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Wednesday, May 23, 2012

The Lab Has Spoken…

WSU sampleI recently received an email from Erin O’Rourke of WSU’s Bee Diagnostic Lab, sharing the Lab’s findings of the sample of bees from my spring dwindling colony (see “Necropsy Pending,” 4/27/2012). Over the period of a half dozen days in March I collected dead bees from a catcher board placed at the entrance of the distressed hive, bottled them up, sent them off to the Bee Lab, and anxiously awaited their findings. The report was surprising, yet puzzling:

Nosema spores: 0 spores per bee (Good, but a surprise)

Tracheal mites: 0 % colony infection (Good news indeed)

Varroa mites: 1.6 mites per 100 bees (Seemed excessive…)

Here I quote from Ms. O’Rourke’s email: “Unfortunately, the data from this sample did not yield any definitive explanation for why the colonies are suffering such losses.” O’Rourke continued: “Varroa mites are present but at a relatively low level.” One and a half mites per 100 bees seems like a hefty amount of parasites…but Ms. O’Rourke and colleagues are the experts, not me. A strong colony can have between forty and sixty thousand bees at peak population; however, if a hive has a severe mite infestation, it’s not likely to achieve such numbers—if it survives at all. The Bee Lab and I did concur on one point. Ms. O’Rourke: “Your assessment of the seasonal presence of nosema symptoms in the spring that subside with the availability of fresh forage corresponds to our research. There was pollen in your sample.” I was aware that two or three deceased bees in my sample carried pollen pellets. That bees bearing fresh pollen should die before delivering the goods seemed to me an indicator that something was amiss.

I thought it only right, for the purposes of bee diagnostics and research, to respond to the Bee Lab’s findings…to thank them, of course, for the fine work they do for us beekeepers, but also to give Ms. O’Rourke an update on the hive sampled. In my letter to the Lab I gave a detailed history of my experiences keeping bees here in the Valley; however, I purposely withheld certain information about the distressed colony because it didn’t seem pertinent to my sample. I had examined the colony shortly before my sampling and straight off noticed a problem. In addition to the adult bees present, the hive had three frames of capped brood—bees in their pupa stage--shortly to emerge as adults. I would have wished for four of five frames in mid-March, but only three frames of brood did not spell disaster for the colony. I searched for new eggs on an outer frame of capped brood.

Examining the egg laying pattern of the colony’s queen is an excellent way to assess the health of the colony. A honeybee egg is translucent, shaped like a tiny bean. The queen lays one egg in the center of the cell and glues it on end so it stands upright like a tiny appendix. By tilting the frame to the light, the beekeeper can easily spot the eggs and thus check the queen’s egg pattern. The queen begins laying eggs in the center of the comb and lays outwards until most of brood comb is full of eggs. A sporadic egg pattern, eggs laid helter skelter, indicates a failing queen. The outer cells of the brood comb are left to store the nectar required to feed the larvae. Because the eggs laid in the center of the comb metamorphose first, the beekeeper knows to look for freshly laid eggs at the perimeter of the capped (pupa stage) brood on each frame. Years of beekeeping have taught me to look first for eggs and examine their pattern to assess the health of the hive and the vitality of the queen; eggs, larvae, and capped brood are the colony’s indicator of wellness.

That was why I was alarmed at what I discovered on a brood comb. I located eggs where I expected them but noticed straight off many cells contained multiple eggs, two and three per cell. In this case, strange as it seems, less is better than more. Multiple eggs per cell indicate something is amiss with the queen and the hive is no longer “queen-rite.” She has either failed or died and her attendants haven’t been able to replace her. In desperation, some workers try to rescue the colony by assuming the queen’s egg laying role and becoming “laying workers” themselves. And even though the worker bees are females, too, theirs is a futile attempt. The queen is the only fertile female and can lay at will both fertilized and infertile eggs: the former become workers; the latter drones. The eggs from laying workers metamorphose into males, drones, and once a colony is “governed” by laying workers, it most certainly is doomed to extinction (not meant as“male-bashing,” just a simple fact). Attempts to requeen the colony will fail because the laying workers will usurp any newcomer and sting her to death, further sealing the hive’s fate. Egg-laying workers lack the genetic code that signals them to lay one egg per cell and will lay multiple eggs. These are readily visible on the floor of the cell like little stacks of cordwood or a jumble of pick-up sticks.

The workers bees are acutely in tune with their leader’s health and in most cases will “supersede”(replace) her when they sense she is ailing, injured or suddenly dies. This period of interregnum is a perilous time in the life of a honeybee colony. Any fertilized egg has the potential to become a queen bee; however, there is a very narrow window of time for the workers to select the queen’s replacement. Larvae selected to replace their faltering mother should be 2 to 3 days old (to insure they are fed the maximum amount of “royal jelly,” a special ambrosia fit for a queen). If, for whatever reason, this narrow margin is missed, the colony will “drone” itself into oblivion. Larvae much older will not produce a perfect queen, either. Once the old queen is superseded, a new virgin queen will emerge as early as eleven days later. By the time she takes her mating flight and begins her egg laying duties, ten more days may have passed. (In the spring our fickle Valley weather makes a queen’s mating flight even more problematic.) And a full month may go by before any new eggs are laid. With a "gestation period” of twenty-one days from egg to adult worker bee, such an interruption in the brood cycle can have a significant impact on the strength of the honeybee colony.

My response to the superfluous eggs? “Oh, great…first disease and mites, now laying workers!”and wrote the hive off as a certain “deadout.” I didn’t trouble Ms. O’Rourke with this information because the hive was distressed before I discovered the laying worker scenario and for all I knew, its dwindling and queenless condition was cause and effect.

What I did share with Erin in a follow-up email was the surprise I found a week later when I looked in the problem hive and discovered a lovely egg pattern, and what’s more, a nice, plump, healthy-looking queen! I mulled over this new development and somewhere in my beekeeping repertoire of information, I remember reading that sometimes a new queen, healthy and vigorous, being new to her role, will sometimes enthusiastically lay more than one egg per cell. In retrospect I remembered that the excess eggs were not spread willy nilly  but were deposited in the cell on end, each correctly positioned, just as a single egg should be.

In talking with beekeeping newbies, long time beekeepers, or the purely curious about the satisfying pastime of keeping bees, I usually include this statement: “I’ve been keeping bees since I was fourteen years old, and every season I learn something new or experience some oddity I’ve never encountered before.” Perhaps that’s why I keep on keeping bees: you continue on, wondering just what’s going to happen next. And thanks to Erin and WSU’s Bee Diagnostic Lab, I feel I’m not alone in this mysterious and challenging era of modern beekeeping.

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