Online Copy Abstract Aim: Methodology: Results: Interpretation: The holistic management of pink bollworm is possible only after uncovering the underlying mechanism/s of pink bollworm resistance. The present study was carried out for investigating the effect of Cry2Ab toxin on alkaline phosphatase activity and expression of its isoforms in midgut of Pectinophora gossypiella. Resistant and susceptible pink bollworm larval populations were subjected to Cry2Ab bioassays using F1 larvae in a 21 days diet-incorporation method. The total midgut protein was estimated by Bradford method. Alkaline phosphatase activity was estimated in midgut homogenates, Non-denaturing SDS-PAGE and Native polyacrylamide gel electrophoresis was performed by the following standard procedures. The study showed increased alkaline phosphatase activity in pink bollworm midgut is correlated with insect resistance in response to Cry2Ab. The non-denaturing SDS-PAGE analysis of pink bollworm midgut alkaline phosphatase isozymes had differential banding patterns in resistant and susceptible populations. Yavatmal (R1), Hingoli (R4) and Parbhani (R5) showed similar banding patterns ranging from 65-95 kDa; Guntur (R2) and Hingoli (R3) showed near similar banding patterns ranging from 70-95 kDa; whereas susceptible population showed banding pattern in the range of 50-70 kDa. The expression profiles of alkaline phosphatase isomers in resistant and susceptible populations can be utilized as a biomarker to aid for the screening of PBW infected Bt -cotton fields and development of pink bollworm management strategies. Key words: Alkaline Phosphatase, Cry2Ab, Insect resistance, Pectinophora gossypiella, SDS-PAGE 709-715 Vol. 43 2022 September © Triveni Enterprises, Lucknow (India) How to cite : Chinna Babu Naik, , T.D. Saonerkar, N. Chandrashekar, P.P. Pusadkar, S. Kranthi, P. Verma, S.H. Kumbhare, N.G. Narkhedkar and Y.G. Prasad: Biochemical characterization of alkaline phosphatase in midgut of Cry2Ab dosed, pink bollworm, Pectinophora gossypiella (Saunders). J. Environ. Biol., 43, 709-715 (2022). V. Journal of Environmental Biology p-ISSN: 0254-8704 • e-ISSN: 2394-0379 • CODEN: JEBIDP Biochemical characterization of alkaline phosphatase in midgut of Cry2Ab dosed, pink bollworm, Pectinophora gossypiella (Saunders) Received: 13.07.2021 Revised: 17.11.2021 Accepted: 10.12.2021 1 1 2 1 1 1 1 V. Chinna Babu Naik *, T.D. Saonerkar , N. Chandrashekar , P.P. Pusadkar , S. Kranthi , P. Verma , S.H. Kumbhare , 1 1 N.G. Narkhedkar and Y.G. Prasad 1 Division of Crop Protection, ICAR-Central Institute for Cotton Research, Nagpur-440 010, India 2 Division of Crop Improvement, ICAR-Central Institute for Cotton Research, Nagpur-440 010, India *Corresponding Author Email : chinnaenton@gmail.com Journal website : www.jeb.co.in « E-mail : editor@jeb.co.in Journal of Environmental Biology Triveni Enterprises (Educational Services Set-up) JEB ® DOI : http://doi.org/10.22438/jeb/43/5/MRN-2069 Original Research Pink ballworm resistant and susceptible larval populations were subjected to Cry2Ab toxin -1 The Cry2Ab toxin LC ranged from 0.461 to 1.285 μg ml 50 Alkaline phosphatase activity of lab susceptible population was 4.88 fold lower than the field population having least LC and 3.10 fold lower than that with the highest LC 50 50 ALP activity was estimated in midgut homogenates. ALP activity in PBW midgut increased was correlated with insect resistance in response to Cry2Ab toxin ØNon-denaturing SDS-PAGE analysis of PBW midgut ALP isozymes had differential banding patterns in resistant and susceptible populations ØALP activity and expression patterns of ALP isozymes resulting from resistant and susceptible PBW midgut contents can be explored as biomarker for screening the PBW populations from the infected fields of Bt-cotton