Containment testing

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 testing. 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.

Weed biocontrol

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.

Insect biocontrol (van Driesche and Murray 2004)

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

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.

References

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.