Limited Mating Ability of a Wasp Strain with Rickettsia-Induced Thelytoky

Sexual reproduction is the dominant mode of reproduction in plants and animals; however, some species from various taxonomic groups reproduce asexually. Because some of these asexual species lack DNA recombination and so have low genetic variability, these asexual species are more likely to go extinct than sexual species. Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae) is a solitary endoparasitoid in which both arrhenotokous and thelytokous strains occur in sympatry. The thelytokous strain is infected by a parthenogenesis-inducing Rickettsia bacterium. We investigated whether fertilized progeny can be produced between females and antibiotic-induced males of the thelytokous strain. The males produced by antibiotic treatment showed the same courtship behaviors as the arrhenotokous males, but at a lower rate, and did not produce fertilized progeny. The results confirm that the thelytokous strain has been maintained by a functional apomixis mechanism rather than by occasional sex, preserving a degree of heterozygosity.

Population fluctuation of Phyllocnistis citrella and its parasi-toids in two citrus species in Western Crete (Greece)

Population fluctuation, percentage of parasitism and parasitoid species composition of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) were studied in a citrus orchard with orange and mandarin trees in Chania (Greece), in 1999, three years after the release of the in-troduced parasitoids Citrostichus phyllocnistoides (Narayanan), Quadrastichus sp., Semielacher petiolatus (Girault), Cirrospilus quadristriatus (Subba Rao and Ramamani) and Ageniaspis citricola Logvinovskaya. Results showed that significantly more P. citrella individuals per leaf were recorded on orange than on mandarin trees. Regarding the parasitoid complex composition, the exotic species C. phyllocnistoides, S. petiolatus and Quadrastichus sp., as well as the natives Pnigalio pectinicornis L. and Neochrysocharis formosa (Westwood) were recorded. Among them, C. phyllocnistoides was the most abundant, followed by S. petiolatus. The average percentage of parasitism reached 17% and 22% on orange and mandarin, respectively.

Studies on diversity and abundance of parasitoids of Chromatomyia horticola (Goureau) (Agromyzidae: Diptera) in north-western Himalayas, India

Pea leafminer, Chromatomyia horticola (Goureau) is an important pest of many vegetable and ornamental crops. The present investigation was carried out to study the parasitoid diversity of this pest in different agroclimatic conditions of Himachal Pradesh, India. Sixteen species of parasitoids viz. Diglyphus horticola Khan, Diglyphus isaea (Walker), Zagrammosoma sp., Pnigalio sp., Quadrastichus plaquoi Reina and LaSalle, Asecodes erxias (Walker), Closterocerus sp., Neochrysocharis formosa (Westwood), Chrysocharis sp, Chrysocharis indicus Khan, Pediobius indicus Khan (Eulophidae), Opius exiguus (Wesmael), Dacnusa sp. (Braconidae), Cyrtogaster sp., Sphegigaster sp. (Pteromalidae), and Gronotoma sp. (Figitidae) were recorded parasitizing C. horticola in different agro-climatic zones of Himachal Pradesh. Agro-climatic zone II (sub-temperate mid-hills) was the richest in parasitoid diversity (14 species) followed by zone I (11 species), zone III (7 species) and zone IV (4 species) which are characterized by sub-tropical sub-montane, wet temperate high hills and dry temperate high hills, respectively. Shannon diversity index, species richness, species evenness and species dominance varied from 0.69-1.71, 1.39-2.64, 0.50-0.71 and 0.29-0.50, respectively. D. isaea and D. horticola were the dominant parasitoids of C. horticola contributing 41.46-80.15 and 9.16-50.65 per cent of the total parasitization, respectively, in different agro climatic zones. The study highlights the role of different parasitoids in natural control of the leaf miner and will be useful for designing the IPM strategies for the pest.

Parasitoids (Hymenoptera) of leafminer flies (Diptera: Agromyzidae) from Bangladesh

The objective of this study was to determine hymenopteran parasitoids attacking leafminers (Agromyzidae: Diptera) in Bangladesh. Four parasitoid species, viz. Chrysocharis pentheus (Walker), Neochrysocharis formosa (Westwood) and Cirrospilus sp. belonging to family Eulophidae and Opius sp. under family Braconidae of the order Hymenoptera are reported as new to the fauna of Bangladesh. All parasitoids were reared from three agromyzid flies namely Liriomyza sativae Blanchard, Melanagromyza obtusa Mallochand and Ophiomyia phaseoli (Tryon).