Banca de DEFESA: EDIVÂNIA MATIAS DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : EDIVÂNIA MATIAS DA SILVA
DATE: 16/02/2023
TIME: 09:00
LOCAL: Rio Largo
TITLE:

 

LETHAL AND SUBLETAL EFFECTS OF NAPHTOQUINONE ANALOGS AGAINST Mononychellus tanajoa (Bondar, 1938) (ACARI: TETRANYCHIDAE), PEST PRESENT IN CASSU (Manihot esculenta Crantz).

 

KEY WORDS:

Key words: Cassava green mite. Naphthoquinone compounds. Acaricides.

PAGES: 83
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitossanidade
SPECIALTY: Defesa Fitossanitária
SUMMARY:

The cassava green mite, Mononychellus tanajoa (Bondar 1938) (Acari: Tetranychidae), is of great importance and can cause considerable losses in cassava crops. The control of the green mite, M. tanajoa is difficult, since until now there are no acaricides registered for this pest in the cassava crop. Natural and synthetic naphthoquinone compounds stand out for having varied biological activities, including acaricides. Therefore, the present work aimed to analyze the lethal and sublethal effects related to the repellent effect, instantaneous population growth rate and residual effect of natural and synthetic naphthoquinone compounds on the green mite, M. tanajoa in the cassava crop. Lethal concentrations of naphthoquinones were estimated by Probit analysis. To evaluate the repellent effect, cassava leaf discs were sprayed with water + 2%DMSO (control) or with the treatments (CLs 5, 25, 50, 75, 90 and 95) of the nine naphthoquinone compounds. Then, they were placed in a Petri dish and connected by a coverslip, with the treated leaf disc on one side and the control on the other. In the center of the coverslip 10 females of M. tanajoa were released and after 24 hours the number of females in each disc was evaluated, 15 repetitions were performed per treatment. For the instantaneous population growth rate (ri), cassava leaf discs were immersed with the compounds (CLs 5, 25, 50, 75, 90 and 95) and the control. Five females were transferred per disc and ten replicates were used per treatment. After 10 days, the total number of mites was counted. To evaluate the residual effect, cassava seedlings were sprayed with the LC95 of the compounds. After 2 h of application and during the periods of 1, 2, 4, 8 and 16 days after application, leaf discs were removed, placed in Petri dishes and transferred 10 females of M. tanajoa, the mortality assessment was 72 h after the application. lockdown. Among the naphthoquinones, the derivative 2-(4-((5-Methyloxazol-3-yl)-methylsulfonyl)-phenylamino)-naphthalene-1,4-dione) (C7) was the most toxic, followed by ((4 -Pyridin-3-yl)-methylsulfonyl)-phenylamino)-naphthalene-1,4-dione (C6), and by 2-bromo-naphthalene-1,4-dione (C4), with LC50 values (IC 95%) of 3.08; 5.29 and 6.33 µL/mL and LC90 (95% CI) 16.21; 24.53 and 34.31 µL/mL, respectively. Therefore, the following order of acaricidal activity was observed against the green mite, M. Tanajoa C7 > C6 > C4 > C2 > C3 > C1 > C8 > C9 > C5 for both LC50 and LC90. The viability of M. tanajoa eggs was affected after the application of Naphthoquinones (C1-C9). Based on LC50 and LC90 values 2-(4-((5-Methyloxazol-3-yl)-methylsulfonyl)-phenylamino)-naphthalene-1,4-dione) (C7) was the most toxic, followed by ( (4-Pyridin-3-yl)-methylsulfonyl)-phenylamino)-naphthalene-1,4-dione (C6), 2-bromo-naphthalene-1,4-dione (C4) and by (N'-(1, 4-Dihydro-1,4-dioxonaphthalen-2-yl)-isonicotinoylhydrazide) (C8). For these compounds, interference in the viability of eggs was observed, as well as which were the smallest amounts of the product to cause 50% and 90% of mortality in the population with estimated LC50 values of 5.77, 6.15, 6.62 and 8.16 µg/mL, and LC 90 with values of 23.77; 18.41; 20.38 and 31.55, respectively. Therefore, the following order of acaricidal activity was observed in eggs of the green mite, M. Tanajoa C7 > C6 > C4 > C8 > C9 > C5 > C1 > C2 > C3. Our studies showed that C7, C6 and C4 showed efficient results regarding the toxicity of eggs and adults of M. tanajoa. The structure-activity relationships between the most promising compounds show that the presence of sulfonamide-type substituents linked to position 2 of the quinone nucleus (C7 and C6) allowed an increase in activity by 5.5 and 3.2 times, respectively, compared to 1,4-naphthoquinone itself (C1). On the other hand, the inclusion of the bromine atom at position 2 of 1,4-naphthoquinone was able to increase the activity by 2.7 times compared to C1. In addition, C8 (N'-(1,4-Dihydro-1,4-dioxonaphthalen-2-yl)-isonicotinoylhydrazide) and C9 (N-Isonicotinoylhydrazone-[2-hydroxy-3-(3-methyl-2-butenyl) )]-1,4-naphthoquinone) showed that the change of the hydroxyl group or one of the carbonyl groups of the basic nucleus of naphthoquinones (C2 and C3 compounds) by a polytrogenated group, be it a 2-N-acylhydrazide (C8) or a 1-N-acylhydrazone (C9) contributed to increase the toxicity of the compounds in the eggs in relation to the adult phase of M. Tanajoa, with the presence of the 2-N-acylhydrazone group being more efficient than 1-N-acylhydrazone. The ADME in silico properties of naphthoquinone compounds showed potential to develop as good candidates for acaricides, following Lipinski's rule of five. Repellent effect was observed for natural naphthoquinones, lausone (C2) and lapachol (C3) only from CLs 90 and 95 respectively. However, for C8 and C9 naphthoquinones synthesized from natural compounds, repellency was observed from LC25. In relation to the other synthetic naphthoquinones 1,4 Naphthoquinone (C1), 2-bromo-1,4-naphthoquinone (C4), 2, 3-Dichloro-1, 4-naphthoquinone (C5), 4-Pyridin-3-Il) (Methylsulfonyl) Phenylamino) Naphthalene 1,4-Dione (C6) and 2-(4-((5-Methyloxazol-3-yl) Methylsulfonyl) Phenylamino) Naphthalene-1,4-Dione) (C7) repellent effect was observed M. tanajoa when using contractions referring to CLs 75, 90 and 95. The instantaneous population rate for all compounds decreased with increasing concentrations. Compounds C5 in LC 90 and 95 and compound C7 in LC 95 were able to stabilize the population of M. tanajoa (ri=0). None of the natural compounds C2 (lausone) and C3 (lapachol) tested caused the instantaneous rate of population growth to be negative, however, there was a proportional reduction in the reproduction of mites, with increasing concentrations used. However, compounds C8 and C9 that were synthesized from lausanne and lapachol, respectively, were able to negatively destabilize the population of M. tanajoa. In the residual effect, it was observed that only C3 ([2-Hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthatoquinone - Lapachol) showed moderate residual persistence (mortality ≥ 33% up to 16 days after the application of the products) and the naphthoquinone compounds C1, C2, C4, C5, C6, C7, C8 and C9 show slight persistence (mortality ≥ 27% up to 8 days after the application of the compounds). Naphthoquinones may have potential for the development of acaricides. However, further studies should be carried out to assess the expense and efficiency of these naphthoquinones on a wide variety of pests in the field.

 

 

 

 

BANKING MEMBERS:
Presidente - 1642163 - EDMILSON SANTOS SILVA
Interno(a) - 2337920 - ROSEANE CRISTINA PREDES TRINDADE
Externo(a) à Instituição - ADEILDO JUNIOR DE OLIVEIRA - UFAL
Externo(a) à Instituição - JANDIR CRUZ SANTOS
Externo(a) à Instituição - MÉRCIA ELIAS DUARTE - EMBRAPA