Mealybugs (Planococcus citri) and thrips (Scirtothrips aurantii) are common and extremely damaging citrus crop pests which have proven difficult to control via conventional methods, such as chemical pesticides and insect growth regulators. The objective of this study was to determine the efficacy of entomopathogenic fungi against these pests in laboratory bioassays. Isolates of Metarhizium anisopliae and Beauveria bassiana from citrus orchards in the Eastern Cape, South Africa were maintained on Sabouraud Dextrose 4% Agar supplemented with Dodine, chloramphenicol and rifampicin at 25°C. Infectivity of the fungal isolates was initially assessed using 5th instar false codling moth, Thaumatotibia leucotreta, larvae. Mealybug bioassays were performed in 24 well plates using 1 x 107 ml-1 conidial suspensions and kept at 26°C for 5 days with a photoperiod of 12 L:12 D. A Beauveria commercial product and an un-inoculated control were also screened for comparison. Isolates GAR 17 B3 (B. bassiana) and FCM AR 23 B3 (M. anisopliae) both resulted in 67.5% mealybug crawler mortality and GB AR 23 13 3 (B. bassiana) resulted in 64% crawler mortality. These 3 isolates were further tested in dose-dependent assays. Probit analyses were conducted on the dose-dependent assays data using PROBAN to determine LC₅₀ values. For both the mealybug adult and crawlers FCM AR 23 B3 required the lowest concentration to achieve LC₅₀ at 4.96 x 10⁶ conidia ml-1 and 5.29 x 10⁵ conidia ml-1, respectively. Bioassays on adult thrips were conducted in munger cells with leaf buds inoculated with the conidial suspensions. Isolate GAR 17 B3 had the highest mortality rate at 70% on thrips while FCM AR 23 B3 resulted in 60% mortality. Identification of the isolates, FCM AR 23 B3, GAR 17 B3 and GB AR 23 13 3, were confirmed to be correct using both microscopic and molecularly techniques. ITS sequences were compared to other sequences from GenBank and confirmed phylogenetically using MEGA6. Mealybug infection was investigated using scanning electron microscopy, mycosis was confirmed but the infection process could not be followed due to the extensive waxy cuticle. These results indicate that there is potential for the isolates FCM AR 23 B3 and GAR 17 B3 to be developed as biological control agents for the control of citrus mealybug and thrips. Further research would be required to determine their ability to perform under field conditions.

Made available in DSpace on 2014-08-20T14:07:35Z (GMT). No. of bitstreams: 1 Tese_Wilson_Morandi_Filho.pdf: 463965 bytes, checksum: 4f011d565e10b13a07b93ccabfb80913 (MD5) Previous issue date: 2008-04-24 / Mealybugs of the Pseudococcidae family have been reported as causing direct damage (losses in production) and indirect (transmission of virus) in vineyards. Few information is available about the species occuring in the vineyards and the bioecology of pseudococidae in Brazil. In this work we identified the species of Pseudococcidae associated with vineyards in Serra Gaúcha region; studied the biology and determined the thermal requirements of Planococcus citri estimating the number of annual generations in different producing regions and, evaluated the effect of insecticides alternative to phosphorous for the control of the species. P. citri, Planococcus minor, Pseudococcus viburni, Pseudococcus maritimus, Dysmicoccus brevipes were found associated with the vineyards in the region. P. citri was the most abundant species. The biology of P. citri was studied in leaves of the vine cultivars Cabernet Sauvignon, Italy and Isabel, in fruits of cultivar Italy, in roots of cultivars Isabel and in 101-14 and IAC-572 rootstocks. On roots of the rootstock IAC-572, P. citri was unable to complete the life cycle. The average period from egg to adult males was 24.63 ± 0.10 days with viability of 32% while females lasted 32.00 ± 0.11 days with viability of 56% when fed on leaves of vine cultivars. In roots, the cycle duration of the females and males was 32.45±0.19 and 29.50±0.51 days, respectively. The lowest viability of the nymphal cycle was found in roots of Isabel, 8.1% for females and 4.0% for males while the high viability was obtained in leaves of Cabernet Sauvignon, 62.7% and 32.7% for females and males, respectively. The mealybug P. citri completed the life cycle in leaves of the vine cultivars Cabernet Sauvignon, Italy, Isabel; roots of the rootstocks 101-14 and Isabel. The Italy grape berries allowed the nymphal development of P. citri, however the adults were infertile. The roots of the door graft IAC-572 are immune to P. citri. The speed of development of P. citri increases with temperature elevation. The temperatures of 25°C and 28°C were the most appropriate for the insect development. The threshold temperature and thermal constant for the full cycle (egg-adult) of P. citri in vine leaves of the cultivar Italy was 8.16°C and 574.71 degree days, respectively. Based on the thermal requirements, we estimated that the insect may have 5.7 annual generations in Bento Gonçalves (RS), 6.2 in Bagé (RS), 6.9 in São Lourenço (MG), 7.9 in Londrina ( PR), 9.7 in Jales (SP) and 11.5 in Petrolina (PE). In the assessment of insecticides for the control of the insect, the neonicotinoids acetamiprid (0.60 g ai / plant), imidacloprid (0.70 g ai / plant) and thiamethoxam (0.75 g ai plant) were effective in the control of P. citri in vine plants with 1 year old. In adult plants (15 years) the same treatments and doses were not effective to pest control. Foliar spray of acetamiprid (6 20 ia/100L), imidacloprid (7 ia/100L), thiamethoxam (7.5 g ia/100L) and insect growth regulators buprofezin (25 ia/100L) and pyriproxyfen (10g ai 100L) were not effective to control P. citri. / Cochonilhas da família Pseudococcidae têm sido relatadas como causadoras de danos diretos (perdas na produção) e indiretos (transmissão de vírus) na cultura da videira. Poucas informações estão disponíveis sobre as espécies presentes nos vinhedos e a bioecologia das mesmas. Neste trabalho foram identificadas as espécies de Pseudococcidae associados à cultura da videira na região da Serra Gaúcha; estudado a biologia e determinado as exigências térmicas de Planococcus citri, estimado o número de gerações anuais nas diferentes regiões produtoras e avaliado o efeito de inseticidas alternativos aos fosforados para o controle da espécie. P. citri, Planococcus minor, Pseudococcus viburni, Pseudococcus maritimus, Dysmicoccus brevipes foram constatadas associadas à cultura da videira na região da Serra Gaúcha, sendo que P. citri foi a espécie mais abundante nos vinhedos. A biologia de P. citri foi estudada em folhas de videira das cultivares Cabernet Sauvignon, Itália e Isabel, bagas da cultivar Itália e raízes da cultivar Isabel e porta-enxertos 101-14 e IAC-572. Em raízes do porta-enxerto IAC-572 a cochonilha não completou o ciclo biológico. Em bagas de uva Itália, o inseto completou a fase de ninfa, porém os adultos foram inférteis. Em folhas de videira das diferentes cultivares, a duração média do período ovo a adulto dos machos foi de 24,630,10 dias com viabilidade de 32% enquanto que as fêmeas duraram 32,000,11 dias com viabilidade de 56%. Em raízes, a duração do ciclo biológico das fêmeas e machos foi de 32,450,19 e 29,500,51 dias, respectivamente. A menor viabilidade do ciclo ninfal foi verificada em raízes de Isabel, sendo de 8,1% para fêmeas e 4,0% para machos enquanto a maior foi obtida em folhas de Cabernet Sauvignon, sendo de 62,70% e 32,7% para fêmeas e machos, respectivamente. Em folhas a fecundidade foi de 67,2710,70; 53,331,68 e 66,094,68 ovos por fêmea nas cultivares Cabernet Sauvignon, Itália e Isabel, respectivamente. Enquanto em raízes, foi obtido 30,406,12 e 70,0010,5 ovos por fêmea no porta-enxerto 101-14 e Isabel, respectivamente. A velocidade de desenvolvimento de P. citri aumenta com a elevação da temperatura sendo a faixa de temperatura entre 25 ºC e 28 ºC a mais adequada para a espécie. A temperatura base e a constante térmica para o ciclo total (ovo-adulto) de P. citri em folhas de videira da cultivar Itália foi de 8,16 ºC e 574,71 graus-dia, respectivamente. Com base nas exigências térmicas estimou-se que o inseto pode completar 5,7 gerações anuais em Bento Gonçalves (RS), 6,2 em Bagé (RS), 6,9 em São Lourenço (MG), 7,9 em Londrina (PR), 9,7 em Jales (SP) e 11,5 em Petrolina (PE). Na avaliação de inseticidas para o controle de P. citri verificou-se que os neonicotinóides acetamiprid (0,60g i.a./planta), imidacloprid (0,70g i.a./planta) e tiametoxam (0,75g i.a./planta) são eficazes no controle de P. citri em plantas de videira com um ano de idade. Entretanto, em plantas com 15 anos de idade de C. sauvignon os inseticidas neonicotinóides acetamiprid, imidacloprid e tiametoxam nas mesmas doses não foram eficazes para o controle da espécie. Ao estudar o efeito dos inseticidas neonicotinóides acetamiprid (6g i.a./100L), imidacloprid (7g i.a./100L), tiametoxam (7,5g i.a./100L) e os reguladores de crescimento buprofezin (25g i.a./100L) e pyriproxyfen (10g i.a./100L) aplicados via foliar observou-se que os mesmos não proporcionam mortalidade significativa de P. citri na cultura da videira após a pulverização nos vinhedos e avaliação da mortalidade em laboratório.