I really do not know what this bot is trying to accomplish, but it looks rather pointless:

66.167.105.59 - - [10/Mar/2008:04:47:50 +0100]
"POST / HTTP/1.1" 403 210 "-" "BioSearch"
66.167.105.59 - - [10/Mar/2008:04:47:51 +0100]
"POST /robots.txt HTTP/1.1" 403 220 "-" "BioSearch"

You would only use POST for submitting form data, but not retrieving data. Apart from that, the request order is wrong: A bot should first ask for robots.txt and then, depending on the outcome, either go away or start indexing.

Unfortunately the netblock, where this brainless wonder resides, does not reveal any details about the bot’s owner:

[rwhois.covad.net]
%rwhois V-1.5:003fff:00 rwhois.covad.com (by Network Solutions, Inc. V-you-guess)
network:Class-Name:network
network:Auth-Area:66.167.0.0/16
network:ID:NETBLK-NONE-66-167-0-0.66.167.0.0/16
network:Network-Name:NONE-66-167-0-0
network:IP-Network:66.167.0.0/16
network:In-Addr-Server;I:ns3.covad.com
network:In-Addr-Server;I:ns4.covad.com
network:IP-Network-Block:66.167.0.0 - 66.167.255.255
network:Org-Name:Covad Communications
network:Street-Address:110 Rio Robles
network:City:San Jose
network:State:CA
network:Postal-Code:95134
network:Country-Code:US
network:Tech-Contact;I:ipadmin covad.com
network:Admin-Contact;I:ipadmin covad.com
network:Created:20030508150409000
network:Updated:20041506165200000

The rDNS of the offending ip address is not more talkative either:
h-66-167-105-99.lsanca54.dynamic.covad.net
This reads to me like Los Angeles/California.

Although there is a company in California called Biosearch Technologies, they are unrelated to the bot, as they are only offering products derived from their biological research and are based in the San Francisco area. So it seems to be just a broken anonymous bot which is safe to block.