Biological and behavioral responses of Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) to tomato plants infected with Tomato chlorosis virus (ToCV) and Tomato severe rugose virus (ToSRV) and stylets activities associated with inoculation of ToCV

Author(s)

Nathalie Kristine Prado Maluta

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2017-02-20

Examining board members

Joao Roberto Spotti Lopes; José Maurício Simões Bento; Alberto Fereres Castiel; André Luiz Lourenção; Jorge Alberto Marques Rezende

• Advisor: Joao Roberto Spotti Lopes

Abstract

Several phytoviruses are capable of influencing the behavior and biological development of their insect vectors in order to promote their spread among host plants, but information about the effects of viral infections on whiteflies Bemisia tabaci (Genn.) is not available, since it is a species complex, which transmits vírus belonging to different genus with distinct transmission modes. Considering B. tabaci importance as a pest and a vector and the great damage caused to several crops due to the transmission of phytovirus, the present work had as objectives: a) To investigate the preference for landing and the arrestant behavior of B. tabaci MEAM 1 (Middle East-Asia Minor 1) in non-infected and infected tomato plants with semi-persistent crinivirus, Tomato chlorosis virus (ToCV) and the persistent-circulative begomovirus, Tomato severe rugose virus (ToSRV); b) To evaluate the direct and indirect effects of ToCV on the biological performance of B. tabaci MEAM 1 c) To compare the feeding behavior of non-viruliferous B. tabaci MEAM 1 in non-infected and ToCV or ToSRV-infected tomato plants using the Electrical Penetration Graph (EPG) technique; d) Correlate the stylets activities of B. tabaci MED (Mediterranean) with the inoculation of ToCV in tomato. It has been found that ToCV-infected plants do not exert an attraction on B. tabaci MEAM 1; there is a direct effect when the insect is viruliferous, however, this effect does not seem to favor the spread of ToCV. ToSRV has a direct effect that favors its dissemination, as viruliferous insects are more attracted to non-infected plants. The whitefly exhibits an arrestment behavior on non-infected plants, and tends to leave plants infected by ToCV or ToSRV, suggesting that such viruses reduce the nutritional quality of the host plant. In relation to the biological development, we observed a direct effect of ToCV only on the first ninfal instar, and a negative indirect effect on nymphal viability, since only 32% of the initial individuals reached adulthood in ToCV-infected plants contrasting with 77% in non-infected plants. In the EPG tests, it was verified that the infection of tomato plants by ToCV or ToSRV did not influence the feeding behavior of the vector in order to favor the transmission of these viruses, since it affected only parameters not related to the phloem. The transmission of ToCV is mainly associated to salivation in the phloem elements (waveform E1) (52,2% of infected plants), but may occur in a low proportion before E1 (3,5%). However, there is a greater efficiency of transmission when individuals perform several episodes of E1 + E2 (phloem sieve elements). The data obtained in this thesis help to clarify a little more about the complex relationships between B.tabaci and different phytovirus, and how the behavioral responses may vary depending on the mode of transmission. (AU)

• FAPESP's process: 12/24974-1 - Biological and behavioral responses of Bemisia tabaci biotype B in tomato infected plants with Tomato chlorosis virus (ToCV)
• Grantee: Nathalie Kristine Prado Maluta
• Support Opportunities: Scholarships in Brazil - Doctorate