Plant-derived essential oils affecting settlement and oviposition of Bemisia tabaci (Genn.) biotype B on tomato

The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is an economically important pest of tomatoes Solanum lycopersicum (L.), causing irregular ripening on fruits and transmitting several plant pathogenic geminiviruses. The management of this pest is commonly based on repetitive spraying with synthetic pesticides, causing serious environmental damages and increase of resistance by insect population. In the present study, essential oils from the leaves of Artemisia camphorata Vill., Ageratum conyzoides L., Foeniculum vulgare Mill., Lippia alba (Mill.) N. E. Br., Plectranthus neochilus Schltr., and Tagetes erecta L. were investigated for their possible repellent and oviposition-deterrent effects against B. tabaci biotype B on tomato. In a multi-choice assay, P. neochilus essential oil was the most active repellent and oviposition deterrent. Essential oils of A. conyzoides and T. erecta significantly deterred the female B. tabaci biotype B from laying eggs on treated tomato leaflets compared with the control. (E)-Caryophyllene (30.67 %) and the monoterpenes α-pinene (15.02 %) and α-thujene (11.70 %) were identified as the major constituents of the essential oil of P. neochilus. Our findings demonstrated the potential of essential oil of P. neochilus and other oils in the reduction of settlement and oviposition of B. tabaci biotype B on tomato.     

Über die Bevorzugung von Blatthaaren zur Eiablage bei Bemisia tabaci (Genn.) (Hom., Aleyrodidae)

Studies on the egg laying byB. tabaci showed this pest fixing its eggs at the basis of leaf hairs of cotton plants. The rejection of none hairy-leaved cotton varieties is apparently due to the lack of suitable egg laying sites. Moreover, the preference of the whitefly for leaf hair sites for egg laying explains reasonably why the hairy-heaved, jassid—resistant cotton varieties are more attractive to whitefly. The indiscriminate behaviour of egg laying mentioned byGameel (1974) may be possible on glabrousleaved host plants.     

乌头提取物对蜀柏毒蛾生物活性研究

毒力测定表明,乌头乙醇提取物对蜀柏毒蛾有较高毒力,24 h致死中浓度LC50为168.9μg/g。室内试验表明800μg/g和600μg/g两个剂量对蜀柏毒蛾均有明显的药效,随着施药时间的增加,死亡率逐渐增大,施药72 h后的校正虫口退减率分别达到100%和95.13%,与0.3%印楝素乳油1 200倍液无显著差异。根据上述结果,讨论了利用乌头提取物开发和研制新型植物源农药的前景。     

Influence of host plant species of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) on some of the biological and ecological characteristics of the entomophagous Serangium parcesetosum Sicard (Col., Coccinellidae)

The entomophagous Serangium parcesetosum Sicard (Col., Coccinellidae) is an effective predator of some whitefly species. However, information on the influence of the preys host plant species on its biological and ecological characteristics is still lacking in the literature. Therefore, the current study focuses on the possible influence of three greenhouse and two field host plant species of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) on the number of eggs laid by S. parcesetosum. In addition, because of the economic importance and widespread planting of cucumber in greenhouses and cotton in the field, these plants were selected for further investigation into the development, mortality, longevity and reproduction of S. parcesetosum at a high temperature in the laboratory. Results showed that S. parcesetosum was able to lay eggs on all five host plant species of B. tabaci, whether greenhouse or field plants. However, among the three greenhouse plant species studied, S. parcesetosum females laid the highest number of eggs on cucumber followed by tomato and then sweet pepper. Of the two field plant species, significantly higher numbers of eggs were laid on tobacco than on cotton. S. parcesetosum could develop either on cucumber or on cotton as preferable host plant species for B. tabaci. There were significant differences in mean developmental duration of larval instars of the same sex between both host plant species; the duration was significantly shorter on cucumber than on cotton. There were no significant differences for mean total developmental duration from egg to adult emergence between both host plant species within the same sex; females showed a mean of 15.9 days and males of 15.1 days on cucumber, while on cotton the means were 17.2 days for females and 16.2 days for males. Total mortality percentage of S. parcesetosum during development from egg to adult stage was lower on cucumber than on cotton, 20.6 and 23.8%, respectively. Longevity of S. parcesetosum varied according to host plant species and sex with a mean of 63.4 days for females and 50.3 days for males on cucumber, and 92.4 days for females and 52.5 days for males on cotton. On cucumber, mean period of oviposition of S. parcesetosum was significantly longer than on cotton. Mean total fecundity was significantly higher on cucumber than on cotton, with means of 97.7 and 31.0 eggs/female, respectively.     

Efficiency of neem and groundnut oils in protecting leguminous tree seeds against seed beetles in the Sahel

The objective of our study was to test the comparative efficiency of neem (Azadirachta indica) kernel oil, groundnut oil and a synthetic insecticide, K-Othrine®, in protecting stocks of leguminous tree seeds against seed beetles under Sahelian conditions. The following insect/seed combinations were used as models: Caryedon acaciae/Acacia nilotica, C. longispinosus/A. raddiana and C. serratus/Tamarindus indica. Neem oil, when used at concentrations of 5 to 20 ml per kg of seeds, had pronounced adulticidal and ovicidal effects which were maintained for five months. No significant fall in seed viability was observed except in the case of C. acaciae/A. nilotica. Groundnut oil, when used at concentrations of 5 to 20 ml per kg of seeds, had pronounced adulticidal and ovicidal effects which were relatively short-lived. A significant fall in seed viability was observed over five months. K-Othrine®, when used at concentrations ranging from 25 to 100 mg per kg, had high adulticidal effects which were maintained for five months. However, K-Othrine® was found to have no ovicide properties. No significant fall in seed viability was observed. This study concluded that it is possible to use neem oil, a product that can be obtained locally at low cost, to efficiently protect tree seed stocks in the Sahel.This revised version was published online in November 2005 with corrections to the Cover Date.     

Evaluation of two Neem seed kernel extracts againstLiriomyza trifolii (Burg.) (Dipt. Agromyzidae)

Laboratory evaluation of Neem Azal-S and Margosan-O was carried out against the adult and larvae ofLiriomyza trifolii Burgess. The feeding deterrent activity of both compounds was significantly realized against the adults particularly at high concentrations which lasted for 5 days after treatment. Both formulations also deterred the females from laying eggs and the percentage of oviposition deterrent index (ODI) reached 80.7 and 52.6 for Neem Azal-S and Margosan-O (2%), respectively.Post infestation treatment of bean seedlings containing 3rd instar larvae indicated that the toxic action of the tested extracts was quite limited. However, different percentages of malformed pupae were obtained. The sex ratio between the resulting adults was nearly unaffected with the exception of individuals whose larvae were treated with 2% Neem Azal-S where all the resulting progenies were females.With 2 tables     

Bioactivity of Pelargonium graveolens essential oil and related monoterpenoids against sweet potato whitefly,Bemisia tabaci biotype B

Journal of Pest Science - The sweet potato whitefly, Bemisia tabaci Gennadius biotype B (Hemiptera: Aleyrodidae), causes high economic losses in vegetables, beans, soybeans, peanuts, cotton, and...     

Prey consumption by larval and adult stages of the entomophagous ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) of the cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae), at two different temperatures

The entomophagous ladybird, Serangium parcesetosum Sicard (Col., Coccinellidae) appears to be a promising predator against the cotton whitefly, Bemisia tabaci (Genn.) (Hom., Aleyrodidae). Knowledge about its consumption of B. tabaci is incomplete. The present study was undertaken to determine the potential use of this predator in biological control programs. The daily and total prey consumption of S. parcesetosum through the entire development of the larval instars as well as during three different periods of longevity of adult females and males feeding on nymphs or puparia of B. tabaci as prey was examined. In addition, the daily prey consumption of the adult females where the number of B. tabaci puparia was altered was studied at two different temperatures in the laboratory. The results showed that the mean daily prey consumption of nymphs or puparia of B. tabaci by larval instars of S. parcesetosum increased gradually as development progressed at both temperatures. Significant differences were found in the mean total prey consumption among the different predatory larval instars. In total, S. parcesetosum consumed during its entire larval development significantly more nymphs than puparia; at 18°C it consumed a mean of 1,566.1 () and 1,443.9 () nymphs or 280.0 () and 250.8 () puparia, while at 30°C, it consumed a mean of 1,119.1 () and 979.9 () nymphs or 188.2 () and 171.6 () puparia. Over the three studied periods of the adult stage of S. parcesetosum, the mean daily prey consumption by the females and males fluctuated irregularly at both temperatures. At 18°C and 30°C, both females and males consumed significantly more nymphs than puparia. No significant differences were found between females and males with respect to consumption of nymphs, although significant differences were found between the sexes with respect to consumption of puparia, but at 18°C only. The mean total prey consumption over the three studied adult stages was 2,188.4 () and 1,994 () nymphs or 727.1 () and 624.8 () puparia at 18°C, while at 30°C the mean values were 3,947.7 () and 3,577.3 () nymphs or 1,600.5 () and 1,448.8 () puparia. S. parcesetosum adapted smoothly to fluctuating prey availability, where the mean daily prey consumption became higher when 50 puparia/day was offered. In contrast, the predator consumed most individuals when the number of prey supplied was 10 or 5 puparia/day. Prey consumption decreased during the second experimental week in the trial, before which 50 puparia/day had been offered. In the other trials, before which 20, 10 and 5 puparia/day had been offered, a considerable increase in prey consumption was noted.This paper is dedicated to Prof. Dr I. Akif Kansu, University of Ankara, Turkey on his 80th birthday.     

金银忍冬种子浸提液对白菜种子萌发的影响

该文通过金银忍冬种子的不同提取液对白菜种子的发芽试验,探讨金银忍冬种子休眠及萌发率低的原因。     

Impact of neem and chinaberry fruit extracts on the pest/parasitoid (Pieris rapae/Hyposoter ebeninus) interactions

A new technique was performed to simulate exposure of the host Pieris rapae larvae to both botanical treatment and the parasitoid Hyposoter eheninus in different sequences. It was found that: host larvae subjected to both parasitoid and 1?% neem treatment showed significant or insignificant reductions both in pupal formation as well as adult emergence percentages when treatment preceded or followed parasitism, respectively. Both neem treatments revealed significant prolongation in the development of unparasitized and parasitized larvae (on average 4 to 5 days delay), whereas chinaberry caused significant prolongation only among parasitized larvae (on average 2.7 days delay in egg-larval duration). Fate of parasitism among untreated hosts was found to be faster than among neem-treated ones. Parasitism percentages among 1 and 0.5?% neem-treated third instar host larvae held 7 days before parasitism reached 3 and 2 times that achieved among those reared on untreated diet for the same period, ­respectively. It was concluded that prolongation of the preferred target instars of the host, due to neem treatments, increased the chance for parasitism. Nevertheless, treatment with neem at the LC₅₀ level exhibited a great reduction in parasitoid progeny. However, a lower concentration (LC₂₅) could reasonably potentiate parasitism without drastic losses in parasitoid emergence.     

雷公藤总甙对马尾松毛虫生物活性的影响

以无水乙醇为溶剂,用连续回流渗漉法从雷公藤生药中提取出粗提物。经乙酸乙酯纯化后得红褐色的浸膏,经检测为总萜内酯（T1）。就其杀虫活性和作用方式进行了较系统的生物测定。结果表明：T1对马尾松毛虫具有强的拒食、麻醉和毒杀作用,毒杀中浓度LC50为1548．50mg／L,拒食中量AFD50为12．25μg／条,麻醉中量ND50为103．98μg／g,无触杀作用;T1不仅抑制马尾松毛虫幼虫的生长发育．还影响其蛹的羽化和卵的孵化及初孵幼虫存活;抑制中浓度EC50为952．65mg／L;在T1浓度10～10000mg／L之间,马尾松毛虫蛹不完全羽化率为43．3％～63．3％。其卵的不能孵化率为12．0％～84．0％,孵化的幼虫存活率为0．0％～95．6％。     

Toxicity of some pesticides against the egg stage and the first larval instar of the chrysopid predatorChrysoperia carnea (Steph.)

The toxicity of cypermethrin, deltamethrin, fenpropathrin, fenvalerate, methomyl and kelthane-s against the egg stage and the 1st larval instar ofChrysoperla carnea (Steph.) revealed that deltamethrin exhibited magnitude bad side effects against the eggs (LC₉₀=3.35 ppm) as compared with the safest compound kelthane-s (LC₉₀=144 ppm); the figures of the other tested toxicants ranged between 17.6 and 109.2 ppm.It was found that the larval stage needed higher concentrations to achieve similar mortality percentages. LC₉₀ values ranged between 72.2 and 1,176 ppm. Ranking of toxicity was, however, similar to that of ovicidal action.With one table     

The activity of some compounds extracts byAllium on stored-product insectsOryzaephilus surinamensis (L.),Sitophilus oryzae (L.) andTribolium castaneum (Herbst)

The bioactive metabolites of someAllium plants, all exhibiting interesting pharmacological activities, were tested for their attractive/repellent activity against saw-toothed grain beetle,Oryzaephilus surinamensis (L.), rice weevil,Sitophilus oryzae (L.), and rust-red flour beetle,Tribolium castaneum (Herbst), insects infesting the stored-products. The data obtained showed significant repellent effect of the thiosulfinates againstS. oryzae. Part 6 in the series “Chemistry of the genus Allium”.     

植物生物碱的杀虫作用及应用

植物生物碱是植物在与昆虫协同进化过程中形成的一大类具有防御功能的次生代谢物质,在害虫综合治理中具有非常重要的作用。本文对植物生物碱的杀虫作用方式、作用机理和作为杀虫剂、昆虫拒食剂、驱避剂、产卵忌避剂的应用以及作为先导化合物在新农药创制中的作用做了综述,并对植物生物碱的研究前景进行了展望,提出了今后研究和开发应用中注意的问题。     

基质配方对黄樟无纺布容器育苗的影响

为高效培育黄樟壮苗,本文以黄心土、稻谷壳和泥炭土为育苗基质原料,按照不同比例配置19种基质配方,来进行无纺布容器育苗基质配方试验,通过对1年生苗木苗高、地径、生物量、侧根生长情况、叶绿素含量、光合速率的测定和分析,综合评价值及育苗基质成本等条件来筛选出适宜培育黄樟容器苗的基质配方.试验结果表明:黄樟适宜的基质配方为泥炭土:稻谷壳:黄心土=7:2:1,使用该基质配方培育的1年生黄樟容器苗平均苗高可达86.2 cm,平均地径可达0.80 cm.     

Efficacy of neem oil against thrips (Thysanoptera) on mango panicles and its compatibility with mango pollinators

A field trial was conducted in a mango (Mangifera indica L.) orchard located on Penang Island, Malaysia, to determine the efficacy of neem oil at 1, 2 and 3% concentrations and imidacloprid, a commonly used synthetic insecticide, on populations of thrips and their toxicities to mango pollinators. Daily periodicities of several pollinators that frequently visited mango panicles were studied prior to the insecticide trial to determine the appropriate time of insecticide application. Pollinators were collected at 2-h intervals for 2?months in the dry season and 1?month in the wet season of 2009. Mean numbers of all pollinators were greater in the morning (0800?h) and peaked in the late afternoon, but remained low during other times of the day. After two consecutive applications at 7-day interval, both neem oil and imidacloprid effectively reduced thrips populations compared to an untreated plot. Imidacloprid was the most effective insecticide reducing 68.7% thrips adult and 80.7% larval populations, respectively. However, it caused 92.5% mortality in pollinator populations. Neem oil at 2% was effective against adult thrips 96?h after the second application (59.8% reduction) and caused only 24.9% mortality of pollinators. Proper timing of neem oil application such as at midday when pollinators are least active would control thrips populations satisfactorily but less detrimental to mango pollinators. Future improvement of neem oil formulation should be aimed at improving its efficacy against thrips and further reducing toxicity to pollinators.     

雷公藤总生物碱的提取及对东亚飞蝗的生物活性检测

提取、分离了雷公藤Tripterygium wilfordii根皮中总生物碱物质,采用小叶蝶添加法测定其对东亚飞蝗Locustas migratoria拒食、生长发育及毒杀等生物活性.结果表明:雷公藤总生物碱对3龄东亚飞蝗具有拒食、生长发育抑制和毒杀作用.48 h非选择性拒食中浓度AFC_(50)、生长发育抑制中浓度EC_(50)48 h毒杀中浓度LC_(50)分别为236.84 mg/L、151.96 mg/L和171.72 mg/L;雷公藤总生物碱对东亚飞蝗无明显触杀作用.     

Effects of livestock on seed germination of guava (Psidium guajava L.)

This paper reports on the effects that livestock have on seed germination of guava (Psidium guajava L.). Experiments here reported were intended to simulate gastric scarification using different soaking periods in a 0.01 N HCl solution alone or combined with rumen treatments. Additional experiments evaluated germination of defecated and nondefecated seeds germinated in petri dishes and in cow dung.Passage through the digestive tract of cattle did not affect seed germination of guava. Lowered germination was obtained for seeds germinated in cow dung as compared to laboratory germinated seeds. Nevertheless this difference may reflect an inadequate surface-volume ratio of the cow pat used. Large variations in germination between years were recorded. Nothing is known about the effects this may have on the ecology of pasture invasion by guavas.