A Mealworm’s Journey

I have taken care of mealworms for a while now, and for those who do not know what mealworms are, they are feeder insects for reptiles, some fish, and a good protein source for other insects. Overall, they are easy to take care of, requiring very little moisture that can be provided for with root vegetables like carrots or potatoes. The substrate in which to keep them can be as simple as pouring about an inch of oats for them to eat and dig into.

This is convenient for mealworms, as they spend a majority of their larval stage much like any other larva, which is just eating. Depending on what size you get them, they may pupate within a few months or next year, mainly due to needing to shed their skin multiple times before they reach an appropriate size. When they’ve reached an appropriate size, they begin to pupate and their previously short legs that almost all larval stages possess begin to develop into the spiny legs that beetles have.

After a period of time, they emerge as a rather large mealworm beetle, about an inch in length for my own beetles. These beetles will then mate with each other, assuming they are male and female, and the cycle repeats, much like other insects. However, it isn’t as simple as just placing them in a large tub, filling it with oats, and adding vegetables every so often. In fact, it gets even more complicated, as the mealworm, as both larval and beetle stages, will eat almost anything, including their own eggs, pupa, and smaller mealworms. Which means that you need a separate container for all stages of life: larval, pupa, and beetle.

Heir to the Throne

Despite queen bees having a much longer lifespan than workers, they still die from age eventually. But there are circumstances where the queen dies even earlier than anticipated. This can be detrimental to the profits of beekeepers, who require healthy, thriving colonies in order to reach a quota of honey. Fortunately, there are ways to fix this problem: requeening the hive or simply waiting for the bees to produce another queen bee.

Requeening can be quite random, as the beekeeper must observe how the workers will respond to the new queen. The queen is placed in a requeening cage and left in the hive. At first, they will begin swarming her, attempting to harm it, as they are not familiar with the new pheromones produced by the queen. Over time, they will begin to accept her, and after they have subsided, the queen can be released from the cage and will begin her duties as a queen. However. the workers may not accept her and may continue to harm her. In these circumstances, the queen must be removed and a new one will need to be used.

Waiting for the new queen is a more natural method, but requires more time, usually employed by wild bee colonies. When the queen bee is dead, the workers will automatically begin making a queen chamber in which new queen larvae can be raised. These larvae are fed copious amounts of royal jelly, a special food produced by the workers, up to the point where they are swimming in it. These larvae will eventually emerge as virgin queen bees and will fight each other in order to become the only remaining queen before leaving the hive, mating with drones from other colonies, and returning.

Queen Mandibular Pheromone: Foraging Genes

Of course, some workers are needed to go find food for the colony, mainly in the form of nectar and pollen. These workers aren’t just selected at random, but are the older bees of the colony that have gone numb to the effects of QMP. Their receptors have been over-stimulated and, thus, require higher doses in order to feel their effects. In fact, they begin to express a dislike for QMP, sometimes avoiding it whenever possible. However, since the concentration of QMP won’t increase, the expression of “foraging genes” begins.

This can be summed up in the expression of the Amfor gene, which codes for 3′, 5′-cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG). Other genes include genes related to phototransduction processes and antibacterial peptide biosynthetic processes.

The mushroom bodies, as mentioned in the previous post, are responsible for olfactory and mechanosensory inputs, as well as gustatory inputs and higher-order thinking. As the bee becomes less responsive to QMP, their brains begin to change and all of their original functions are enhanced. The higher-order thinking is only possible through the development of the mushroom bodies and provides the bee with mental capabilities like memory and problem solving.

The increase of JH in the body of workers is linked to the decrease of Vg in their bodies. And because of this decrease in Vg, the number of hemocytes in the hemolymph also decreases, making them more susceptible to disease. However, because of the expression of antibacterial peptide biosynthetic processes, forager bees gain a sort of immune system, where they actually undergo fever-like symptoms that humans go through when sick.

Queen Mandibular Pheromone: Nursing Genes

In a presentation for my Genomics & Proteomics class, my classmate and I presented on Queen Mandibular Pheromone (QMP). It is the single most important pheromone in the colony and has profound effects on both the gene expression and physiological aspects of a colony’s workers.

The main function of QMP is to enhance the expression of “nursing genes”. Nursing genes result in the production of what is known as vitellogenin (Vg).

Vg is responsible for producing hemocytes, which are immune cells in their blood, regulating reproductive abilities of workers, and increases longevity by having antioxidant effects. In addition, it causes worker bees to remain the hive while also restraining their mental capabilities (which will be discussed in the next post).

Hemocytes are responsible for eliminating threats in the hemolymph of insects and does its job effectively. However, as the workers get older, their responsiveness to QMP diminishes: Vg is less prevalent in their bodies and is replaced by juvenile hormone (JH), hemocyte production is replaced by antibacterial peptide biosynthetic processes, and the mushroom bodies of their brains begins to develop.

The First Nanitic

Worker ants are the backbone of an ant colony. Without them, the larvae are not able to be fed, unless the queen risks her own survival to find sustenance. Just today, the first worker, known as a nanitic, eclosed from one of the pupa.

Ants eclose as a pale white, due to being covered for so long. However, after staying sheltered in the nest, they begin to develop their dark, familiar colors. Unfortunately, I was not able to witness the nanitic eclose but, hopefully, I will get to see one or two eclosing workers in the years to come.