A Survey of Scale Insects (Sternorryncha: Coccoidea) Occurring on Table Grapes in South Africa

Increasing international trade and tourism have led to an increase in the introduction of exotic pests that pose a considerable economic threat to the agro-ecosystems of importing countries. Scale insects (Sternorryncha: Coccoidea) may be contaminants of export consignments from the South African deciduous fruit industry to the European Union, Israel, United Kingdom and the United States, for example. Infestations of immature scale insects found on South African fruit destined for export have resulted in increasing rates of rejection of such consignments. To identify the risk posed by scale insect species listed as phytosanitary pests on table grapes to the abovementioned importing countries, a field survey was undertaken in 2004–2005 in vineyards throughout all grape-producing regions in South Africa. Coccoidea species found during the current field survey were Planococcus ficus (Signoret), Pseudococcus longispinus (Targioni Tozzetti), Coccus hesperidum L. and Nipaecoccus viridis (Newstead). With the exception of Pl. ficus, which has only been collected from Vitis vinifera (Vitaceae) and Ficus carica (Moraceae) in South Africa, these species are polyphagous and have a wide host range. None of the scale insect species found to occur in vineyards in South Africa pose a phytosanitary risk to countries where fruit are exported except for Ferrisia malvastra (McDaniel) and N. viridis that have not been recorded in the USA. All scale insects previously found in vineyards in South Africa are listed and their phytosanitary status discussed. The results of the survey show that the risk of exporting scale insect pests of phytosanitary importance on table grapes from South Africa is limited

Preliminary studies on two Diaspididae (Hemiptera) species feeding on Johnsongrass (Sorghum halepense) in Turkey

The scale insects Acanthomytilus sacchari (Hall) and Duplachionaspis erianthi Borchsenius (Hemiptera, Diaspididae) are newly recorded as indigenous insects from Turkey. Both A. sacchari and D. erianthi were found to feed only on rhizomes of Johnsongrass. A field study was conducted to determine host ranges and feeding effects of these scale insects on Johnsongrass, Sorghum halepense (L.) Pers. No feeding of these species was observed on Zea mays L. (maize), Sorghum sudanense Staph. (sorghum), Aegilops triuncialis L. (barbed goatgrass), Avena fatua L. (wild oat), A. sterilis (sterile oat), Bromus tectorum L. (downy brome), Cynodon dactylon (L.) Pers. (bermudagrass), Phragmites australis (Cav.) Trin. ex Steudel (common reed), Poa bulbosa L. (bulbous bluegrass), or Secale montanum Guss. (wild rye). The mean infestation rates of the scale insects on Johnsongrass in southeastern Anatolia were 11.47% and 1.64% for A. sacchari and D. erianthi, respectively. Further investigations are required to clarify their biology and damage to Johnsongrass under field conditions.The scale insects Acanthomytilus sacchari (Hall) and Duplachionaspis erianthi Borchsenius (Hemiptera, Diaspididae) are newly recorded as indigenous insects from Turkey. Both A. sacchari and D. erianthi were found to feed only on rhizomes of Johnsongrass. A field study was conducted to determine host ranges and feeding effects of these scale insects on Johnsongrass, Sorghum halepense (L.) Pers. No feeding of these species was observed on Zea mays L. (maize), Sorghum sudanense Staph. (sorghum), Aegilops triuncialis L. (barbed goatgrass), Avena fatua L. (wild oat), A. sterilis (sterile oat), Bromus tectorum L. (downy brome), Cynodon dactylon (L.) Pers. (bermudagrass), Phragmites australis (Cav.) Trin. ex Steudel (common reed), Poa bulbosa L. (bulbous bluegrass), or Secale montanum Guss. (wild rye). The mean infestation rates of the scale insects on Johnsongrass in southeastern Anatolia were 11.47% and 1.64% for A. sacchari and D. erianthi, respectively. Further investigations are required to clarify their biology and damage to Johnsongrass under field conditions.</p

Molecular chaperones and the assembly of the prion Sup35p, an in vitro study

The protein Sup35 from Saccharomyces cerevisiae possesses prion properties. In vivo, a high molecular weight form of Sup35p is associated to the [PSI(+)] factor. The continued propagation of [PSI(+)] is highly dependent on the expression levels of molecular chaperones from the Hsp100, 70 and 40 families; however, so far, their role in this process is unclear. We have developed a reproducible in vitro system to study the effects of molecular chaperones on the assembly of full-length Sup35p. We show that Hsp104p greatly stimulates the assembly of Sup35p into fibrils, whereas Ydj1p has inhibitory effect. Hsp82p, Ssa1p and Sis1p, individually, do not affect assembly. In contrast, Ssa1p together with either of its Hsp40 cochaperones blocks Sup35p polymerization. Furthermore, Ssa1p and Ydj1p or Sis1p can counteract the stimulatory activity of Hsp104p, by forming complexes with Sup35p oligomers, in an ATP-dependent manner. Our observations reveal the functional differences between Hsp104p and the Hsp70–40 systems in the assembly of Sup35p into fibrils and bring new insight into the mechanism by which molecular chaperones influence the propagation of [PSI(+)]

J-protein co-chaperone Sis1 required for generation of [RNQ+] seeds necessary for prion propagation

Yeast prions are protein-based genetic elements capable of self-perpetuation. One such prion, [RNQ+], requires the J-protein Sis1, an Ssa Hsp70 co-chaperone, as well as the AAA+ ATPase, Hsp104, for its propagation. We report that, upon depletion of Sis1, as well as upon inactivation of Hsp104, Rnq1 aggregates increased in size. Subsequently, cells having large aggregates, as well as an apparently soluble pool of Rnq1, became predominant in the cell population. Newly synthesized Rnq1 localized to both aggregates and bulk cytosol, suggesting that nascent Rnq1 partitioned into pools of prion and nonprion conformations, and implying that these large aggregates were still active as seeds. Ultimately, soluble Rnq1 predominated, and the prion was lost from the population. Our data suggest a model in which J-protein:Hsp70 machinery functions in prion propagation, in conjunction with Hsp104. Together, these chaperones facilitate fragmentation of prion polymers, generating a sufficient number of seeds to allow efficient conversion of newly synthesized Rnq1 into the prion conformation