What is a varroa mite and what is its connection to California agriculture?

Answer 1

Varroa mites are part of the Arachnid family, which also includes Spiders. The adult is chocolate brown, shiny and the size of a pin head and only the mature female travels. They travel by hitching a ride on a bee from an infected hive, can drop off in a flower and await their next flight, where they'll attach to the next bee to arrive. Then they are carried to the next colony, where they may live on a bee for a while, then drop off and find the brood nest and get into a larval cell.
Varroa can only reproduce on honey bee brood, laying eggs after the brood cell is sealed to pupate. Here, the female Varroa mite lays her 5-8 eggs eggs. The first egg to hatch is usually male, the rest female. After the 2 maturation phases have passed and they become mature, these mate in the cell the females leave to continue the cycle. Any immature females and the male will die in the cell.
While in the larval cell, the mother mite will feed on the bee larvae, as will the immature and developing mites, inhibiting the growth and often killing it. If it does survive, the newly hatched bee will usually have stunted wings, rendering it unable to fly, and it is rejected by the colony to die.
Outside the cell, the mite will attach to a honeybee, often snuggling up under the plates of the abdomen, feeding on the body fluids, in much the same manner as a tick on a dog, only on a much bigger scale. This weakens the bee and it will soon die.
The effect of these mites on the honeybee populations (worldwide, not just in California) has been enormous, and continues, as Varroa spreads across the globe, collapsing colonies on a large scale. Wild bee populations as well as many domestic hives were decimated before we realised the Varroa was there, so vigilance by bee-keepers is now vital to control the mite. This, unfortunately, means the bee populations are reliant on human intervention, as the Varroa mite spreads and with it, introduces various viruses to the weakened colony.
Pollination of crops and fruit trees is severely reduced in the wake of honey bee population reduction, translating to major harvest shortfalls. It's estimated that up to 80% of foodcrop pollination is manged by bees, so on this scale, the Varroa is an invader of serious proportion. Funds need to be put into the management of it so the foodcrop industry can be sustained.