AN ASSESSMENT ON NATURAL REGENERATION OF Gymnema sylvestre, A RARE MEDICINAL PLANT

Abstract

Antlions belong to the order Neroptera, class Insecta. They belong to thefamily Myrmeleontidae. The anti ion name is applied to the larval stage ofthese insects. Adult insects of this family have four lace-like wings, similar todragonflies. Pit building behavior is characteristic to the genus Myrmelon.There are different size antlions and they appear to consume different preyaccording to preliminary observations. Hence the hypothesis is to establishwhether antlions have the ability to select their prey, and whether their levelof hunger and their own body size affect prey selection.

Present study was conducted in Khao Chong Wildlife Extension andConservation Center, Trang Province, Thailand.

In order to identify the predatory behavior of antlions, anti ions were collectedfrom the field and kept for about six hours for rest and recuperation, andallowed to make their pit. The experiment was conducted at roomtemperature. An ant was dropped in the center of the pit and resultinginteractions were observed. Observation of the antlion was started as soon asthe prey dropped in the center of the pit and ended with either the prey deador escaped free from the pit.

In order to check whether antlions select their prey according to the prey size,starvation level and their own size, collected antlions were categorized intotwo groups according to body size (0.5-1.0 em long and <1.0 em long). Bothsize classes were sub-divided in to four groups of 15 individuals, and theywere fed with ants. After feeding, each group was starved for a differentlength of time (0 hrs (level 0), 12 hrs (level 1), 24 hrs (level 2), and 36 hrs(level 3), prior to commencing the feeding experiment. Three types of preywere used for this experiment.

From the collected data predatory success for small and large antlions wascalculated for each treatment. One sample T - tests were run in order tocheck whether there was a significant difference in predatory successbetween three types of prey at the same starvation level. In order to identifythe relationship between predatory action and starving level for small antIionsand large antlions a contingency analysis was conducted.

In order to identify the predatory action by prey type a second contingencyanalysis was carried out. Large antlions always attacked small prey andattacked large prey less frequently, but small antIions attack all prey withequal frequency.

According to results larger antlions attack more large prey as starvation levelincreased, but small antlions try to attack all prey without regard to size.However, predatory success was low for small antlions, when they attackedlarger prey. Smaller antlions may be less experienced in assessing prey sizeor likelihood of success.

It was found that the selected time scale for the starvation levels was toolong. Hence, it was difficult to compare the predatory success of differentstarvation levels.