By: Pablo Montesinos Arraiz
Figure 1. Bee nest
At a base level, the zootechnical management and the general management of hives depend intrinsically on the development and growth of the brood nest. The brood nest has to do with the quantity, concentration, distribution and location of the eggs, the open brood and the sealed brood that are mainly in the central combs of the bee nest. The lateral and upper combs will be occupied by reserves of pollen and nectar or honey (Figure 1). The brood nest also may extend into the lateral and upper combs of the bee nest, if there is not sufficient space for the queen to lay eggs and/or the amount of pollen and nectar collected by the bees is increasing.
The patterns of the brood nest refer to the presence and/or absence of the elements that constitute the brood nest: the eggs, the open brood and the sealed brood of the workers (Figure 2). Drones are reared in significant numbers only during breeding times of the colony. During the Spring, Summer, Autumn and part of the Winter, the colonies have the pattern X, X, X in the brood nest. The first X indicates the presence of eggs of one, two and three days, the second X of open brood (larvae in the different stages before being sealed); and the third X of sealed brood (larvae that have passed to the pupal stage). This pattern (X, X, X) in quantitative terms, increases from Summer to Autumn, until it reaches its maximum level, in relation to the abundance of nectar and pollen and the physical space that the colony occupies in the hive:
Normal Pattern of the Brood Nest
X, X, X
Figure 2. Brood nest
In temperate regions, at the end of Autumn, the eggs, the open brood, the sealed brood and the bee population begin to decrease because the queen is laying fewer and fewer eggs. The bee population is grouping around the queen to form the Winter cluster. The bees bring less and less nectar and pollen to the hive. The queen, in Winter, stops egg laying completely, and so, there will not be open brood and sealed brood either. The following sequential changes in the pattern of the brood nest have been observed:
O, X, X ↓
O, O, X ↓
O, O, O ↕
The normal pattern of the brood nest, X, X, X resumes as Winter gives way to Spring. This occurs gradually:
X, O, O ↓
X, X, O ↓
X, X, X ↕
It has become present again, the cycle of quantitative development and growth of the brood nest and bee population. Honey and pollen will also progressively increase in the hive.
However, the queen can die unexpectedly and suddenly, due to a serious injury caused by the beekeeper at the time of inspecting the hive, by a predator or by any disease. The death of the queen will bring with it, while the process of emergency queen rearing is carried out, changes in the sequence of the normal pattern of the brood nest.
The queen that has died is called the “old queen” because she is the one that the colony had in the last inspection of the hive; and the “new queen”, comes from the emergency queen rearing. Once the new queen has reached sexual maturity and has mated, she will start laying eggs, with the consequent modifications in the patterns of the brood nest. Alterations in the patterns of the brood nest, triggered by queen rearing processes, swarming, supersedure; or queen replacement by the beekeeper are not considered here.
Sequential Changes in the Normal Pattern of the Brood Nest, From the Moment the Old Queen Dies
O, X, X ↓
O2, X, X ↓
O3, X, X ↓
O, O, X ↓
O, O, O ↕
The pattern represented by O, X, X, indicates a total absence of eggs. The queen has died three days before. If there are two- and three-day-old eggs, O2; it means that the queen has not been dead for more than 24 hours. The presence of only three-day-old eggs, O3; indicates the death of the queen 48 hours ago. For the first X, correspond those eggs that have already completed the incubation period (three days) and have become larvae (open brood). If one-day-old larvae are found; it means that the queen died four days ago; two-day-old larvae, five days ago; three-day-old larvae; six days ago; four-day-old larvae; seven days ago; and with five-day-old larvae; the queen died eight days ago. The larvae that have completed their development and have been sealed (sealed brood), are represented by the second X.
The pattern O, O, X indicates the absence of eggs of one, two and three days, and also the absence of larvae (open brood), and more than eight days have elapsed and all larvae have been capped; the X represents the sealed brood.
O, O, O is the pattern observed from the third week after the queen death. Besides no eggs and larvae, there is not sealed brood because all pupae have transformed into adult bees and have emerged from their cells. This pattern of the brood nest could continue if the colony is unsuccessful in raising a new queen.
When the old queen dies while the colony is in normal conditions, that is, it has open brood with larvae one to two days old, sealed brood, young bees (nurses) and honey and pollen reserves, the workers begin to rear a new queen in the first five to six hours (as is assumed here) after the death of the queen or from 12 to 48 hours later. To do this, the workers modify one or several worker cells that contain larvae less than two days old and feed them with abundant royal jelly, transforming them into queen cups and then into emergency queen cells, from which the new queen will be born and that will be established after having killed other queens that could have been born.
Sequential Changes in the Normal Pattern of the Brood Nest, From the Moment the New Queen Begins Egg Laying
Five days after birth, the queen reaches sexual maturity and leaves for her mating flights; generally mating on the first flight and laying eggs between the second and fourth day later. Here, it is assumed that the new queen starts egg laying three days after mating or eight days after being born, observing the pattern X1, O, O, which indicates the presence of eggs of one day, eggs of two days (X2, O, O) and eggs of three days (X3, O, O) and absence of open brood and of sealed brood. When the incubation period of the eggs ends (three days), and they become larvae, and are fed by the nurses (such feeding takes an average of 5.5 days); there will be in the brood nest the pattern X, X, O indicating eggs and open brood but absence of sealed brood. Eight days after the new queen has started egg laying, and since the open brood has been sealed, the brood nest will have again the pattern it had before the death of the old queen: X, X, X (eggs, open brood and sealed brood).
Abrupt Change of the Pattern of the Brood Nest
If in an orphaned hive, like the one described above, a fertilized queen is introduced; as long as more than eight but less than 21 days have elapsed in European bees (duration of the development stages of the workers) the sequence of the aforementioned patterns will be modified. It will then show the pattern X, O, X, which shows the presence of egg and sealed brood, but not open brood; since the egg laying comes from the new queen introduced by the beekeeper and the sealed brood from the old queen that was in the hive. Later, the pattern X, O, X will change to X, X, X. With that, the eggs, the open brood and the sealed brood will belong to the new queen introduced.
Circumstances Per Se of the Colony
The X, O, X pattern can also be found in those cases in which the queen, for whatever reason (organic or functional disorders, lack of sufficient nurses or lack of food reserves), has stopped laying eggs for eight days and the inspection of the hive is carried out just when the queen is re-establishing the egg laying and all the open brood has already been sealed.
