Development of brood infected with American foulbrood
The developmental stages of worker brood infected with AFB are outlined in Fig. 7 below.
Larvae are most susceptible to AFB infection when they are less than 24 hours old. Millions of spores are required to infect a larva more than two days old, but larvae up to 24 hours old can become infected with ten spores or fewer.
Although the AFB vegetative rods multiply in the gut of the larva, they do not penetrate the gut wall and multiply in its tissues until it stretches out before pupation (prepupal stage). Visual disease symptoms do not become apparent until death occurs, either just before or just after the larva pupates.
Infected larvae do not usually exhibit disease symptoms until after the cells have been capped. Where uncapped diseased larvae and pupae are found it is usually because the cappings have been removed by house bees.
How well do you know what you need to know about AFB and beekeeping? Take our short quiz and find out.
Our videos cover everything from your legal obligations to how to recognise AFB, collecting cell and bee samples and more.
There’s a lot of good information here, telling you everything you need to know about recognising AFB: the visual symptoms, smell of AFB and more.
New Zealand beekeepers have a number of legal obligations that must be met regarding AFB disease. Read the shortened list in summary, here.
Most hives become infected because bees, honey or equipment have been put into a hive from another hive that is infected with AFB. Lower your chances of an AFB infection by reading this section.
Find out when the next AFB Recognition and Competency Courses, or Refresher Courses are available. These are held throughout the year in various New Zealand locations across the South Island and North Island.