Mumbai, Aug. 14 (PTI): Can male bees and wasps, which are normally considered lazy, be made to work like feeding the larvae? Yes, say biologists of the Indian Institute of science, Bangalore.

"Males do little more than transferring their sperm to virgin queens while all the work involved in nest building, brood care and, finding and processing food is done by the females .But our experiments with the males of bees and wasps of the order Hymenoptera have proved that they could be made to do some work like feeding the larvae," Prof. Raghavendra Gadagkar of Biology section of IISc, said.

The best known insect societies are those of ants, bees and wasps all of which belong to the order Hymenoptera.

Individuals in these species organize themselves into colonies consisting of tens to millions.

But a less studied but equally intriguing aspect of these hymenopteran societies is that they are feminine monarchies - there are queens but no kings and all workers are females involved in nest building, brood care and foraging.

Males do little more than transferring their sperm to virgin queens.

Using the primitively wasp (Ropalidia marginata) and the important task of feeding larvae as an example of work, "we have recently made a novel attempt to understand the secret behind the well-brood care and finding and processing food is done by the females," Gadagkar said.

In the colony where the workers are always females and males do not participate in nest building, or brooding or foraging , the scientists through their experiments found that although males were not as efficient as females at feeding larvae, they seemed capable of doing enough for natural selection to promote the male workers if there were not other factors preventing it.

Scientists Ruchira Sen and Gadagkar used some of the hypotheses like males are incapable of feeding larvae, males never get access to enough food to satisfy themselves and have something left over to offer to the larvae, and females are so much more efficient at feeding larvae that they leave no opportunities for the relatively inefficient males to do so.

Sen said she offered experimental colonies excess food. This resulted in a marginal amount of feeding of the larvae by males, thus disproving the hypothesis that males are incapable of feeding larvae.

Then she removed all the females from some colonies and left the males alone with hungry larvae. This experiment was a non-starter because males cannot forage and find food in the absence of females. Sen overcame this problem by mastering the art of tenderly and patiently hand-feeding the males. And she gave them more food than they could themselves consume so that they might feed larvae if they could.

Thus males can feed larvae and will do so if they are given an opportunity. It therefore appears that males do not feed larvae under natural circumstances because they do not have access to enough food and/or because females leave them few opportunities to do so, he says.

There are several lines of evidence to suggest that the males were not merely dumping unwanted food but that they were actively seeking out the most appropriate larvae and feeding them "deliberately".

"But it must be emphasized that from the point of view of the larvae, males were quite inefficient compared to the females. Apart from the fact that males fed only the oldest larvae and ignored all the young larvae, it turned out that many of the larvae under all male care died," the scientists said.

"These studies open up a major evolutionary puzzle-- why has natural selection not made the males more efficient" Gadagkar said .

Scientists said feeding larvae by females is more complex compared to that of males, the process of feeding larv e by females appeared to be more complex because it was accompaniedmore often by other behaviours.

These included fanning wings while entering the larval cell, antennal drumming of the larvae during feeding and withdrawing from the larval cell with a rapid jerk of the body which was sometimes performed synchronously by many females.

Females fanned their wings significantly more often while feeding larvae in the pre-grooming phase than males.