Samy Sayed

Diversity and evolution of the Cydia pomonella granulovirus

Eight new field isolates of Cydia pomonella granulovirus (CpGV) originating in Iran and Georgia and one English CpGV isolate were analysed for restriction fragment length polymorphisms (RFLPs) and by partial genome amplification and sequencing. According to the observed RFLPs, most of the predominant genotypes of these isolates could be assigned to those present in previously found isolates originating from Mexico (CpGV-M), England (CpGV-E) and Russia (CpGV-R). We suggest that these isolates should be designated genome A, B and C types, respectively. A fourth genome type was identified in three isolates and is designated D type. The isolates with A, B and D type genomes contained four open reading frames (ORFs) (ORF63-ORF66) not present in C type genomes. The lack of these ORFs in other granuloviruses suggests that the C type genome is evolutionarily ancestral to the other genome types. The B and D type genomes contained an additional insertion of a non-protein coding region of 0.7 kb, which was at different genome locations. Analysis of the partial gene sequences of late expression factor 8 (lef-8), lef-9 and polyhedrin/granulin (polh/gran) genes revealed single nucleotide polymorphisms (SNPs) that corresponded to the RFLP types. Phylogenetic analyses based on these SNPs corroborated the proposed ancestry of the C type genome. C type viruses were also less virulent to neonate codling moth larvae than the other virus types. In conclusion, the known diversity of CpGV isolates can be described by four major genome types, which appear to exist in different isolates as genotype mixtures.

Preliminary molecular identification of a predatory bug, Orius albidipennis, collected from ornamental plants

Abstract Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) is a generalist predator used for biological control of insects attacking ornamental plants. Molecular identification of this species using internal transcribed spacer 1 (ITS1) of ribosomal DNA was conducted for the first time. The complete sequence of ITS1 and fragments of its flanking 18S and 5.8S rDNA genes are reported herein. The estimated length of ITS1 of O. albidipennis was 305 bp. This spacer was nearly identical to its counterpart of Orius sp-Taif strain in spite of the difference in their length. The phylogentic relationships were determined using the maximum-likelihood method supported with strong bootstrap probabilities clustering of both taxa together. Further molecular markers could be useful to identify the Taif strain and support its sister relationship to the Egyptian O. albidipennis.

Molecular variability of Chrysoperla Steinmann, 1964 (Neuroptera: Chrysopidae) inhabiting western Saudi Arabia

Abstract. The large ribosomal RNA subunit (16S rRNA) and cytochrome C subunit 3 (CO3) genes have been partially amplified and sequenced for the species of Chrysoperla Steinmann, 1964 (Neuroptera: Chrysopidae) inhabiting the western part of Saudi Arabia to examine their molecular variability. Insect samples were collected from three distant localities, which were Tabouk in the north, Jeddah in the middle and Jazan in the south of the country. The concatenated sequences (904 bp) have been manipulated by three analytical methods (maximum-parsimony, neighbor-joining and maximum-likelihood) producing one fixed tree. The tree topology divided, with strong statistical supports, Saudi Arabian Chrysoperla into two clusters. Jeddah and Tabouk samples clustered (BP = 100%) with both Chrysoperla carnea (Stephens, 1836) and Chrysoperla nipponensis (Okamoto, 1914), while Jazan samples grouped (BP = 100%) with Dichochrysa tacta (Navás, 1921). Both pairwise genetic distances obtained from the concatenated data and amino acid substitution in CO3 gene supported this division. It could be concluded that Saudi Arabian Chrysoperla constitutes a species complex and requires further molecular investigation.

Suitability of four different prey species for Dichochrysa tacta (Neuroptera: Chrysopidae)

ABSTRACT The prey suitability for generalist insect predators is an important factor in efficient mass rearing. This work constitutes the first biological study of the predatory lacewing Dichochrysa tacta. We tested the effects of four different prey species on the biological parameters of the predatory lacewing D. tacta under laboratory conditions. These prey species consisted of Ephestia kuehniella (Zeller) and the aphids: Aphis fabae, Aphis punicae and Macrosiphum rosae. The results showed that prey species elicited a significant effect on preimaginal development times, survival, adult longevity and fecundity. In contrast, the progeny sex ratio, egg hatch and egg duration were not significantly affected by prey species. Eggs of E. kuehniella were the most suitable prey among those tested, and led to high survival rates, short development times for the preimaginal stages, long adult longevity, high fecundity, highest intrinsic rate of increase (rm) and highest net reproductive rate (R0) of D. tacta. Nymphs of both A. punicae and M. rosae were also relatively favourable prey, whereas nymphs of A. fabae were less suitable and resulted in reduced development, survival, adult longevity, fecundity, rm and R0. These results could be useful for optimising the mass rearing of D. tacta as an indigenous predator and for understanding its population dynamics in relation to different prey species in the field.

Tropical grasshopper glutathione-S-transferase and detoxification of plant allelochemicals in Calotropis procera

Poecilocerus bufonius inhabits Saudi Arabia and uses Calotropis procera as its main host plant. Cardenolids of this plant are used by this grasshopper as chemical defence against the natural enemies. The activity of enzyme detoxification in mid-gut wall for these allelochemicals has been determined in this study. Results indicate that the activity of glutathione-S-transferase (GST) was significantly higher after 24 hours of feeding on the main host plant but no difference has been found after one, two, four and five hours of feeding.