DECIPHERING DIAPAUSE AND THE OCCURRENCE OF DIAPAUSE PHENOTYPES OF Tetranychus urticae IN BRAZIL

• Grant number: 24/00312-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2024
• End date: February 28, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Raphael de Campos Castilho
• Grantee: Júlia Jantsch Ferla
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Diapause occurs in several arthropodes as a strategy used to overcome unfavorable conditions representing a fitness threat. It is characterized by a physiological condition that leads to an arrest of development of organisms adapted to respond to predicted seasonal environmental variations. Diapause is a common event reported in spider mites (Tetranychidae), including the two-spotted spider mite Tetranychus urticae Koch. This phytophagous mite is known to undergo facultative reproductive diapause, which enables it to overcome winter temperatures in temperate regions of the world. Recently, a T. urticae strain able to go into diapause was found for the first time in Brazil, associated with papaya in Espirito Santo and Bahia state. This is unusual in tropical regions where temperature and day length are not greatly reduced during winter, in comparison with temperate areas. Aspects regarding the adaptive potential are considered crucial, to determine the possibility to manage the occurrence of this process or to counteract it. Thus, the aim of this work is to investigate the responsiveness of Brazilian populations of T. urticae to the known environmental stressors that trigger diapause in this mite species. We will also investigate the mechanisms involved in diapause initiation and maintenance. Such approaches will lead to the identification of molecular and biological markers for the characterization of the reproductive diapause in T. urticae. To do this, we will compare the responsiveness of T. urticae in different mite strains and to assess the role of maternal effects on diapause induction as well as DNA methylation, metabolites, proteins and lipids. We will also compare the expression rate of the candidate genes through all development stages. The molecular and biological markers identified will be further used in the characterization of mite phenotypes occurring in natural populations, particularly the phenotypes observed in the populations associated with papaya plantations in the states of Bahia and Espírito Santo.