There's any chance we could have a insect themed sentai ?

Maybe but the problem is they need a toy gimmick to sale

But the plot could be like the two b-fighters ?

Doesn't matter. There needs to be a toy to sell.

How long does it take to make subs?

Completely depends on the person making the subs.

What is Super Sentai's attitude era (again, WWE)

You know darker and more violence era of Super Sentai

You could totally work in a gimmick with bugs, for example: small jars with different insect figures in them, which could then be place in the morpher, and robo, or having bugs stuck in amber which could then be placed in the morpher/robo.

I was Bored so I tired.
 

Let's see, a gimmick:

Sixth Ranger will be Arachnid based, because they're always "special" and "different"
the main five's morphers could be bug-catching nets, because we've seen weirder morphers at this point so it's allowed.
Their main weapons could be handheld pincers like the KuwagaRaiger's Stag Breaker, and their other sub weapon would be laser antennas or something.
Red Ranger would be Ant based, which leads into
the Enemy group being either based off of Wasps solely or various pests or insects with bad reputations like roaches or locust and the Wasps being the generals/high-caste of the group, and an immobile queen being the head villain (until her princess daughter offs her mid-season)
There'll be a rogue wasp zord that both the Rangers and the Enemies use to combine with their mechs
Mid-season upgrade will either be an exoskeleton or some sort of pollen armor (why not both)
Final zord will be like a creepy hive, shooting out small robots to attack enemy giants from various hexagon hole located all over it.
Catchphrase will be "Buzzing evil into submission" or something equally corny
Auxiliary Rangers based off of larvae, all white and numbered "EX"
Team cannon resembles a Caterpillar, like one a bunch of ants just killed and are taking back to the hive.
Also, possible metamorphoses super armor which requires either the Red Ranger, sixth ranger, or maybe all the rangers in different episodes to be gone an entire episode so as to evolve into a Butterfly super mode, complete with a Proboscis sword that doubles as a gun and energy wings that release explosive powder when flapped.

Side-note, one ranger must be addicted to sap, and another must be an extreme rules-nazi because of how organized/coordinated some insect species are.

I think would be better if the sixth ranger should be a herakles beetle meanwhile the spider and scorpion are villains.The main villains could be like jamahl and melzard.