Question

Why should biological control of pests and pathogens be preferred to the

conventional use of chemical pesticides? Explain how the following microbes act

as biocontrol agents:

a. Bacillus thuringiensis

b. Nucleopolyhedrovirus​

Answer 1

Explanation:

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ʙɪᴏʟᴏɢɪᴄᴀʟ ᴄᴏɴᴛʀᴏʟ ᴏғ ᴘᴇsᴛs ᴀɴᴅ ᴘᴀᴛʜᴏɢᴇɴs ɪs ᴘʀᴇғᴇʀʀᴇᴅ ʙᴇᴄᴀᴜsᴇ:

ɪ. ᴛʜᴇ ᴄʜᴇᴍɪᴄᴀʟs ᴄᴀᴜsᴇ ᴘᴏʟʟᴜᴛɪᴏɴ ᴏғ ᴡᴀᴛᴇʀ ʙᴏᴅɪᴇs ᴀs ᴡᴇʟʟ ᴀs ɢʀᴏᴜɴᴅ ᴡᴀᴛᴇʀ, ʙᴇsɪᴅᴇs ɢᴇᴛᴛɪɴɢ sᴛᴏʀᴇᴅ ɪɴ ᴛʜᴇ ᴘʟᴀɴᴛs.

ɪɪ. ᴛʜᴇ ᴄʜᴇᴍɪᴄᴀʟs ᴀʀᴇ ᴛᴏxɪᴄ ᴛʜᴜs ᴇxᴛʀᴇᴍᴇʟʏ ʜᴀʀᴍғᴜʟ ᴛᴏ ʜᴜᴍᴀɴ ʙᴇɪɴɢs ᴀɴᴅ ᴏᴛʜᴇʀ ᴀɴɪᴍᴀʟs.

ᴀ. ʙᴀᴄɪʟʟᴜs ᴛʜᴜʀɪɴɢɪᴇɴsɪs: ʙ. ᴛʜᴜʀɪɴɢɪᴇɴsɪs ᴛᴏxɪɴ ɢᴇɴᴇs ᴡʜᴇɴ ɪɴᴛʀᴏᴅᴜᴄᴇᴅ ɪɴᴛᴏ ᴘʟᴀɴᴛ, ʙᴇᴄᴏᴍᴇ ʀᴇsɪsᴛᴀɴᴛ ᴛᴏ ᴀᴛᴛᴀᴄᴋ ʙʏ ɪɴsᴇᴄᴛ ᴘᴇsᴛs. ᴛʜᴇʏ ᴀʀᴇ ᴀᴠᴀɪʟᴀʙʟᴇ ɪɴ sᴀᴄʜᴇᴛs ᴀs ᴅʀɪᴇᴅ sᴘᴏʀᴇs, ᴡʜɪᴄʜ ᴀʀᴇ ᴍɪxᴇᴅ ᴡɪᴛʜ ᴡᴀᴛᴇʀ ᴀɴᴅ sᴘʀᴀʏᴇᴅ ᴏɴᴛᴏ ᴠᴜʟɴᴇʀᴀʙʟᴇ ᴘʟᴀɴᴛs. ᴡʜᴇɴ ᴛʜᴇʏ ᴀʀᴇ ᴇᴀᴛᴇɴ ʙʏ ᴛʜᴇ ɪɴsᴇᴄᴛ ʟᴀʀᴠᴀᴇ, ᴛʜᴇ ᴛᴏxɪɴ ɪs ʀᴇʟᴇᴀsᴇᴅ ɪɴ ᴛʜᴇ ɢᴜᴛ ᴡʜᴇʀᴇ ɪᴛ ʙᴇᴄᴏᴍᴇs ᴀᴄᴛɪᴠᴇ ᴀɴᴅ ᴋɪʟʟs ᴛʜᴇ ʟᴀʀᴠᴀᴇ. sᴘᴇᴄɪғɪᴄ ʙᴛ ᴛᴏxɪɴ ɢᴇɴᴇs ᴏʙᴛᴀɪɴᴇᴅ ғʀᴏᴍ ʙ. ᴛʜᴜʀɪɴɢɪᴇɴsɪs ᴀʀᴇ ᴜsᴇᴅ ɪɴ sᴇᴠᴇʀᴀʟ ᴄʀᴏᴘ ᴘʟᴀɴᴛs ᴡʜɪᴄʜ ᴍᴀᴋᴇ ᴛʜᴇᴍ ʀᴇsɪsᴛᴀɴᴛ ᴛᴏ ɪɴsᴇᴄᴛ ᴘᴇsᴛ.

ʙ. ɴᴜᴄʟᴇᴏᴘᴏʟʏʜᴇᴅʀᴏᴠɪʀᴜs: ᴛʜᴇsᴇ ᴠɪʀᴜsᴇs ᴀʀᴇ ᴇxᴄᴇʟʟᴇɴᴛ ᴄᴀɴᴅɪᴅᴀᴛᴇs ғᴏʀ sᴘᴇᴄɪᴇs-sᴘᴇᴄɪғɪᴄ, ɴᴀʀʀᴏᴡ sᴘᴇᴄᴛʀᴜᴍ ɪɴsᴇᴄᴛɪᴄɪᴅᴀʟ ᴀᴘᴘʟɪᴄᴀᴛɪᴏɴs. ᴛʜɪs ɪs ᴇsᴘᴇᴄɪᴀʟʟʏ ᴅᴇsɪʀᴀʙʟᴇ ᴡʜᴇɴ ʙᴇɴᴇғɪᴄɪᴀʟ ɪɴsᴇᴄᴛs ᴀʀᴇ ʙᴇɪɴɢ ᴄᴏɴsᴇʀᴠᴇᴅ ᴛᴏ ᴀɪᴅ ɪɴ ᴀɴ ᴏᴠᴇʀᴀʟʟ ɪɴᴛᴇɢʀᴀᴛᴇᴅ ᴘᴇsᴛ ᴍᴀɴᴀɢᴇᴍᴇɴᴛ (ɪᴘᴍ) ᴘʀᴏɢʀᴀᴍᴍᴇ.