• Integrated Pest Management (IPM)

• Biological Control and IPM

• Components of IPM

• Benefits of using natural enemies

• Difficulties encountered with bio control

• Methods of releasing beneficials

• Getting Started with Biological Control

Integrated Pest Management (IPM) is a strategy which encourages the reduction of pesticide use by employing a variety of pest control options in combination to contain or manage pests below their economic injury levels. These options include:

• biological control

• cultural control

• varietal selection

• chemical control.

Adoption of IPM

For practical purposes, IPM programs can develop through three stages.

STAGE 1

• improved cultural and hygiene practices

• monitoring of pest to reduce pesticide use and achieve better timing of pesticide application

Some crops or situations may be unsuited to Stage 3, but will benefit from stage 1. Stage 3, the highest level of commitment, means investing time and money into encouraging biological agents. A decision to use broad spectrum pesticides in a Stage 3 IPM program cannot be taken lightly, as this may undo the work of the previous months or even years.

• as for stage 1, plus

• monitoring that also includes beneficial species

• selection of chemicals which are less hazardous to beneficials

• spot spraying and targeted spraying

• selective control of pests with the use of products such as pheromones, Nuclearpolyhedrosos virus, Bacillus thuringiensis, insect growth regulators and baits

STAGE 2

• as for stage 1 and 2, plus

• environmental modification to encourage beneficials

• release of mass-reared beneficials

STAGE 3

Biological Control and IPM

IPM systems consist of numerous elements with monitoring usually described as the "cornerstone of IPM". Biological controls, cultural practices, nutrition and irrigation management are important elements.

The degree to which biological control agents (BCA's) can be utilised will vary from crop to crop and from area to area and will depend on the answers to a series of questions. For example:

• Are there effective natural enemies for the major pests of this crop?
  Effective natural controls exist for some pests but not others.
  
• Are these mass reared for introduction or do they enter the crop from local populations?
  This will influence management practices. eg. conservation of refuge or alternative crops.
  
• What crops or types of vegetation are adjacent to the target crop?
  Some crops act as refuges for natural enemies while others can harbour unwanted pests.
  
• Is the crop being grown under "organic" or conventional classification?
  If the crop is "organic" some low level damage from pests may be more tolerable.
  
• Are there "soft" chemical options for use in conjunction with natural enemies?
  Soft options are available for some pests and not others.
  
• Is the crop life span and environment suitable for natural enemies?
  Short lived crops may not be suitable for BCA's.
  
• Are certain plant life stages suitable for natural enemies and others not?
  BCA's may be useful in early stages of a crop but not near harvest.
  

A crop consultant versed in biological control options will help you answer these questions so that an appropriate program will evolve. Each farm and crop has unique characteristics which need to be catered for in developing a program and responding to events as the season progresses.

In addition to these questions are those related to cost and practicality and the degree of difficulty controlling key pests with chemical means alone.

Benefits of utilising biological control agents

Numerous benefits arise from utilising natural enemies. Some are obvious while others are more hidden and difficult to quantify:

• BCA's assist in control of some important pests which have developed high levels of tolerance to chemical products - e.g. twospotted mites, Heliothis, cabbage moth.
  
• In combination with soft options, BCA's help to prolong the useful life of the remaining effective chemicals - less pests are subjected to the chemical and pests that escape the chemical have a good chance of being eaten by a BCA.
  
• Some BCA's are mass produced which can enable significant reductions in chemical use. These reductions also enable the movement of local beneficials into the crop. Some of these can be very significant in there own right.
  
• Natural enemies can enable control of pests in crops sensitive to chemicals.
  
• Reduce problems with withholding and re-entry periods.
  
• Minimise chemical residues in the end product and the environment generally.

Some difficulties with Biological Control

Some difficulties are usually encountered in the move to an IPM system. Practices and routines need to be modified and new information absorbed by the practitioners. The following are some areas that are likely to be important:

• Regular monitoring is necessary to identify pest outbreaks and their location within a crop. It may take time to develop suitable procedures and routines.
  
• "Soft" controls for some pests are available but not others. If unavailable, spot spraying with broad spectrum products may be more appropriate than widespread spraying.
  
• Some damage from pests may need to be tolerated. Some pests may be required to support a useful population of the natural enemy.
  
• Good timing is necessary when introducing natural enemies - not too early, not too late. For example: You may need to target moth flights, or detect early signs of a pest etc.
  
• Need to get natural enemies established quickly. If introducing mass reared BCA's, introduce appropriate numbers to facilitate quick establishment.
  
• Deciding when to or not to spray can be an issue. If soft options are available for the pest in question this is not such an issue.
  
• Providing a suitable environment. Very hot dry conditions are not conducive to some BCA's. Adjustments may need to made to favour BCA's, e.g. shade, windbreaks, overhead watering.
  
• Having an expectation that one cannot spray at all is incorrect and may result in failure of the IPM system. BCA's usually recover from occasional sprays of moderately toxic products and can remain at useful levels.

Methods of Introducing Bio Control Agents

BCA's can be used in various ways. These methods are usually divided up into the follow categories:

• Inoculative release: One or two releases early in pest infestation to control pest gradually. e.g. predatory mites in strawberries, Trichogramma in field crops, lacewing in field and greenhouse crops.
  
• Regular or dribble release method: Regular small release during likely problem periods, used like preventative fungicides. e.g. P. persimilis is nursery crops, Encarsia in green house crops.
  
• Inundative releases: Repeated high rate releases during periods of pressure for quick knock down. e.g. Cryptolaemus beetles, Trichogramma in green house crops, P. persimilis for dosing hot spots of TSM.
  
• Combination of above methods: e.g. initial high release rate for quick knock down followed by regular small releases.
  

Getting Started in Biological Control in Commercial Crops

• Seek specialist advice from suppliers of BCA's.
  
• Monitor crops regularly. Determine what level of pest you can tolerate.
  
• Determine which mass produced BCA's are suitable for your pests, crop and district.
  
• Identify any local BCA's that are likely to assist you.
  
• Determine the best times for introducing natural enemies.
  
• Replace broad spectrum sprays with biological or more selective insecticides if available.
  
• Ensure chemical residues have had time to disperse before introducing BCA's.
  
• Identify other practices which will assist establishment of BCA's. e.g. wind breaks.
  
• If appropriate, reorganise plantings and location of plantings to facilitate use of BCA's.
  
• Experiment with part of the crop or one planting.