Host range testing methods
Parameters that can be measured
This section is designed to provide ideas of the range of parameters that might be
included within an EPA application to summarise the results of host range
In reality an in depth discussion of each parameter is not possible here, as the biology
of each target and agent organism will need to dictate the appropriate methods used.
Oviposition – number of eggs laid
Qualitative severity of damage from adult feeding
Percentage adult survival when fed only that species
Larval development rate fed only that species
Larval final body size/ pupal weight fed only that species
Sex ratio resulting from larval feeding on only that species
Percentage larval survival to pupa or adult fed only that species
Oogenesis after larva fed only that species
Multi-generation population persistence fed only that species
Latency to oviposit or initiate feeding
Proportion of population accepting species for oviposition
Proportion of population accepting species for feeding
Proportion of population located on that plant over time
Comparative levels of plant damage
The most useful parameters to be measured in any host range test of a weed biocontrol
agent is necessarily going to be dictated by the biology and behaviour of the agent.
Many of the research papers referred to in this website can assist with designing the
most appropriate test and therefore the parameters to be measured. We therefore urge applicants
to be familiar with the relevant literature and utilise any specific methods that have been
shown to be relevant to biology and behaviour of their proposed biocontrol agent.
There are almost infinite numbers of parameters that could be measured in host range tests.
With parasitoids and predators some common ones are included in the above list. A subset
of these are discussed in detail in van Driesche and Murray (2004). The applicant is encouraged to
consult this resource as well as being familiar with any behavioural or ecological
research on the target or closely related insects. Behavioural research papers can provide
invaluable information on the host searching and oviposition or feeding behaviour
of the agent. The most appropriate parameters to record can then be identified for each of
the host range tests undertaken.
- Number of prey eaten per predator per unit of time
- Predator survival (days) when predator is fed only a given prey
- Egg development (oogenesis) by adult predators fed a given prey
- Ability of prey to elicit predator oviposition
- Number of eggs laid
- Larval survival and rate of development
- Survival or mortality of test species
- Weight and fecundity of adults reared from test species
- Successful upwind flight to a herbivore/ plant complex
- Parasitoid responsiveness to a test species' kairomones
- Parasitism rate
- Rate of encapsulation by the host
- Emergence success and size of parasitoid progeny
- Sex ratio and fecundity of parasitoid progeny
- Latency to attack
- Attack rate
van Driesche R.G. and Murray T.J. (2004).
Parameters used in laboratory host range tests.
Pp. 56-67 In: Assessing host ranges for parasitoids and predators used for classical biological control: a guide to best practice, R.G. Van Driesche and R. Reardon (Ed.) USDA Forest Service, Morgantown, West Virginia.