The antpower is a unit of power, named by analogy with the more usual horsepower.
It can be estimated that one ant can generate 0.000015 watts (on the basis that one strong ant can lift 50 times its weight). It follows that it takes 67 million ants to generate a kilowatt, and about 51 million ants to generate one horsepower.
The conversion factor is therefore 1 hp = 51 Map.
Note: the antpower is not a SI unit, and should not be used in scientific articles if one wants to be taken seriously. But it can be used to show with efficacy how strong an ant really is.
The original calculation was as follows (quoted with explicit permission from the original author, but with corrections made by Wikipedia), from a discussion about hypothetical ant-powered power plants:
Start with a 3-milligram ant—about typical for a leafcutter, which is commonly shown lifting much larger leaves. Ants can lift 10 to 50 times their weight; being generous, let's say these ants were selected from the high side of that, and can thus lift 0.15 grams each. And let's also say the ant would need exactly 1 second to lift this weight [through a distance of 1 cm].
So, an ant could generate 0.00015 kg × 1 g × 0.01 m—or about 0.000 015 joule—per second, which is 0.000 015 watts—or about 0.000 000 02 horsepower. Inverting that, you'd need about 50 [million] ants to generate one horsepower, assuming perfect conversion of lifting power to whatever output form (electricity, rotary motion) you desire. In reality, conversion losses would multiply that.
When you consider the volume needed to store, harness, feed, motivate, et al. that many ants, it might be more efficient—to say nothing of far cheaper—to get that 1 horsepower from a horse.