Mating behaviour and alternative oviposition sites for male eggs in the heteronomous hyperparasitoid Coccophagus gurneyi Compere (Hymenoptera : Aphelinidae)

The aphelinid parasitoid Coccophagus gurneyi Compere has unusual sex-related host relationships. Females are diploid and develop internally within mealybugs Pseudococcus calceolariae (Maskell). Males, in contrast, are haploid and hyperparasitic, developing on primary parasitoid larvae within the mealybugs. Furthermore, males have been claimed to be capable of either internal or external development, depending on the precise site of deposition of the haploid egg. This diversity of developmental pathways could indicate the existence of a sibling-species complex. We therefore quantified the mating and ovipositional behaviour of C. gurneyi, for comparison with that of an undescribed sibling species. We also checked whether the females deposit male eggs in alternative sites. The pattern of mating was found to be typical of mating behaviour in Coccophagus spp. and was consistent among all mating pairs, suggesting that the colony comprised one species. Further, the mating behaviour was significantly different from that of the undescribed sibling species. The site of male egg deposition varied and is apparently dictated by two factors; whether the mealybug is parasitised and, if so, the size of the parasitoid it contains. If the mealybugs were unparasitised or if the parasitoids within the mealybugs were small (< 0.53 mm), male eggs were deposited within the mealybug haemocoel. If the parasitoids were large (> 1.05 mm), male eggs were deposited within the parasitoids. These results support the claim of alternate host relationships and developmental pathways within males of C. gurneyi.

Transmissão experimental do Grapevine virus B pela cochonilha Pseudococcus longispinus Targioni-Tozzetti (Hemiptera: Pseudococcidae)

Em São Paulo, existem dois isolados do Grapevine virus B (GVB), sorologicamente semelhantes e sintomatologicamente distintos, que causam a doença denominada fendilhamento cortical ("grapevine corky bark", GCB). Na literatura estrangeira existem relatos de que o GVB pode ser transmitido por cochonilhas brancas. O objetivo do presente trabalho foi o de verificar a transmissibilidade do GVB de videira infectada para videira sadia através da cochonilha da espécie Pseudococcus longispinus. Os dois isolados do vírus foram testados: o isolado comum (GVB-C) e o isolado Itália (GVB-I). A confirmação de infecção foi feita através da análise visual de sintomas, ELISA e RT-PCR. Em todos os testes de inoculação experimental, os primeiros sintomas da virose foram notados com, aproximadamente, 8 a 12 meses após a exposição às cochonilhas. Plantas sadias da variedade LN-33, mantidas ao redor de uma planta infectada com o GVB-C e altamente infestada pela P. longispinus, tornaram-se infectadas com incidência de 54,2%, após 4 anos. Empregando-se inoculação experimental com cochonilhas virulíferas, plantas da indicadora LN-33 apresentaram infecção de 46,2% e 40,0% para o GVB-C e GVB-I, respectivamente, após 3 anos de observações. Apesar desta espéciede cochonilhaocorrer de maneira eventual nos vinhedos do Estado de São Paulo, precauções devem ser tomadas em áreas onde são mantidos clones sadios de variedades de copa e de porta-enxerto de videira, visto que esses insetos, além de possuírem grande número de plantas hospedeiras, também podem transmitir outros importantes vírus da videira.

Dinâmica de populações e preferência alimentar da cochonilha-da-raiz (Pseudococcus comstocki) pela tiririca

A flutuação populacional da cochonilha-da-raiz (Pseudococcus comstocki) (Kuwana, 1902) e sua preferência alimentar foram estudadas quando infestando plantas de tiririca (Cyperus rotundus) oriundas dos municípios de Lavras, Lambari e Três Pontas, localizados na região sul do Estado de Minas Gerais, no período de março de 1996 a março de 1997. A cochonilha-da-raiz infestou a tiririca durante todos os meses de avaliação, variando, entretanto, a intensidade de infestação. Entre os locais estudados, Lambari apresentou a mais baixa densidade populacional da praga; em Lavras e Três Pontas as infestações foram semelhantes, sendo as mais elevadas. A temperatura e a umidade relativa do ar foram as variáveis climáticas que mais influenciaram a flutuação populacional da cochonilha-da-raiz em plantas de tiririca, nas três localidades estudadas. Foi observada maior preferência alimentar das cochonilhas por plantas de tiririca oriundas de Lavras e Três Pontas.

Efeito da temperatura no desenvolvimento e sobrevivência da cochonilha pseudococcus longispinus (Targioni Tozzetti, 1867) (hemiptera: Pseudococcidae) em cafeeiro

The longtailed mealybug Pseudococcus longispinus (Targioni Tozzetti, 1867) (Hemiptera: Pseudococcidae) has been reported attacking coffee crops causing fruit fall in the State of Minas Gerais, Brazil. The knowledge of the population dynamic of this pest is then necessary to implement control measures. Its development was studied at temperatures of 15, 20, 25, 30 and 35°C, determining the thermal requirements. The insects were confined inside a Petri dish containing a foliar disc of 4 cm diameter of Coffea arabica L., cultivar 'Acaiá Cerrado'. The temperature affected the P. longispinus development and survival. Few insects survived at temperatures of 15 and 30°C, and 100% of mortality was obtained at 35°C. The duration of the nymphal stage was reduced when the temperature was increased from 20 to 25°C, with a survival rate of 80% at both temperatures. The thermal parameters varied according to the development stage of the mealybug and the base temperature was fixed at 8.0 °C for the nymphal stage of females, a thermal constant of 422.1 day degrees and number of generations increased with rising temperature. The optimal temperature for the insect development was 25°C.

A survey of mealybugs infesting South-Brazilian wine vineyards

ABSTRACTMealybugs (Hemiptera: Pseudococcidae) are important pests of the grapevine Vitis spp. and are responsible for direct and indirect damage to production. The main mealybug species present in wine grapevine (Vitis vinifera L.) in Southern Brazil were identified and their incidence evaluated. Bunch-samples (n = 50) from 131 vineyards located in the Serra Gaúcha Region (RS) of Brazil were analyzed at harvest, and the occurrence of mealybugs in the roots was evaluated at the time of eradication of plants for replanting. Mealybugs were reared in laboratory until adulthood for species determination. The species Dysmicoccus brevipes (Cockerell, 1983), Dysmicoccus sp., Planococcus citri (Risso, 1813), Pl. minor(Maskell, 1897), Pseudococcus viburni (Signoret, 1875) and Pseudococcus sp. were identified in bunches. Dysmicoccus sp., D. umbambae Granara de Willink, 2009, Pl. citri and Pseudococcus sp. were found in the roots. Pl. citri (31.4%) and Dysmicoccus sp. (22.7%) were the most common species found in wine grape bunches in the Serra Gaúcha Region.

Cacao swollen shoot virus in Nigeria: analysis of a pathogen and its vectors

Cacao swollen shoot virus (CSSV) causes the Cacao swollen shoot virus disease (CSSVD) and significantly reduces production in West African cacao. This study characterised the current status of the disease in the major cacao growing States in Nigeria and attempted a clarification on the manner of CSSV transmission. Two separate field surveys and sample collections were conducted in Nigeria in summer 2012 and spring 2013. PCR-based screening of cacao leaf samples and subsequent DNA sequencing showed that the disease continues to persist in Ondo and Oyo States and in new cacao sites in Abia, Akwa Ibom, Cross River and Edo States. Mealybug samples collected were identified using a robust approach involving environmental scanning electron microscopy, histology and DNA barcoding, which highlighted the importance of integrative taxonomy in the study. The results show that the genus Planococcus (Planococcus citri (Risso) and/or Planococcus minor (Maskell)) was the most abundant vector (73.5%) at the sites examined followed by Formicococcus njalensis (Laing) (19.0 %). In a laboratory study, the feeding behaviour of Pl. citri, Pseudococcus longispinus (Targioni-Tozzetti) and Pseudococcus viburni (Signoret) on cacao were investigated using electrical penetration graph (EPG) analysis. EPG waveforms reflecting intercellular stylet penetration (C), extracellular salivation (E1e), salivation in sieve elements (E1), phloem ingestion (E2), derailed stylet mechanics (F), xylem ingestion (G) and non-probing phase (Np) were analysed. Individual mealybugs exhibited marked variation within species and significantly differed (p ≤ .05) between species for E1e and E1. PCR-based assessments of the retention time for CSSV in viruliferous Pl. citri, Ps. longispinus and Ps. viburni fed on a non-cacao diet showed that CSSV was still detectable after 144 hours. These unusually long durations for a pathogen currently classified as a semi-persistent virus have implications for the design of non-malvaceous barrier crops currently being considered for the protection of new cacao plantings.

Estudo diagnóstico e taxonômico de cochonilhas (Hemiptera: Coccoidea) associadas às plantas cítricas no estado de Sâo Paulo, Brasil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A problemática das cochonilhas-algodão em cultura protegida de hortícolas na Região Oeste

Mestrado em Engenharia Agronómica - Horto-fruticultura e Viticultura - Instituto Superior de Agronomia - UL

Multiplex PCR para a identificação de cochonilhas farinhentas (Hemiptera Pseudococcidae) presentes na cultura da videira no Brasil.

Uma alta diversidade de espécies de cochonilhas farinhentas (Hemiptera:Pseudococcidae) tem sido observada na cultura da videira. Algumas espécies são inclusive consideradas pragas quarentenárias para outros países. A identificação de cochonilhas farinhentas é um dos fatores limitantes para o manejo destes insetos no campo, em decorrência da grande similaridade morfológica observada entre espécies próximas e da variação morfológica que ocorre em alguns grupos em decorrência do hospedeiro e da temperatura de desenvolvimento. Além disto, a identificação destes insetos baseia-se em características morfológicas presentes apenas em fêmeas adultas, realizada por poucos especialistas. O objetivo deste trabalho foi desenvolver um ?kit? de identificação molecular das principais espécies de cochonilhas farinhentas presentes na cultura da videira no Brasil [(Dysmicoccus brevipes (Cockerell), Phenacoccus solenopsis (Tinsley), Planococcus citri (Risso), Planococcus ficus (Signoret) e Pseudococcus viburni (Signoret)]. Cochonilhas farinhentas foram coletadas na Serra Gaúcha, RS, Vale do São Francisco (Polos Juazeiro- BA e Petrolina-PE) e em cidades produtoras de uvas do Paraná.