Hymenoptera
Definition
The Hymenoptera is a large order of organisms within the phylum Arthropoda, which contains insects like, bees, wasps, sawflies, and ants. The name is derived from the greek words "Hymen" or "membrane" and "Ptera" or "wings", which is perfectly describing the fact that their wings are connected into one point called the "Hamuli", and the membraneous tissue it is formed. Like most insects, these appeared at an early stage of earth's history, which according to a study done by D.A. Grimaldi, M.S. Engel et al, have been around since 281 million years ago (Triassic Period). The Hymenopteran who have evolved into a societal way of living(Cretaceous Period), similar to pre-historical humans, created a very well adapted form of resilience for the succession of its offspring. However, many different species still live solitarily, requiring others only for mating. The organisms, who have a social life, live in a nest (ants) or a hive (bees, wasps), which are all descendants of one queen. When the hive or nest is established by a queen in early spring, it begins producing its offspring that will work in their pre-assigned roles, depending on their gender.
Anatomy
The anatomy of hymenopterans are very similar to other insects. The ones who fly, usually have two pairs of wings. Their mouths can have two forms, just mandibles used for chewing, or with the addition of the proboscis used for drinking liquids, such as nectar. They have two larger compound eyes, used to differentiate brightness and color, and also three smaller eyes called "ocelli" that are much simpler. Flying insects have their hind wings with hooked bristles called "hamuli" that holds both the fore wings and hind wings together. The number of hamuli vary between species and their sizes, with wasps having more than the usual two to three hamuli present in smaller species. Like most insects, their bodies are divided into three sections, head, thorax and abdomen.
The hymenoptera have an ovipositor, that in older species evolved into a blade-like structure used for slicing plant tissues. However, many today use them for piercing. In some species, we see today an ovipositor that evolved into a stinger in which the tip is used to inject venom and their eggs are laid from the base of the structure. The stinger is usually used to immobilize prey, that could be used to insert their eggs inside, but we see many bees and wasps using for self defense.
The larvae of the hymenoptera have a head region, three thoracic segments, and nine or ten abdominal segments. The hymenoptera, is further divided into the Symphyta and Apocrita. The former includes sawflies, whose larvae feed on leaves, have large mandibles for chewing; six thoracic limbs, and six to eight abdominal prolegs. However, their prolegs do not have spines, and their antennae are reduced to just stubs. Furthermore, the larvae that lives on wood or stem borers have no abdominal prolegs and the thoracic legs are smaller than the non-borers.
In the Apocrita, whose species are wasps and bees, however, cannot live freely. The lack of legs, and their shape resembling a maggot, requires them to be taken care either by the solitary wasp who laid them, or by the workers and queen in a beehive. If the larvae was laid by a wasp, it will most likely be living inside of the immobilized insect it captured, where the offspring can feed off of the prey. The larvae laid in the insect have some morphological differences, the head is reduced into the prothorax, the compound eyes are poorly developed, with no ocelli; very small or absent antennae and toothlike mandibles. It also lacks the ability to defecate, since their digestive system is not completed, to avoid contamination in the environment they live. The larvae that has a stinger, generally has ten spiracles, for breathing, while the parasitic form usually has nine.
PHOTOS
Reproduction
In the order Hymenoptera, reproduction uses the Haplodiploid sex-determination system, in which the number of chromosomes determines their gender. If the eggs are fertilized by both parent's gametes, the individual is diploid and develops into a female.
However, if the egg is not fertilized by two sets of gametes, the zygote is haploid, and develops into a male. The important factor in this system is that the female is under total control of which gender her offspring will be, depending on what the nest or hive needs in the moment.
Although this system seems very simple to understand, it actually is much more complex than only the number os chromosomes present. In many hymenopterans, the gender is determined in a single gene locus with many alleles. In these organisms, males are haploid and females are diploid heterozygous at the sex locus. However, a diploid organism could be homozygous which develops into a male. This is more likely to happen when we have parents who were siblings reproducing. Diploid males are known for being produced by inbreeding, in many ant, bee, and wasp species. These males organisms, usually are infertile but you can find some species with fertile diploid males.
A problem that appears due to this reproduction system is that females on average have more genes in common with their sisters than with their daughters. Therefore, cooperation among kindred females may be unusually advantageous, which contributed to the multiple origins of eusociality within this order. In many colonies, we see the removal of eggs laid by other workers due to the increase in relatedness to direct siblings, a behavior called worker policing.