Effects of Total Ginsenosides on the Feeding Behavior and Two Enzymes Activities ofMythimna separata(Walker) Larvae

Ginsenosides, the main effective components ofPanax ginsengC.A. Meyer andPanax quinquefoliusL., are important allelochemicals ofginseng. Although many studies have targeted the pharmacological, chemical, and clinical properties of ginsenosides, little is known about their ecological role inginsengpopulation adaptation and evolution. Pests rarely feed onginseng, and it is not known why. This study investigated the effects of total ginsenosides on feeding behavior and activities of acetylcholinesterase (AChE) and glutathione s-transferase (GST) inMythimna separata(Walker) larvae. The results showed that the total ginsenosides had significant antifeeding activity againstM. separatalarvae, determined by nonselective and selective antifeeding bioassays. In addition, the total ginsenosides had inhibitory effects on the activities of GST and AChE. The antifeeding ratio was the highest at 8 h, then decreased, and was the lowest at 16 h. Both GST and AChE activities decreased from 0 h to 48 h in all total ginsenosides treatments but increased at 72 h. Total ginsenosides had antifeeding activity againstM. separatalarvae and inhibitory effects on the activities of GST and AChE.

AKTIVITAS ANTI MAKAN EKSTRAK DAUN SIRSAK (ANNONA MURICATA L.) DAN PENGARUHNYA TERHADAP INDEKS NUTRISI SERTA TERHADAP STRUKTUR MEMBRAN PERITROFIK LARVA INSTAR V SPODOPTERA LITURA F.

Antifeeding activity of soursop leaf extract (Annona muricata L.) and its effect on nutrition indices and the microscopic structure of peritrophic membrane of the fifth-instar larvae of Spodoptera litura F. were studied. Antifeeding test was conducted by choice method. Discs of caisin leaf were dipped into the ether fraction of soursop leaf extract with concentrations of 0; 0.63; 2.50; and 10.00%. Nutrition indices and peritrophic membrane structure were observed by giving fifth-instar larvae one of the five diets, every group of diet was added to various concentrations of the ether fraction of soursop leaf extract, containing either 0; 0.63; 1.25; 2.50; and 5.00%. The result showed that soursop leaf extract had antifeeding activity at tested concentration 2.50%. Relative consumption rate (RCR), relative growth rate (RGR), and efficiency of conversion of ingested food (ECI) were significantly lower in the case of treated larvae than that of the controls. However the efficiency of conversion of digested food (ECD), approximate digestibility (AD), and peritrophic membrane structure treated with soursop leaf extract were not significantly affected as compared to those in controls.

Antifeeding activity of several plant extracts against Lymantria dispar L. (Lepidoptera: Lymantriidae) larvae

Lymantria dispar L. is the most devastating polyphagous pest of deciduous forests, orchards and urban greenery. To prevent damages that L. dispar larvae cause in forestry, agriculture and horticulture, mechanical measures and the use of biological insecticides are the most frequently applied practices. However, the use of conventional insecticides is inevitable in crop protection and forest management on smaller areas, especially in gradation years. However, inadequate use of these chemicals has led to disturbance of biocoenotic balance, outbreaks of some previously less harmful organisms and pesticide residues in soil and watercourses in some regions. To mitigate these consequences it is necessary to harmonize L. dispar control with integrated management principles by applying selective and less toxic insecticides. Therefore, the potential of botanical insecticides and antifeeding substances is gaining in importance. The aim of this study was to assess the influence of ethanol extracts (1, 2 and 5%) of Ambrosia artemisiifolia L., Erigeron canadensis L., Daucus carota L., Morus alba L. and Aesculus hippocastanum L. on the feeding intensity of L. dispar larvae, i.e. to evaluate their antifeeding activity under the conditions of ?no-choice? test. Ten larvae per repetition were placed in Petri dishes and offered oak leaf slices (2 x 9 cm2/repetition) previously dipped in plant extract or ethanol (1, 2, and 5%) for the control. Feeding intensity, expressed as a percentage of consumed leaf area (%), was measured after 48 h. For assessing the antifeeding activity of plant extracts AFI was calculated and the extracts were classified according to scale: no antifeeding activity, slight antifeeding activity, moderate antifeeding activity and strong antifeeding activity. Data were analyzed using a two-way ANOVA and Duncan`s multiple range test. The results indicate that plant species, i.e. the origin of extracts, had a significant influence on the feeding intensity of L. dispar larvae, while concentration and interaction (plant species x concentration) were not factors of influence. Ae. hippocastanum and M. alba extracts significantly reduced the consumed leaf area (6.24, 18.93%, respectively), compared to the control (97.59%), while the extract of D. carota had a phagostimulative effect (98.88%). Based on AFI values, Ae. hippocastanum extract (87.10-89.05%) had a strong antifeeding activity, and M. alba medium-to-strong (64.33-71.37%).

Synthesis, Characterization, Antifeeding and Insect Growth-Regulating Activities of Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) Complexes with N-Acetylacetonyl-3-Aminocoumarin

Metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized using N-acetylacetonyl-3-aminocoumarin as chelating agent. The ligand behaves as a monobasic tridentate ONO donor towards Ni(II) and as monobasic bidentate ON donor towards other cations. All the complexes have been proposed to have octahedral geometry on the basis of analytical, thermal conductivity, spectral and magnetic data. The complexes have been screened against Spodoptera litura; F (Lepidoptera: noctuiidae) for antifeeding and insect growth-regulating activities The results show appreciable antifeeding and insect growth-regulating activities associated with metal complexation at higher and lower doses respectively. Keywords: Metal complexes; N-Acetylacetonyl-3-aminocoumarin; Antifeeding activity; Insect growth-regulating activity. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: http://dx.doi.org/10.3329/jsr.v2i3.4673 J. Sci. Res. 2 (3), 525-537 (2010)

Antifeedants of Indian Barnyard Millet, Echinochloa frumentacea Link, against Brown Planthopper, Nilaparvata lugens (Stål)

Eight compounds isolated from Indian barnyard millet have been identified as l-malic acid, trans-aconitic acid, (+)-isocitric acid, 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, isocarlinoside, 2″-O-rhamnosylisoorientin, and 7-O-(2″-O-glucuronosyl)glucuronosyltricin, respectively. These compounds showed high antifeeding activity against brown planthopper only when they were combined.

Photorhabdus Virulence Cassettes Confer Injectable Insecticidal Activity against the Wax Moth

ABSTRACT Two recently sequenced genomes of the insect-pathogenic bacterium Photorhabdus and a large Serratia entomophila plasmid, pADAP, have phage-related loci containing putative toxin effector genes, designated the “Photorhabdus virulence cassettes” (PVCs). In S. entomophila, the single plasmid PVC confers antifeeding activity on larvae of a beetle. Here, we show that recombinant Escherichia coli expressing PVC-containing cosmids from Photorhabdus has injectable insecticidal activity against larvae of the wax moth. Electron microscopy showed that the structure of the PVC products is similar to the structure of the antibacterial R-type pyocins. However, unlike these bacteriocins, the PVC products of Photorhabdus have no demonstrable antibacterial activity. Instead, injection of Photorhabdus PVC products destroys insect hemocytes, which undergo dramatic actin cytoskeleton condensation. Comparison of the genomic organizations of several PVCs showed that they have a conserved phage-like structure with a variable number of putative anti-insect effectors encoded at one end. Expression of these putative effectors directly inside cultured cells showed that they are capable of rearranging the actin cytoskeleton. Together, these data show that the PVCs are functional homologs of the S. entomophila antifeeding genes and encode physical structures that resemble bacteriocins. This raises the interesting hypothesis that the PVC products are bacteriocin-like but that they have been modified to attack eukaryotic host cells.

Cloning Serratia entomophila Antifeeding Genes—a Putative Defective Prophage Active against the Grass Grub Costelytra zealandica

ABSTRACT Serratia entomophila and Serratia proteamaculans (Enterobacteriaceae) cause amber disease in the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae), an important pasture pest in New Zealand. Larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. A 155-kb plasmid, pADAP, carries the genes sepA, sepB, and sepC, which are essential for production of amber disease symptoms. Transposon insertions in any of the sep genes in pADAP abolish gut clearance but not cessation of feeding, indicating the presence of an antifeeding gene(s) elsewhere on pADAP. Based on deletion analysis of pADAP and subsequent sequence data, a 47-kb clone was constructed, which when placed in either an Escherichia coli or a Serratia background exerted strong antifeeding activity and often led to rapid death of the infected grass grub larvae. Sequence data show that the antifeeding component is part of a large gene cluster that may form a defective prophage and that six potential members of this prophage are present in Photorhabdus luminescens subsp. laumondii TTO1, a species which also has sep gene homologues.