Caste: Termites
- PDF / 379,748 Bytes
- 8 Pages / 504.567 x 720 pts Page_size
- 89 Downloads / 215 Views
Caste: Termites Yves Roisin Evolutionary Biology & Ecology, Université Libre de Bruxelles, Brussels, Belgium
Caste Diversity in Termites Because termites are hemimetabolous insects, their basal developmental pathway goes through a series of active instars endowed with growing wing rudiments (called wing tips, buds, or pads), which ends in an imaginal molt at which wings fully develop. Traditionally in termites, wingless immature instars are called larvae, while those with wing rudiments are called nymphs (Fig. 1b). Termite castes derive from deviations from this straight egg-to-alate pathway. In contrast to hymenopteran polymorphism, which involves imagoes, termite polymorphism involves immatures. In a number of cases, termites may show temporal polymorphism, when members of a caste remain able to molt into another caste. The following castes can be distinguished in most termite societies [13, 14]. Imago. Winged adults (alates, Fig.1a) of both sexes are the disperser morphs. Both sexes are similar in appearance, although females often tend to be slightly larger and heavier than males. In females, the seventh sternite is enlarged, whereas the eighth and ninth are split and reduced to small lateral plates. Alates disperse during © Springer Nature Switzerland AG 2020 C. Starr (ed.), Encyclopedia of Social Insects, https://doi.org/10.1007/978-3-319-90306-4_141-1
massive nuptial flights, triggered by meteorological conditions and involving numerous colonies in the area at the same time. After the nuptial flight, the alates shed their wings and, as dealates, pair and undertake to ▶ found a new colony in which they become queen and king. Founders are primary reproductives. Colonies are usually founded by a single pair of dealates, but pleometrosis (foundation by several females) may occur. In some species, neighboring incipient colonies may fuse. Pleometrosis and colony fusion may result in colonies of mixed parentage, with a complex genetic composition. In many species, the colony founders can be replaced or supplemented by secondary reproductives, becoming functional within their colony of origin. Alates that shed their wings in their home colony to develop into secondary reproductives are called adultoids. In some species, adultoids can be pseudimagos – alates that do not achieve full sclerotization after the imaginal molt – or microimagos – short-winged imagos resulting from a shortened development. So far, not a single termite species is known to have lost the alate imago morph in either sex, contrary to a number of noneusocial cockroaches and many other hemimetabolous insects. However, in many termite taxa, neotenic reproductives may replace or supplement imago-derived ones. Neotenic (reproductive). Secondary reproductives that achieve sexual maturity without first reaching the alate imago stage are neotenics. Neotenics retain immature traits, such as wing buds,
2
Caste: Termites
Caste: Termites, Fig. 1 Diversity of termite castes. (a) Glyptotermes sp., Kalotermitidae (Sasaima, Colombia). Alates, two soldiers (da
Data Loading...
