Phagodeterrence and insecticidal activity of Hyptis suaveolens (Poit.) against four important lepidopteran pests

This study was carried out to evaluate the antifeedant and larvicidal activities of Hyptis suaveolens Poit. (Lamiaceae) leaves crude extracts and their fractions against four lepidopteran pests namely Helicoverpa armigera (Hbn.), Spodoptera litura (Fab.), Earias vittella (Fab.) and Leucinodes orbonalis (G.). Hexane, chloroform and ethyl acetate extracts were tested by leaf disc and fruit disc no-choice methods at 1% and 1,000?ppm concentrations for crude and fractions, respectively. Ethyl acetate extract of H. suaveolens exhibited the maximum antifeedant and insecticidal activity at 1% concentration against all the tested insects. It was subjected to fractionation using silica column chromatography with different combinations of hexane and ethyl acetate used as mobile phase. Among the 15 fractions obtained, fraction 2 showed the maximum antifeedant and insecticidal activity against all tested insects at 1000?ppm concentration. Preliminary phytochemical analysis of fraction 2 showed the presence of terpenoids and alkaloids. H. suaveolens could be considered as a safe and eco-friendly insecticide for lepidopteron pest management.     

Effect of variety and location on growth and yield components of Roselle,HIbiscus sabdariffa L. and its infestation with the spiny bollworm Earias insulana (BOISD.)

Three roselle, Hibiscus sabdariffa L. varieties (Sudani, Masri and White) were cultivated at three different locations to recognize the transportation ability of roselle cultivation from the narrow old valley land to broad new land in Egypt. Qena as origin in situ old land, El-Kanater as ex situ old land and Nubaria as ex situ new land were the considered locations. Six growth quantitative characters and bolls infestation by spiny bollworm, Earias insulana were evaluated. Growth characters of roselle plants were affected significantly by either variety or location. Qena region was more suitable for roselle plant growth as judged with plant height, number of branches, number of fruits and sepals dry weight, followed by Nubaria followed by El-Kanater. Whereas, plants grown at Nubaria produced more fresh sepals weight than Qena or El-Kanater grown plants. As for Sudani, Nubaria exhibited the tallest plants, with the highest number of fruits and the heaviest fresh sepals as compared with the corresponding plants in Qena or El-Kanater. Values of broad sense heritability were highest for all characters in Qena. While the number of fruits per plant had the highest heritability in all locations. Dry sepals yield had highly significant correlation with all studied characters except percentage of water loss in Qena and Nubaria. Path coefficient analysis confirmed that fresh sepals yield had the highest direct and indirect effects on dried sepals yield. Chemical constituents responsible to sepal quality tended to produce significant variations due to the changes in varieties or locations. The highest levels of anthocyanins and sugars were achieved by Sudani variety, but the highest levels of free amino acids and total soluble solids were recorded for Masri variety. Moreover, Nubaria region was the most favourable for the accumulation of more anthocyanins in the sepals of all varieties followed by Qena. Plants grown at Qena produced sepals with the highest levels of sugars, free amino acids, organic acids and total soluble solids, followed by Nubaria followed by El-Kanater plants. Infestation with spiny bollworm Earias insulana was increased from Sudani up to Masri up to White varieties. Plants grown at Nubaria had the lowest number of attacks by bolls in all varieties, followed by those at El-Kanater followed by Qena plants. Spiny bollworm infestation was positively correlated with the number of branches and dry sepals weight, but negatively correlated with sepal moisture loss and anthocyanin contents. These findings clearly indicated that the Nubaria region was considered as a promising reclaimed area suitable for roselle cultivation, especially for Sudani, the most economic variety.     

Evaluation of infestation percentage of cotton fields to the spiny bollworm,Earias insulana Boisduval (Lep.: Noctuidae), and its relationship with pheromone traps

Spiny bollworm, Earias insulana Boisduval (Lepidoptera: Noctuidae), is one of the most important pest of malvaceous plants throughout the world, except America. In recent years, this insect has been serious pest for cotton fields in southern regions of Iran, especially Darab region of Fars province. In order to evaluate the performance of sex pheromone in reduction of infestation percentage of the spiny bollworm by mass trapping method, an experiment was carried out during year of 2012 in Darab region in Randomised Completely Block Design with six treatments and four replications. The treatments were: application of the four sex pheromone trap densities at the rates of 16, 20, 24 and 30?traps/h, application of Larvin chemical insecticide at the rate of 1?L/h and control. Percentages of infected bolls and flowers to E. insulana were weekly determined. The application of Larvin insecticide performed as the pest population reached to economic threshold level. Analysis variance of results showed that there are significant differences between time, trap number and time?×?trap interaction on infestation percentage per hectare. During sampling time, the highest infestation percentage was in control treatment and the lowest one was observed in 30 and 24?traps/h treatments. The peak of infestation percentage was seen in 18th of November. The best efficiency among treatments was observed in pheromone trap. In conclusion, using sex pheromone trap in comparison to application of insecticides can efficiently reduce infestation level of cotton fields.     

Larval growth inhibition of the spiny bollworm,Earias insulana, by some steroidal secondary plant compounds

The effect of 23 secondary plant compounds including a series of steroidal aglycones and glycosides, on larval growth and pupation ofEarias insulana (Boisd.) was investigated. Larvae did not develop when fed on artificial diets containing 0.2% solamargine, solasonine, tomatine, digitonin, saponin, nomilin, lawsone or coumarin. Some growth-retarding activity was found with diets containing 0.2% ajmalicine, capsaicin, quercetin, glycyrrhizin and glycerrhetic acid. The eight compounds highly active at 0.2% were also bioassayed at 0.1, 0.05 and 0.01%: larvae did not pupate when fed on diets containing 0.1% solasonine, tomatine or nomilin, whereas solamargine and coumarin were active even at 0.05%. Preliminary structure-activity relationships were evaluated for the active steroidal glycosides.

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Larvale Wachstumshemmung des ägyptischen Baumwollkapselwurms, Earias insulana,durch einige steroide sekundäre Planzeninhaltstoffe

Zusammenfassung Es wurde die Wirkung von 23, einem künstlichen Nährmedium einverleibten, sekundären Pflanzeninhaltstoffen, unter ihnen eine Reihe steroider Aglucone und Glycoside, auf das Larvenwachstum und die Verpuppung vonEarias insulana untersucht. Larven entwickelten sich nicht in mit 0.2% Solamargin, Solasonin, Tomatin, Digitonin, Saponin, Nomilin, Lawsone und Coumarin versetzten Nährmedien. Auf Medien, die 0.2% Ajmalicin, Capsaicin, Quercetin, Glycyrrhizin and Glycyrrhetinsäure enhielten, war das Larvenwachstum verzögert. Die 8 bei 0.2% hoch wirksamen·Substanzen wurden auch bei 0.1, 0.05 und 0.01% getestet. Die Larven verpupten sich nicht auf 0.1% Solasonin, Tomatin und Nomilin und auf 0.05% Solamargin und Coumarin. Vorläufige Struktur-Wirksamkeit-Beziehungen wurden für die aktiven steroiden Glycoside vorgeschlagen.

     

A single semi‐synthetic diet with improved antimicrobial activity for mass rearing of lepidopteran insect pests of cotton and maize

Helicoverpa armigera (Hübner), Earias vittella (Fabricius), Spodoptera litura (Fabricius), Spodoptera exigua (Hübner) (all Lepidoptera: Noctuidae), Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) are the major pests of cotton and maize. Mass‐rearing of these insects under controlled conditions is necessary to obtain the numbers needed to conduct bioassays to screen insecticides, proteins, and other compounds, as tools for insect pest management. We present a diet suitable for rearing the six lepidopteran pests (five cotton and one maize pest). We further show that this diet is on par with or superior to the published diet recipes for each of the insect species, which were studied for three generations. We also discuss the advantages of antimicrobials other than formalin for keeping microbial growth under check. A combination of antimicrobial solution and benomyl provided effective control and suppressed the growth of microbes for a longer period than a formalin‐containing diet. A common diet for six pests provide opportunities for automation of diet preparation in addition to improved throughput and consistency in the process, while eliminating diet‐batch related errors.     

Host influence on mating behavior and spermatophore reception correlated with reproductive output and longevity of femaleEarias insulana (Boisduval) (Lepidoptera: Noctuidae)

When mating and oviposition behavior ofEarias insulana were studied in the absence or presence of host or by providing only host odor, in comparison to other treatments host absence caused a delayed and reduced reproductive activity with occasional impairment of egg viability. Presence of host or its odor resulted in a short premating period and a significant increase in mating frequency, number of spermatophores transferred, number of eggs oviposited, and proportion of eggs fertilized. Compared to host odor, host accessibility had a larger impact on insect behavior, indicating the importance of host cantact. Under conditions of host accessibility, there existed a significant and positive correlation between the number of spermatophores received by a female and both the number of eggs she oviposited and her longevity. This indicated a role for male-derived nutrients in the reproduction ofE. insulana.