Morphological features,development and reproduction of Melittobia acasta on Bombus terrestris

Morphological features, development and reproduction behavior of the parasite Melittobia acasta (Walker) were studied when reared on the pupae of the bumblebee Bombus terrestris L. in the laboratory under 23°C, 50% relative humidity and 12 h light : 12 h dark conditions. The parasites laid transparent white and elongated eggs. Newly hatched larval size and shape were very similar to eggs but they were identified by their body segments. Larvae increased their body size through moulting and transformed into a vermiform shape. Male pupae were shiny brown with dots. The female pupae were distinguished by their black shiny color, shorter size and the presence of compound eyes. Adult male pupae were dark brown and dwarf‐winged, whereas female pupae were macropterous and brachypterous. Reproduction took place by fertilization and also parthenogenetically. Mean fecundity within 5 days by mated (47.9 ± 30.5 female^?1) and virgin (7.4 ± 6.8 female^?1) females were statistically different. Mated females laid fertilized eggs that produced adult males or females, whereas virgin females laid unfertilized eggs that produced males. Development durations of the virgin female originated eggs, larvae, pupae and adults were statistically identical with those of mated females. The parasites were female‐biased and foundress number did not affect offspring sex ratio. This study shows that both mated and virgin females of M. acasta can produce many offspring on B. terrestris pupae within a short period, indicating that they are dangerous parasites of the bumblebee in a mass rearing system.     

Taxonomic Review of the Genus Eudorylas Aczél (Diptera: Pipunculidae) in Korea

The Korean species of the genus Eudorylas Aczél have been studied. A total of 16 species are arranged herein. Among them, E. paraappendiculatus sp. nov. is new to science, and E. nomurai Morakote et Yano, 1990 is newly recorded in the Korean fauna.     

Turtle Lung Cells Produce a Melanization-Stimulating Activity That Promotes Melanocytic Differentiation of Avian Neural Crest Cells

We found previously that neural crest cells in turtle embryos migrated into the lung buds and melanocytes were located in the lungs. The finding suggested to us that the lungs provide a stimulatory factor(s) to the differentiation of neural crest cells into melanocytes. We have established lung cell lines to facilitate analysis of the interactions of neural crest cells with the environment in melanocyte development. One cell line, TLC-2, was found to produce a putative melanization-stimulating activity (MSA), which promoted the melanocyte differentiation in vitro of avian neural crest cells. The TLC-2-derived MSA was different from that of basic fibroblast growth factor (bFGF), α-melanocyte stimulating hormone (α-MSH), and steel factor (SLF). Its molecular weight was estimated to be within the range of 150 kD. Our findings suggest that MSA may be a novel factor exercising a positive control over melanocyte differentiation.     

Fidelity of Hymenoptera and Diptera pollinators in onion (Allium cepa L.) pollination

Onion (Allium cepa L.) is protandrous in nature and requires cross‐pollination to avoid inbreeding. The pollination potential of native bees (Hymenoptera) and true flies (Diptera) was assessed in the perspective of finding the best pollinators for onion cross‐pollination and seed multiplication. The community of pollinators was composed of four bee species and twelve true fly species. Episyrphus balteatus, Eupeodes sp., Musca domestica and Eristalinus aeneus were the most abundant pollinators. The maximum pollinator activity was observed from 12 to 24 days after opening of the flowers. The pollination effectiveness of tested bees (Apis dorsata and Apis florea) was greater than true flies (E. balteatus, Eupeodes sp., M. domestica, E. aeneus and Callihoridae sp.) in terms of Spears values.     

APPLICATION OF A TRANSPOSON FOOTPRINTING TECHNIQUE FOR RAPID IDENTIFICATION OF SALMONELLA TYPHIMURIUM TN5 MUTANTS REQUIRED FOR SURVIVAL UNDER DESICCATION STRESS CONDITIONS

Salmonella spp. are one of the foodborne pathogens that can be isolated in the environments of poultry houses and desiccation is a potential stress condition that can influence the survival of Salmonella spp. in this environment. In order to investigate the desiccation survival mechanism of Salmonella spp. the genome of S. typhimurium ATCC 14028 was screened for the genes potentially required for survival during desiccation using a novel method based on Tn5 mutagenesis previously developed in our laboratory. This method, termed transposon footprinting, simultaneously amplifies the Tn5-flanking sequences in a complex pool of the Tn5 mutants. As the length of the amplified DNA fragment should be unique for each distinct Tn5 mutant, the polymerase chain reaction (PCR) products separated on an agarose gel generate transposon footprints with each band in the footprint representing the corresponding Tn5 mutant. By comparing the transposon footprints from the pools of S. typhimurium Tn5 mutants before and after exposure to desiccation, Tn5 mutants that were not recovered after the selection were rapidly identified that would be easily isolated for further genetic analysis.     

Taxonomy of Tabanus cordiger Species Group (Diptera: Tabanidae) in Korea

ABSTRACT Horseflies of the Tabanus cordiger species group from Korea is revised taxonomically. A total of four species are arranged herein: T. divulsus sp. nov., T. fulvimedioides, T. kinoshitai and T. loukashkini. A key to discriminate species, annotated check lists of domestic records, and collection data for each species are provided.     

Aptness of Beauveria bassiana and enhanced diatomaceous earth (DEBBM) for control of Rhyzopertha dominica F.

A diatomaceous earth formulation enhanced with bitterbarkomycin (DEBBM) combined with Beauveria bassiana (Balsamo) Vuillemin was evaluated against lesser grain borer Rhyzopertha dominica F. (Coleoptera: Bostrychidae) under laboratory conditions. DEBBM was applied at the rates of 15 and 30 ppm alone as well as in combination with 6.69 × 10⁶, 6.69 × 10⁸ and 6.69 × 10¹⁰ conidia/kg of wheat. Mortality of treated adults was recorded after 5, 10 and 15 days of exposure. Bioassays were carried out at 20, 25 and 30°C with 55 and 75% relative humidity. The emergence of progeny was also assessed 60 days post exposure. The combined use of DEBBM and B. bassiana considerably increased adult mortality especially at increasing temperatures and longer exposure intervals compared with DEBBM and B. bassiana alone. Progeny production was less in wheat treated with high dose rates of DEBBM +B. bassiana. The per cent mycosis in the cadavers was maximum where B. bassiana was applied at low dose rates. The results of the present study indicated that a combination of DEBBM and B. bassiana may provide effective control of R. dominica.     

Effect of modified meridic diet on the development and growth of tomato fruitworm Helicoverpa armigera (Lepidoptera: Noctuidae)

The efficacy of one new modified and two old meridic diets on Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) for rearing six successive generations was studied. Duration of larval development for insects fed on the modified diet was considerably shortened as most of them went through only five stadia before pupation, while the per cent pupation and per cent eclosion were relatively higher than on other diets. The lowest pupal mortality (6.33 ± 0.13%) was recorded in the F₁ generation reared on the modified diet, whereas the highest pupal mortality (19.49 ± 0.15%) was observed in insects reared on a natural diet in the F₆ generation. Blending of chickpea Cicer arietinum L. and red kidney bean Phaseolus vulgaris L. flours with tomato paste proved highly favorable for adult reproduction. These results suggest that the vitality of the tomato fruitworm did not decline obviously after rearing on a modified diet for several generations.     

Comparative efficacy of different pesticides against mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Scolytidae)

Hypocryphalus mangiferae Stebbing is one of the most destructive insect pests of mango trees and is found to be associated with the transmission of causal organisms of mango sudden death disease. The present study was carried out to evaluate the toxicity of deltamethrin, bifenthrin, chlorpyrifos, emamectin benzoate, imidacloprid and spinosad in laboratory and field trials. Bioassay results showed that the toxicity of chlorpyrifos was significantly higher than deltamethrin but similar to bifenthrin. Deltamethrin and bifenthrin toxicity, however, increased significantly (P < 0.01) from day 1 to day 3. Spinosad was the least toxic compound while emamectin was the most toxic among new chemical insecticides tested, but its toxicity increased significantly from day 1 to day 5. Comparison of the efficacies of the insecticides using lethal times to produce 50% mortality (LT₅₀) and 90% mortality (LT₉₀) showed that the relative potencies of chlorpyrifos, emamectin, imidacloprid and spinosad were greater than bifenthrin and deltamethrin. The results of field trials showed the highest number of beetles emerged from the control twigs while significantly fewer beetles emerged from the twigs treated with bifenthrin (P < 0.05), which accounted for 12% for bifenthrin compared to that of the control. The present study demonstrated increased toxicities of systemic insecticides and chlorpyrifos compared to toxicities of deltamethrin and bifenthrin, suggesting these insecticides could be an alternative tool in a comprehensive H. mangiferae management program to eradicate the beetles from mango orchards.     

The Effect of Changes in Organic Nitrogen Concentration of Rumex obtusifolius L. on the Population Dynamics of Aphis rumicis L. (Homoptera: Aphididae)

ABSTRACT The study of plant-herbivore dynamics was carried out using Aphis rumicis L. The insect is oligophagous to the genus Rumex. It utilizes its food plant by means of phloem sucking. Here, in this study, organic nitrogen as a form of a pellet fertilizer was used as a limiting factor. The major aim of the study is to find out the tripartite relationship among soil nitrogen concentration, the plant, and the insect. Observations were made from both the natural habitat site and the manipulated field site. The result shows that Aphis rumicis responded positively to increased N concentration of leaves (p< 0.005). The application of organic nitrogen did not alter the pattern of the population dynamics of Aphis rumicis over the study period. However, it may determine the time for the optimal exploitation of resources by the insect. It is also suggested that the growth efficiency of the insect relates to the C: N ratio in the phloem.