The inhibition of molting fluid enzymes of Pod borer,Helicoverpa armigera (Hubner) by an aspartic protease inhibitor: Its effects on insect development

In this study, the inhibition of molting fluid enzymes from Helicoverpa armigera by an aspartic protease inhibitor, Alkalophilic Thermophilic Bacillus Inhibitor (ATBI) purified from Bacillus sp. is reported. The in vitro experiments showed 80% inhibition (IC₅₀= 48 µM) of hemoglobin hydrolyzing and 95% inhibition (IC₅₀= 35 µM) of chitin hydrolyzing activity from molting fluid by ATBI (IC₅₀ value is the ATBI concentration for 50% inhibition of total enzymatic activity). The treatment of H. armigera larvae with 400 µM ATBI recorded 20% larval mortality, 27.77% deformed pupae and 12.22% deformed adults. The LC₅₀ value (Concentration of ATBI calculated to give 50% mortality) calculated for insect population was found to be 330.06 µM. Similarly, significant variations in mean larval and pupal weight, no. of eggs laid per female and percent hatching of eggs were observed at higher concentrations of ATBI. The results may provide the basis for the selection of non-host inhibitors to develop a H. armigera insecticide formulation.     

Varietal resistance, population dynamics and timing insecticidal application with peak oviposition by Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae) on rice

The flight activity of yellow stem borer Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae) peaked in the months of April-May, May-June, August-September and October. The number of egg masses and the number of adults attracted to light sources were the indicators of S. incertulas flight activity. The rice varieties TKM6, IR22, IR60, IR66 and IR74 were infested at 7, 10, 12 and 16 wk after planting with 5, 10, 20 and 40 neonates of S. incertulas. All varieties except IR66 were susceptible to dead heart damage by S. incertulas. When the rice varieties TKM6, BPIRi2, BPIRi4, IR22, IR36, IR60, IR66 and IR74 were treated with carbofuran insecticide at the time of peak oviposition by S. incertulas in the field, the dead heart damage on all the varieties was significantly reduced in comparison with the untreated plots. Indiscriminate routine insecticidal treatments (fixed schedule) can be replaced by a treat-when-necessary schedule based on the population dynamics of S. incertulas.     

A new genus and three new species of cockroaches (Blattaria: Dictyoptera) from Africa

A new genus Princisaria belonging to family Blaberidae is described from Africa. A key to the African genera of the subfamily Laxatinae is given. Three new species, P. carvalhoi, P. ugandana and P. curta are described.     

DNA-Dependent RNA Synthesis in Isolated Macronuclei of Blepharisma intermedium (Ciliata)

SYNOPSIS. Autoradiographic studies on DNA-dependent RNA synthesis in isolated macronuclei of Blepharisma intermedium in vitro are described. Isolated macronuclei incubated in a medium containing RNA precursors incorporated cystidine and uridine into RNA. Uptake of cystidine was greater than that of uridine. Addition of ATP did not appreciably affect the uptake of precursors into RNA. Actinomycin D (5 μg/ml) blocked incorporation of cystidine and uridine. It is concluded that in isolated macronuclei of Blepharisma , RNA precursors are 1st converted into triphosphates and then incorporated into RNA thru DNA-dependent RNA polymerase.     

沿海拔梯度的表型可塑性影响银胶菊叶甲的取食效率和发育(英文)

【目的】本研究旨在弄清楚生态气候因子是否影响尼泊尔银胶菊Parthenium hysterophorus盛产区中银胶菊叶甲Zygogramma bicolorata成虫后代的形态学测量参数和基础生物学。【方法】 从尼泊尔Kathmandu (24℃, 海拔1 400 m, 温带气候), Chitwan (25℃, 海拔415 m, 热带或亚热带气候)和Mahendranagar (34℃, 海拔229 m, 湿润 亚热带气候)地区采集银胶菊叶甲成虫,在最适室内条件下评估各生态气候区中其F₁代4龄幼虫和雌成虫的取食特征。我们假定在自由取食和最适非生物条件下饲养的后代将不会受到食物和气温的间接影响,不管亲本属于哪一生态气候区,后代利用食物的能力一致。【结果】然而,我们发现,尽管在最适条件下饲养,银胶菊叶甲后代的体型和取食特征与其亲本相似。体型大的亲本(来自Kathmandu地区),其后代体型也大,但是其食物利用效率比体型小的亲本(来自Chitwan 和Mahendranagar地区)所产后代小。这3个生态气候区中,与幼虫相比正在发育的雌成虫均表现出体重增加而食物利用效率降低。【结论】这些发现说明,食物和最适非生物条件的间接影响可能不影响银胶菊叶甲后代的表型可塑性,后代的体型和取食特征与亲本相似。发生的可遗传的变化可能是由于种内的遗传多样性。我们期望这些发现有助于理解气候变化背景下银胶菊叶甲成虫的表型可塑性、分布格局和取食行为。     

Streptomycin- and Penicillin-induced Inhibition of Growth and Pigment Production in Blue-green Algae and Production of Strains of Anacystis nidulans Resistant to these Antibiotics

Relatively low concentrations of streptomycin inhibited thegrowth of Anacystis nidulans and Anabaena variabilis. The productionof chlorophyll, carotenoid, and phycocyanin pigments in thesealgae was significantly but reversibly inhibited by streptomycin.Strains of Anacystis nidulans that are resistant to streptomycinand penicillin were produced by serially subculturing the algain gradually increasing concentrations of the respective antibiotic.These strains seem stable. Evidence which suggests that theresistant strains originate primarily by mutation is presented.     

Natural enemies of Toxoptera aurantii (Boy.) (Homoptera: Aphididae) on cocoa in Ghana

Natural enemies of the black citrus aphid, Toxoptera aurantii (Boy.), on cocoa in Ghana are identified. Biology of some of the natural enemies is followed. Behaviour of the coccinellid and syrphid predators is studied in detail. Effectiveness of the predators in reducing the aphid populations is discussed.