Influence of nonhost plant diversity and natural enemies on the potato leafhopper, Empoasca fabae, and pea aphid, Acyrthosiphon pisum, in alfalfa

We examined the effects of nonhost plant diversity and predators on the potato leafhopper, Empoasca fabae (Harris), the pea aphid, Acyrthosiphon pisum (Harris), and their primary host plant, alfalfa, Medicago sativa L. Potato leafhopper intensity (i.e., leafhoppers/alfalfa stem density) and plant damage (i.e., hopperburn) were significantly greater in alfalfa mono- than in polycultures of alfalfa mixed with nonhost plant species. There was no significant effect of nonhost plant diversity on pea aphid intensity or on predator abundance. Predator:prey ratios were higher in poly- than in monoculture. One predator, Nabis sp., was selected for further study. A microcosm experiment indicated that Nabis is an effective predator of both herbivores, and suggested that nonhost plant diversity may enhance the predation of leafhoppers by Nabis. These results suggest that nonhost plant diversity and Nabis limit leafhopper populations and protect alfalfa from herbivory. The potential for nonhost plants to increase herbivore movement and vulnerability to predation is discussed.     

Antifeedant activity of flavonoids and related compounds against the subterranean termiteCoptotermes formosanus Shiraki

Antifeedant activity of some flavonoids and their related compounds against the subterranean termiteCoptotermes formosanus Shiraki was examined with nochoice tests and two-choice tests. The activities of these compounds were evaluated in relation to their chemical structures. All flavonoids tested showed antifeedant activity, whereas catechinic acid, possessing no A-ring or pyran ring in the molecule, showed feeding-preference activity. For the structure-activity relations, it was found that compounds containing two hydroxyl groups at C-5 and C-7 in A-rings showed high antifeedant activity. Furthermore, the presence of a carbonyl group at C-4 in the pyran rings of the compounds was necessary for the occurrence of high activity. 3-Hydroxyflavones and 3-hydroxyflavanones with 3,4-dihydroxylated B-rings exhibited higher activity than those with 4-hydroxylated B-rings.Part of this paper was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999     

Antifeedant activity of some diterpenoids

The antifeedant activity of six diterpenes against the fourth instar nymphs and adults of Henosepilachna vigntioctopunctata was evaluated using a dual choice leaf disc bioassay. Caryoptin was the most effective antifeedant among the compounds tested. Andrographolide, wightionolide and 3-epicaryoptin did not deter feeding by adults. The possible relationship of structure to antifeedant activity is discussed.     

Antifeedant activity of quinones from Ventilago madaraspatana.

The insect antifeedant activity of the quinones isolated from Ventilago madaraspatana was investigated by circular leaf disc dual choice bioassay. Amongst the quinones tested, Ventiloquinone A was the most effective antifeedant against Henosepilachna vigintioctopunctata and Spodoptera litura.     

Antifeedant activity of vicolides from Pentanema indicum

Vicolides A–D (0.2–2000 ppm) from Pentanema indicum showed antifeedant activity against Euproctes fraterna and Pericallia ricini V stage larvae.     

Antifeedant activity of Momordica dioica fruit pulp extracts on Spodoptera litura

The hexane extract and ethyl acetate soluble fraction of methanolic extract of the fruit pulp of Momordica dioica exhibited moderate and concentration dependent antifeedant activity against Spodoptera litura.     

Efficacy of Neem-Azal S and Margosan-0 against the bean aphid,Aphis fabae Scop.

Margosan-0, a commercial preparation of neem seed kernel extract was tested for its effects as toxicant, deterrent and sterilant against the bean aphidAphis fabae and compared with the German product Neem-Azal S. Second and 4th nymphal instars ofA. fabae, placed on bean plants treated with different concentrations of Margosan-0 or Neem-Azal S, were adversely affected and very high percentage of mortality occurred after 96 hours. In a choice test, higher numbers of adults settled and larviposited on plants treated with Margosan-0 in comparison to the control. Neem-Azal S treated plants showed high deterrence to the adults at high concentrations. The deterrent effect was reflected in a reduced larviposition. Plants treated with different concentrations of either Neem-Azal S or Margosan-0 significantly affected the longevity and fecundity ofA. fabae. The efficacy of Neem-Azal S is more pronounced than that of Margosan-0.     

Virus vector aphid activity and seed potato tuber virus infection in Hungary

An aphid and virus survey was conducted from 1993 and 1999 on the eastern lowlands in Hungary. Aphid flight was monitored with two yellow pan traps placed on the edge and in the middle of seed potato fields. From 1993 and 1997, aphid flight was monitored with a Rothamsted type suction trap. The aphid and virus survey was continued in four different regions of Hungary in 2000. Aphid flight activity recorded by the suction trap and the yellow pan traps was different. Cumulative vector intensity based on yellow pan trap catches revealed a greater variation between years than among the different locations. In 4?years out of 8, aphid flight was less intensive and quality seed potato was harvested regardless of the production site. Cumulative vector intensity is a good means to forecast the time of haulm destruction in seed potatoes.     

Cereal aphid flight activity in Hungary and England compared by suction traps

Cereal aphid flight was monitored by 12.2 m suction traps at Szolnok in the middle of the Great Hungarian Plain and at Rothamsted, UK. Flight activities of Rhopalosiphum padi, Metopolophium dirbodum and Sitobion avenae were compared by the cross correlation function (CCF) between Hungary and UK. There was significant synchrony between flight a-tivity in Hungary and UK of R padi, M. dirbodum and S. avenae based on the eight years weekly sample data. The peak flight occurred 1, 3 and 2 weeks later at Rothamsted than at Szolnok for the three species (the CCF values were at – 1 week lag, r = 0.854, – 3 week lag r = 0.809, – 2 week lag r = 0.883, P < 0.05 respectively). When the flights in individual years were compared within species and between places the syn-chrony was lowest for R. padi: – in 4 years out of 8 and there was no synchrony, in the other years when synchrony occurred the time lag varied between – 1 week and – 4 weeks. For M. dirhodum the time lag varied between 1 and – 5 weeks, the synchrony was the best for S. avenae the week lag varied between 0 and – 3 weeks.Our results show that flight activity of cereal aphids at Szolnok occurs 1-3 weeks earlier than at Rothamsted. The crop season is earlier in Hungary than in England.     

3-Prenyl luteolin,a new prenylated flavone with melanin biosynthesis inhibitory activity from wood of Artocarpus heterophyllus

In our efforts to find new whitening agent from natural resources, we focused on wood of Artocarpus heterophyllus which shows anti-melanogenesis activity. By activity-guided fractionation of A. heterophyllus wood extract, a new prenylated flavonoid, 3-prenyl luteolin (1) was isolated. The IC₅₀ of mushroom tyrosinase inhibitotry activity of 1 was 76.3 µM. The results of the comparison with that of luteolin showed the prenyl substituent at C-3 position of 1 play an important role for revealing tyrosinase inhibition. In melanin formation inhibition on B16 melanoma cells, IC₅₀ of 1 was 56.7 µM with less cytotoxicity.     

Temperature-dependent functional response of two aphid parasitoids, Aphidius colemani and Aphidius matricariae (Hymenoptera: Aphidiidae), on the cotton aphid

The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2–64 third-instar nymphs of A. gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A. colemani increased linearly as the temperature increases from 10 to 30°C, but in A. matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical dome-shaped pattern. The highest instantaneous attack rate for A. colemani and A. matricariae were calculated 0.940 ± 0.144 day⁻¹ at 30°C and 0.687 ± 0.157 day⁻¹ at 25°C, respectively. Handling time (T _h) for A. colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A. matricariae, (T _h) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A. colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A. colemani maybe more effective for biological control of the cotton aphid during warmer periods.     

华山松出现丛枝与蚜虫及螨危害的关系

对华宁县东山林场、楚雄紫溪山林场及东川202林场等地华山松人工纯林的野外调查、标本鉴定及对危害病状进行分析表明：华山松人工纯林出现大面积丛枝、衰退与华山松球蚜、云南松大蚜及螨的危害有关。受害寄主顶枝生长受到抑制，节间缩短，生长停滞，甚至枯死；侧芽生长，形似扫帚状；球果发育不良，结果量、产籽量减少；整个植株生长势衰弱。危害部位主要是中幼林的主枝顶芽及大树的侧枝顶芽。     

Transgenic expression of Pinellia ternata agglutinin (PTA) and Arisaema heterophyllum agglutinin (AHA) in wheat confers resistance against the grain aphid,Sitobion miscanthi

Journal of Pest Science - The present study investigated the feeding behaviour and life-table parameters of the grain aphid Sitobion miscanthi in response to being fed on transgenic wheat lines...     

Pharmacokinetic study of luteolin,apigenin, chrysoeriol and diosmetin after oral administration of Flos Chrysanthemi extract in rats

Flos Chrysanthemi (the flower of Chrysanthemum morifolium Ramat.) is widely used in China as a food and traditional Chinese medicine for many diseases. Luteolin and apigenin are two main bioactive components in Flos Chrysanthemi, and chrysoeriol and diosmetin are two methylated metabolites of luteolin in vivo by cathechol-O-methyltransferase (COMT). However, there was lack of pharmacokinetic information of chrysoeriol and diosmetin after oral administration of Flos Chrysanthemi extract (FCE). The present study aimed to develop an HPLC-UV method for simultaneous determination of rat plasma concentration of luteolin, apigenin, chrysoeriol and diosmetin and utilize it in pharmacokinetic study of the four compounds after orally giving FCE to rats. The method was successfully validated and applied to the pharmacokinetic study when oral administration of FCE to rats with or without co-giving a COMT inhibitor, entacapone. Chrysoeriol and diosmetin were detected in rat plasma after oral administration of FCE and their concentrations were significantly decreased after co-giving entacapone. Furthermore, AUC of luteolin was significantly increased by entacapone, while that of chrysoeriol was decreased by entacapone, which revealed COMT might play an important role in the disposition of luteolin in rats after dosing of FCE. In conclusion, a sensitive, accurate and reproducible HPLC-UV method for simultaneous determination of luteolin, apigenin, chrysoeriol and diosmetin in rat plasma were developed, pharmacokinetics of chrysoeriol and diosmetin combined with luteolin and apigenin were characterized after oral administration of FCE to rats, which gave us more information on pharmacokinetics and potential pharmacological effects of FCE in vivo.     

Larvicidal activity of a botanical natural product, AkseBio2, against Culex pipiens

A botanical natural product, AkseBio2, was evaluated for its larvicidal effect against Culex pipiens under laboratory conditions. The product exhibited strong larvicidal activity and caused >90% mortalities in both the young (first-second) and the older (third-fourth) larval stages of the species at 24 h at the doses of 25 and 50 ppm. However, it was determined that the young larval stages were more susceptible to the product in comparison with the older larval stages. The results suggest that the product is promising as a larvicide against C. pipiens and could be useful in the search of new larvicidal natural compounds.     

Antiviral activity of betulin,betulinic and betulonic acids against some enveloped and non-enveloped viruses

Antiviral properties of betulin, betulinic and betulonic acids were investigated in cell cultures infected with herpes simplex type I, influenza FPV/Rostock and ECHO 6 viruses. All studied triterpenes were active against herpes simplex virus. Betulin and especially betulinic acid also suppressed ECHO 6 virus reproduction.     

苦豆草生物碱对柳蓝叶甲的拒食作用

研究苦豆草生物碱对柳蓝叶甲取食的影响.结果表明:苦豆草生物碱总碱及其单体对柳蓝叶甲具有较强的拒食作用,且随着浓度的升高拒食作用增强.在选择性取食条件下,随着总碱处理浓度的升高,试虫对处理叶的取食量迅速下降;而对未处理叶的取食量没有显著的差异,但随着处理浓度的升高,总取食量明显下降.在供试的6种生物碱单体中,苦豆碱和槐胺碱对柳蓝叶甲的拒食活性较强.其中处理浓度为5 mg·mL-1时,在选择性取食条件下,苦豆碱的拒食率高达99.4%,而在非选择性取食条件下,则以槐胺碱的拒食活性较强,达91.7%.     

A HPTLC densitometric determination of luteolin in Thymus vulgaris and its extracts

Luteolin content in Thymus vulgaris and its extracts have been compared. Luteolin was separated on a thin- layer of silica gel with three-step gradient elution and determined by HPTLC-photodensitometry. The proposed method is simple and sensitive and can be used for the routine assay of luteolin in phytomedicines containing thyme extracts.     

Molluscicidal activity against Oncomelania hupensis of Ginkgo biloba

In search for molluscicidal active components, petroleum ether, ethyl acetate, ethanol, and water extracts from Ginkgo sarcotesta were evaluated against the snail Oncomelania hupensis. The bioassay-oriented showed that the activity concentrates in the petroleum ether extract (LD(50) 7.81 ppm). Ginkgolic acids, isolated from the petroleum ether extract, exhibited strong molluscicidal activity (LD(50) 1.49 ppm), gingkgolic acid C15:1 having the strongest molluscicidal activity.