Statement 2 is completely incorrect because Dalapon (2,2-dichloropropionic acid) is a systemic chlorinated aliphatic herbicide (not an insecticide) that is readily biodegradable by soil microorganisms with a typical soil persistence of only 2 to 4 weeks (it does not persist for 9 months).

• Chlorinated hydrocarbon insecticides persist in the soil for a longer period: True statement (DDT/Dieldrin persist for years).
• Dalapon insecticide persist up to 9 months in the soil: Factually incorrect statement.
• Organophosphates and Carbamates persist not beyond 4 months in soil: True statement (rapidly hydrolysed in soil).
• All of the above: Incorrect.

• Othmar Zeidler first synthesized DDT in 1874 as a chemistry doctoral student in Germany.
• Paul Hermann Müller discovered the insecticidal properties of DDT in 1939, earning the 1948 Nobel Prize in Physiology or Medicine.
• Michael Faraday first synthesized Benzene Hexachloride (BHC / HCH / 1,2,3,4,5,6-hexachlorocyclohexane) in 1825 by the addition of chlorine to benzene in the presence of sunlight.
• Kukenthal was an early pesticide chemist involved in synthetic organochlorines, but did not discover BHC.

• Duboisia hopwoodii is the source of pituri, containing nicotine and d-nornicotine.
• Anabasis aphylla is the botanical source of anabasine (neonicotinoid alkaloid).
• Ryania speciosa is the botanical source of ryanodine (ryanoid insecticide).
• Rotenone is a naturally occurring isoflavonoid insecticide isolated from the roots of Fabaceae plants belonging to the genera Derris (such as Derris chinensis, D. elliptica, D. trifoliata) and Lonchocarpus.

• Nereistoxin is a natural neurotoxic substance isolated in 1934 by Japanese pharmacologist Dr. Shingo Nitta (Dr. Nitta) from the marine segmented worm Lumbriconereis heteropoda (Nereis).
• Japanese fishermen had long noticed that carnivorous flies and ants dying upon contacting dead bait worms.
• Nereistoxin acts as a synaptic blocking agent at nicotinic acetylcholine receptors (nAChR), leading to the development of synthetic nereistoxin analogues, most notably cartap hydrochloride (Padan) and bensultap.
• Dr. Rembold is renowned for research on neem azadirachtin, and Dr. Williams worked on juvenile hormone.