonging to Umbelliferae family are particularly effective in attracting natural enemies of pests.
Provide alternate hosts for pests
To ensure availability of food for the beneficial organisms, grow alternate host plants along fence lines and in between cultivated crops. The natural enemy populations on these alternate host plants will control pests attacking the cultivated crop.
Provide nesting sites for frogs, reptiles and birds
Logs of dead trees, irregularly shaped rocks with crevices and cavities and plenty of mulch can be a good nesting sites for snakes, lizards, frogs, rove beetles and carabid beetles and carabid beetles, which feed on insects.
Increase humidity by providing water holes
Humidity is much needed for the survival of natural enemies. It serves as a source of drinking water for reptiles, birds and frogs. Many predatory insects live in, on and near water. Well-vegetated small dams, little water pools and swales scattered throughout the garden will create conditions for the build-up of natural enemies.
In regards to fungal pathogens,the practice of mixed cropping is desirable as the root emits of another crop can be toxic to the pathogen. Mixed cropping also encourages soil microbes which, in turn, act as barriers to the fungal pathogen.
Continuously Reduce dust build up in crop plants
Dust inhibits the functioning of natural enemies. Growing well-designed windbreaks and ground cover crops like centrosema and lablab bean will reduce dust. Use of overhead sprinklers will also help periodically
in washing off the dust.
Avoid using chemical pesticides
Chemical pesticides eliminate beneficial insects. Improved application method should be developed and minimum doses should be applied.