Life Cycle of Insects-I

It seems easy to tell a child that eggs hatch into larvae, larvae mature into pupae and pupae into adult forms, while explaining how a butterfly exhibits different forms in its life-cycle. We tend to explain that any life-cycle is a progress along a developmental pathway. How fast or how slow an insect completes its life-cycle? It can be a great question.

 

While talking about the things that control their polymorphic nature, it is difficult to conclude whether the time is programmed in their genes or environmental changes are necessary for the expression of such genes? Environmental changes pertain to seasonal changes in which the parameters like photo-period, temperature and humidity change.

 

Availability of  'FOOD' is  most important. Nature has programmed everything. We find that when FOOD is abundant in the environment than only the feeding forms (i.e. larvae) emerge. So if we try to find examples we will come to conclude that life-cycles are regulated in the nature. When the feeding forms mature into reproducing forms; i.e., adults, the growth of their population is constrained by abundance of predators which feed on them. 

My Memory Note

I remember one of my teachers, Mr. A.K. Thakur, he was not a teacher by profession was a govt. consultant. He had deep interest in microbiology. It happened that I was acquainted to him and got an opportunity to attend his class, in a coaching institute. He stressed on availability of 'FOOD' in the environment. His pronunciation 'F' pronounced as 'ph' with an undue stress was peculiar . You can't laugh in the class, but when you are out, there are no any constraints! Ha ha.... "No Any", it was his commonly used phrase. He was a fatherly personality, it always felt like my father was teaching me, when he used to turn his back while teaching.

 A species response in  adverse conditions reflects its adaptation to factors such as season length, food supply, competition and natural enemies. Timing to develop resistance to an adversity can be modified by numerous ways such as slower development, arrested development, movement to sheltered sites. Life cycle responses are understood in terms of adaptation for seasonal coincidence(synchrony), tolerance of differences or choice of alternatives (flexibility), programmed differences (variability). The synchrony, flexibility and variability depend chiefly when and how conditions constraint growth and development (Danks 1987, 1991,1992).