Experiments were conducted to determine the impact of water management strategies on populations of rice water weevil, Lissorhoptrus oryzophilus Kuschel. One experiment was conducted at the Delta Research and Extension Center during 2017 and 2018. The performance of chlorantraniliprole and thiamethoxam was evaluated in combination with flood removal of a field as a cultural control tactic for rice water weevil. Seed treatments significantly reduced rice water weevil populations at the prelood sample timing, only chlorantraniliprole reduced populations at the post-drainage sample timing. Overall, flood removal had little impact on rice water weevil management. An experiment was also conducted to determine the spatial and temporal distribution of rice water weevil larvae within a furrow irrigated rice production system. This experiment was established across eleven grower fields in major rice producing counties across the Mississippi Delta from 2017 to 2018. Fields were divided into three zones based on free standing water within that portion of the field between irrigation events. Rice water weevil larval populations were reduced in portions of the field that did not remain at two of the three sample timings. An experiment was conducted at the Delta Research and Extension Center during 2017 to determine the impact of various water management strategies and insecticide seed treatments on rice water weevil populations. The –10 cm free standing water management strategy significantly reduced rice water weevil populations from the untreated control. Chlorantraniliprole had significantly higher yields across all water management strategies compared to other seed treatments and the untreated control.

Made available in DSpace on 2014-06-11T19:28:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-04Bitstream added on 2014-06-13T19:16:46Z : No. of bitstreams: 1 takada_hm_me_botfca.pdf: 587174 bytes, checksum: 68fcfeed820ef9c331817e76b2f9fab3 (MD5) / Com o objetivo de avaliar a patogenicidade e a virulência de fungos entomopatogênicos ao gorgulho aquático do arroz irrigado, Oryzophagus oryzae, foram testados 24 isolados de Metarhizium anisopliae e 2 de Beauveria bassiana. Os bioensaios foram realizados em condições controladas (26+1°C e 12 horas de fotofase). Nos testes para determinar a concentração adequada, a espécie M. anisopliae, isolado E9, apresentou maior patogenicidade quando comparado aos isolados de B. bassiana. A mortalidade confirmada, provocada pelo M. anisopliae, teve início no 4º dia, aumentando em seguida até estabilizar-se no 8º dia. Para a seleção dos isolados de M. anisopliae, adultos dos insetos foram inoculados com 1 mL de suspensão fúngica a 5x108 conídios/mL (1,6x104 conídios/mm2). Todos os isolados foram patogênicos ao inseto, sendo que a mortalidade variou entre 9,3 e 85,3 %. Os isolados de M. anisopliae mais patogênicos foram CB-103, CB-104, CB-233, E9 e CB-10. No teste de produção, os isolados CB-104, CB-233 e CB-103 foram superiores ao padrão E9, apresentando-se promissores para a utilização no controle de Oryzophagus oryzae. / Strains of Metarhizium anisopliae and Beauveria bassiana were evaluated concerning their pathogenicity and virulence for control of the rice water weevil, Oryzophagus oryzae. Bioassay conditions were 26+1ºC and 12 h. light. M. anisopliae (E9 strain) was been more pathogenic than two Beauveria bassiana strains (CB-66 and CB-74). For Metarhizium anisopliae (E9 strain), the mean mortality started at 4th day, increasing soon after until stabilize at 8 th day. A screening of M. anisopliae isolates was done inoculating adults of the insect with 1 mL of spore suspension containing 5x108 conídia/mL (1.6x104 conídia/mm2). All isolates were pathogenic to the insect, causing mortality between 9.3 and 85.3%. The most pathogenic isolates were CB-103, CB-104, CB-233, E9 and CB-10. These 6 isolates were evaluated concerning their spore production on cooked rice. The isolates CB-104, CB-233 and CB-103 afforded the highests spores production, significantly higher compared to E9, showing potential to be used for Oryzophagus oryzae control.

Orientador: Antonio Batista Filho / Resumo: Com o objetivo de avaliar a patogenicidade e a virulência de fungos entomopatogênicos ao gorgulho aquático do arroz irrigado, Oryzophagus oryzae, foram testados 24 isolados de Metarhizium anisopliae e 2 de Beauveria bassiana. Os bioensaios foram realizados em condições controladas (26+1°C e 12 horas de fotofase). Nos testes para determinar a concentração adequada, a espécie M. anisopliae, isolado E9, apresentou maior patogenicidade quando comparado aos isolados de B. bassiana. A mortalidade confirmada, provocada pelo M. anisopliae, teve início no 4º dia, aumentando em seguida até estabilizar-se no 8º dia. Para a seleção dos isolados de M. anisopliae, adultos dos insetos foram inoculados com 1 mL de suspensão fúngica a 5x108 conídios/mL (1,6x104 conídios/mm2). Todos os isolados foram patogênicos ao inseto, sendo que a mortalidade variou entre 9,3 e 85,3 %. Os isolados de M. anisopliae mais patogênicos foram CB-103, CB-104, CB-233, E9 e CB-10. No teste de produção, os isolados CB-104, CB-233 e CB-103 foram superiores ao padrão E9, apresentando-se promissores para a utilização no controle de Oryzophagus oryzae. / Abstract: Strains of Metarhizium anisopliae and Beauveria bassiana were evaluated concerning their pathogenicity and virulence for control of the rice water weevil, Oryzophagus oryzae. Bioassay conditions were 26+1ºC and 12 h. light. M. anisopliae (E9 strain) was been more pathogenic than two Beauveria bassiana strains (CB-66 and CB-74). For Metarhizium anisopliae (E9 strain), the mean mortality started at 4th day, increasing soon after until stabilize at 8 th day. A screening of M. anisopliae isolates was done inoculating adults of the insect with 1 mL of spore suspension containing 5x108 conídia/mL (1.6x104 conídia/mm2). All isolates were pathogenic to the insect, causing mortality between 9.3 and 85.3%. The most pathogenic isolates were CB-103, CB-104, CB-233, E9 and CB-10. These 6 isolates were evaluated concerning their spore production on cooked rice. The isolates CB-104, CB-233 and CB-103 afforded the highests spores production, significantly higher compared to E9, showing potential to be used for Oryzophagus oryzae control. / Mestre

Two field trials were conducted to determine the impact of water management on the efficacy of insecticide seed treatments against rice water weevil, Lissorhoptrus oryzophilus Kuschel, in rice at the Delta Research and Extension Center during 2011 and 2012. The performance of thiamethoxam, chlorantraniliprole, and clothianidin was evaluated when the permanent flood was established at different timings (6 and 8 weeks after planting) and the effect of flush number (0, 1, or 2) on seed treatment performance was evaluated. Seed treatment efficacy was not impacted by delayed flooding, but 2 flushes reduced efficacy of some seed treatments. Experiments were also conducted to determine the impact of reduced seeding rates found in hybrid rice production on the efficacy of insecticide seed treatments targeting rice water weevil. Efficacy was similar when comparing currently labeled rates of thiamethoxam, chlorantraniliprole, and clothianidin with higher rates of these products.