Living With Degree Days

blow flies

Left: Blowflies reared for 5 days at the constant temperature indicated

Right: Typical Development Vs Temperature curve

Insects do not maintain a constant temperature.  Insect body temperature varies with ambient temperature.  Insect rate of growth and development is proportional to temperature. Below a minimum temperature, there is no development. Above the minimum temperature (Developmental Threshold), the growth rate increases to a maximum, then declines as insects suffer heat stress near the maximum tolerated temperature.

Each insect species has its own developmental threshold and development vs temperature curve.  These parameters must be measured empirically and are known for most economically important insects.  Knowing these parameters enables insect biologists to create models that predict when insects will be present based on temperature data alone. Good models can focus scouting and pest management measures to only those times when it would be possible for an insect stage of interest to be present.  Combined with weather forecasts, the emergence of some pest species can be predicted in advance with the same certainty as the weather forecast.

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in by jjneal, Environment, Pest Management. Bookmark the permalink.

1 Response to Living With Degree Days

  1. Pingback: Living With Degree Days – Entomo Planet

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s