Contents lists available at ScienceDirect Comparative Biochemistry and Physiology, Part B journal homepage: www.elsevier.com/locate/cbpb Tyrosine hydroxylase is crucial for pupal pigmentation in Zeugodacus tau (Walker) (Diptera: Tephritidae) He-He Zhang a,b,c,d,1 , Qi-Wen Zhang a,b,c,d , Atif Idrees a,b,c,d , Jia Lin a,b,c,d , Xue-Sen Song a,b,c,d, Q ng-E Jia,b,c,d , Ying-Gang Du e , Min-Lin Zheng a,b,c,d , Jia-Hua Chen a,b,c,d, ⁎ a Institute of Beneficial Insects, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou 350002, PR China b UN (China) Center for Fruit Fly Prevention and Treatment, Fuzhou 350002, PR China c State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fuzhou 350002, PR China d Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fuzhou 350002, PR China e Jia Si Xie Agricultural College, Weifang University of Science and Technology, Shouguang 262700, PR China ARTICLE INFO Keywords: Tyrosine hydroxylase Sclerotization Pigmentation 3-iodo-tyrosine Phenotypes Transcriptional levels ABSTRACT Tyrosine hydroxylase (TH) is the initial enzyme responsible for cuticle sclerotization and pigmentation in many insect species, but to date, no direct functional studies have focused on TH in Zeugodacus tau. Here, the 3336-bp full-length cDNA of TH was isolated from Z. tau, a notorious horticultural pest infesting fruits and vegetables. qRT-polymerase chain reaction revealed that ZtTH transcripts were highly abundant at the time of pupal tanning and during adult emergence and were expressed in the midgut, integument and head of molting larvae. The pupation and eclosion rates gradually decreased when the 1st-instar larvae were fed diets containing higher concentrations of the TH inhibitor 3-iodo-tyrosine (3-IT). Moreover, pupal weights were significantly decreased, and abnormal uncolored phenotypes were observed after 20 mg/g 3-IT was incorporated into the diet. In ad- dition, the suppression of TH function (mediated by RNA interference) led to a decrease in TH mRNAs and eclosion rates, accompanied by less-pigmented phenotypes. There was a severe impairment of larval-pupal cuticle tanning, leading to pupae with less yellowish pigment or that were completely white and transparent, when we injected 2 μL of 24.4 mM or 73.27 mM 3-IT into 3rd-instar larvae or prepupae. These results suggest that TH is an important enzyme for the normal growth and pupal pigmentation of Z. tau and that TH is a potential gene target for use in the control of Z. tau. 1. Introduction Pigmentation patterning is one of the most diverse and distin- guishable features of insect morphology, has long interested biologists and is of vital importance to the normal development or protection of the insect from exogenous physical injury (Andersen, 2010; Beadle and Ephrussi, 1936; Beadle, 1937; Ephrussi and Chevais, 1937). A variety of body colors and patterns reflect natural biodiversity and a number of physiological processes, including visual communication, adaptation (camouflage), behavior, and reproduction (Carroll, 2005; Hagen, 1992; True, 2003; Wittkopp and Beldade, 2009). In insects, body-color-pig- ment precursors and/or pigments are typically synthesized in the epi- dermal cells (pigments and/or their precursors used for cuticle con- struction and body-color formation are not limited to the cuticle, as increasing evidence points to their presence in the hemolymph, gut and other tissues), accompanied by a complex cascade of biochemical re- actions with end products incorporated into the hard exoskeleton, and subsequently become an integral part of the body (Whitten and Coates, 2017; Wittkopp and Beldade, 2009). This general simplified model is responsible for creating the astonishing diversity of insect coloration and patterning observed in nature (Lemonds et al., 2016). The most prominent colors observed in insects are black and brown, the pro- duction of which is attributed to the melanin synthesis pathway. This tanning pathway involves two distinct and complex processes: scler- otization and melanization (Sugumaran and Barek, 2016). The first step in the cuticle sclerotization and melanization (pigmentation) pathway is the hydroxylation of tyrosine (a monophenol) to produce 3,4-dihy- droxyphenylalanine (DOPA, an o-diphenol). Insects use melanization and sclerotization for cuticle coloration. For pigmentation, dopamine (conversion of DOPA to dopamine by DOPA decarboxylase, DDC) rather https://doi.org/10.1016/j.cbpb.2019.01.017 Received 19 October 2018; Received in revised form 25 January 2019; Accepted 28 January 2019 ⁎ Corresponding author at: Institute of Beneficial Insects, Plant Protection College, Fujian Agriculture and Forestry University, Fuzhou 350002, PR China. E-mail addresses: jhchen34@163.com, jhchen34@126.com (J.-H. Chen). 1 These authors contributed equally to the study. Comparative Biochemistry and Physiology, Part B 231 (2019) 11–19 Available online 05 February 2019 1096-4959/ © 2019 Elsevier Inc. All rights reserved. T