五爪金龙凋落叶腐解物的化感潜力研究

采用莴苣种子为受体,测试了五爪金龙凋落叶早期腐解物的化感作用,并与其鲜叶及凋落叶的化感潜力进行了比较分析。结果如下:凋落叶40d的腐解物、鲜叶及凋落叶的水提取液均具有较强的化感潜力,并表现出低促高抑的浓度效应,在FW0.1g﹒mL-1高质量浓度下的综合化感抑制强度为凋落叶未能加土壤的腐解物>鲜叶>凋落叶加土壤的腐解物>凋落叶,而在FW0.005g﹒mL-1低质量浓度下的综合化感促进作用是凋落叶>鲜叶>凋落叶加土壤的腐解物>凋落叶未加土壤的腐解物。鲜叶的抑制强度较凋落叶的大,表明叶片在衰老过程中抑制作用减弱。凋落叶未加土壤仅在空气微生物作用下的腐解物抑制作用最强,促进作用最小,而加入土壤后在土壤微生物作用下的腐解物的抑制作用却有所减弱,抑制强度介于鲜叶和凋落叶的之间,促进作用却小于鲜叶和凋落叶,说明凋落叶腐解过程中微生物的参与对化感作用产生了复杂的影响。     

黄地老虎NPV增效作用的研究

对黄地老虎核型多角体病毒（ＡｓＮＰＶ）的多角体蛋白和病毒粒子组分进行分离纯化,分别与棉铃虫核型多角体病毒（ＨａＮＰＶ）混合感染三龄棉铃虫幼虫,发现此二种组分均能够提高棉铃虫幼虫的死亡率,缩短半致死时间,降低半致死浓度。使用酶联免疫吸附测定（ＥＬＩＳＡ）技术检验ＡｓＮＰＶ多角体蛋白和病毒粒子与粘虫颗粒体病毒增效因子（ＰｓＧＶ－ＳＦ）和ＨａＮＰＶ多角体蛋白的同源性,发现ＡｓＮＰＶ多角体蛋白和病毒粒子与     

Toxicological and larvicidal activities of Alzanzalakhet,Melia azedarach against cucurbit fly,Dacus ciliatus at Hail Province in Saudi Arabia

Alzanzalakhet, Melia azedarach L. (Sapindales: Meliaceae) is a common medicinal plant which is found in Hail desert in Saudi Arabia and traditionally used for various purposes. In this study, toxin effectiveness of the ethanolic, acetonic, and aqueous extracts of M. azedarach leaves was tested to determine a larvicidal activity against the cucurbit fly, Dacus ciliatus (Loew) (Diptera: Tephritidae). Different treatments with M. azedarach extracts varied significantly in their impact on mortality of D. ciliatus larvae. Results showed that all tested extracts in the three solvents exerted a positive pattern for reducing larvae of D. ciliatus. However, the ethanolic M. azedarach extract was the most potent compared with other tested solvents. The highest mortality of the D. ciliatus larvae was shown to be 94%, 74%, and 68% when the concentration was 1?×?10⁵?ppm for ethanolic, acetonic, and aqueous extracts, respectively. In contrast, the concentration 1?×?10¹?ppm resulted in the lowest mortality of D. ciliatus larvae at 40%, 34%, and 12% for ethanolic, acetonic, and aqueous extracts, respectively. Overall, the results of this study suggest that the ethanolic extract of M. azedarach leaves may be used as a sustainable method for controlling D. ciliatus larvae.     

Leaf surface compounds of the potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis>) and their influence on Colorado potato beetle (<Emphasis Type="Italic">Leptinotarsa decemlineata</Emphasis>) feeding

Summary.  The sampling behavior of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) involves examination of the surface of potato leaves. It has been suggested that leaf surface compounds (volatiles and cuticular waxes) may be involved in host-plant recognition, acceptance or discrimination. Here we report on the effect of leaf surface extracts of six Polish commercial potato varieties on CPB feeding. We tested the influence of potato leaf surface extracts on CPB adult and larval feeding, then separated the extracts with HPLC, and finally tested the effect of the HPLC-separated fractions on CPB feeding. The bioassays were performed using potato leaf discs deprived of their original surface compounds. Applied to test discs at concentrations ten times higher than natural (10 leaf area equivalent), the extracts deterred CPB adults and larvae from feeding. HPLC-separated fractions composed of alkanes, sesquiterpene hydrocarbons, wax esters, benzoic acid esters, fatty acid methyl, ethyl, isopropyl and phenylethyl esters, aldehydes, ketones, methyl ketones, fatty acids, primary alcohols, β-amyrin and sterols did not affect adult CPB feeding. Similarly, alkanes, sesquiterpene hydrocarbons, wax esters, methyl ketones, sesquiterpene alcohols and secondary alcohols had no effect on larval CPB feeding. The sterol fraction (cholesterol, β-sitosterol and stigmasterol) acted as a phagostimulant to CPB larvae. We isolated a fraction demonstrating a phagodeterrent effect on CPB adults and larvae. The qualitative composition of the deterrent fraction was quite similar in all potato extracts, but there were quantitative differences between the varieties. Much further work is needed to identify the compounds that can produce the deterrent effect.     

Toxicity of leaf extract of yellow oleander Thevetia nerifolia on Tilapia

The usefulness of leaf extract as an ideal source of 'piscicide' in shrimp farming is described Leaf toxins are safe, eco-friendly and biodegradable. The fish Tilapia, Oreochromis mossambicus was exposed to the extract and the percentage of mortality at the end of 24,48, 72 and 96 hrs was recorded. The respective toxic range of aqueous, alcohol and acetone extracts of 24 hr LC50 and 96 hr LC50 values were found to be respectively 1118.79-330.30, 699.24-129.02 and 749.95-347.23 mg dry extract/litre for Oreochromis mossambicus. The LC50 values observed in different time periods in the fish exposed to aqueous extract were relatively high compared to the values obtained in acetone and alcohol extracts. Use of leaf extract, as piscicide in aquaculture farms is considered advantageous when viewed against the backdrop of using persistent chemicals.     

Interactive effects of salinity,temperature and polycyclic aromatic hydrocarbons on the survival and development rate of larvae of the mud crabRhithropanopeus harrisii

Zoeae of the mud crabRhithropanopeus harrisii (Gould) were exposed continuously throughout larval development to factorial combinations of salinity, temperature and specific aromatic hydrocarbon concentrations. Salinities and temperatures were 5, 15, or 25 and 20°, 25°, or 30°C, respectively. Either phenanthrene or naphthalene was tested separately at respective concentrations of 0, 100, 150 or 200 ppb and 0, 125, 250 or 500 ppb. Phenanthrene was much more toxic than naphthalene. Naphthalene was not acutely toxic at any physical factor combination-naphthalene concentration tested. Both compounds caused the highest mortality at low salinities. The time course of mortality due to phenanthrene exposure showed that ecdysis between the first and second zoeal stage was the most sensitive period for the larvae exposed to aqueous hydrocarbons. Phenanthrene-exposed larvae had a decreased development rate, but the naphthalene-exposed larvae developed faster than the controls.     

Acute toxicity levels and ethological responses of Channa striatus to fertilizer industrial wastewater

The present paper deals with the toxicity of fertilizer's industrial wastewater on snake head fish Channa striatus (Bloch) previously named as Ophiocephalus sp., at different concentrations viz., 20, 40, 60, 80 and 100 percent on the behavioural changes and mortality. The exposed fish showed hyperactivity viz., jumping, operculum movement, distance travelling, somersaulting at higher concentration such as 60, 80, and 100 percent within 48 hr. At lower concentrations such as 20 and 40 percent exposed fish showed hyperactivities viz., linear movement and eye movement within 48 hr. The LC50 values of industrial wastewater were also determined viz. 89, 75, 70 and 69 percent at different duration of exposure time i.e. 48, 72, 96 and 120 hr respectively. The obtained data revealed that LC50 value decreased with increase of exposure.     

Physiological effects of the detergent linear alkylbenzene sulphonate on blue mussel larvae (Mytilus edulis) in laboratory and mesocosm experiments

A series of laboratory (short-term exposure in small beakers) studies and a 19 d mesocosm (6 m³ polyethylene bags filled with fjord water) study were conducted on blue mussel, Mytilus edulis, larvae and plantigrades exposed to a concentration gradient of the detergent linear alkylbenzene sulphonate (LAS, 0 to 39 mg l⁻¹). LAS is increasingly found in nearshore environments receiving wastewater from urban treatment plants. The aims were to observe physiological effects on swimming, grazing and growth in the laboratory and effects on settling and population development at in situ conditions (in field mesocosms) in order to evaluate the damages on ciliated meroplankton caused by LAS. In the laboratory the larvae showed a 50% mortality at 3.8 mg LAS l⁻¹ after 96 h exposure whether or not food was provided. Additionally the swimming behaviour was affected at 0.8 mg LAS l⁻¹ (i.e. a more compact swimming track, a smaller diameter of the swimming tracks, and reduced swimming speed). The larval particle grazing was reduced 50% at 1.4 mg LAS l⁻¹. The specific growth rate of the larvae was reduced to half at 0.82 mg LAS l⁻¹ over 9 d. During the mesocosm experiment, the larval population showed a dramatic decrease in abundance within 2 d at concentrations as low as 0.08 mg LAS l⁻¹, both due to a significantly increased mortality, but also due to settling. The settling success was reduced at the same LAS concentration as that at which mortality was observed to increase significantly. In addition to reduced settling rate, the larvae showed delayed metamorphosis and reduced shell growth as a response to LAS. Our hypothesis that the larval ciliary apparatus, crucial for normal swimming, orientation, and settling behaviours and for particle uptake, was damaged due to LAS exposure is supported by our results. This is confirmed by the physiological data (grazing, growth) and in the direct video-based observations of larval performance (swimming) and provides a reasonable explanation for what was observed in the bags (abundance, settling, mortality). These physiological effects on blue mussel larvae/plantigrades occurred at LAS concentrations reported to occur in estuarine waters. Received: 15 January 1997 / Accepted: 12 February 1997     

天然提取物抗PM2.5诱导A549细胞凋亡的作用

采集北京城区大气可吸人颗粒物中的细颗粒物(PM25),用其对人肺腺癌A549细胞染毒,探讨PM25对细胞增殖的毒性和诱导细胞凋亡的作用,并且考察了加入不同浓度的红豆越橘提取物和竹叶提取物对其的抗性作用.实验采用MTT法检测细胞增殖作用,采用Annexi V-FITC/PI双染法和流式细胞仪检测细胞凋亡.结果显示:PM2...     

Sensitivity of veliger larvae of Mytilus edulis and mussel of various sizes to chlorination

The blue mussel Mytilus edulis is one of the dominant fouling organisms in cooling water systems. In this work, how veliger larvae and different size groups of the mussels responded against chlorine dosage was examined. Veliger larvae mortality was studied at different residual chlorine concentrations (0.05–0.5 mg L^?1), and it was found that a chlorine dose of 0.5 mg L^?1 is 4 times as effective as 0.05 mg L^?1 and twice as effective as 0.1 mg L^?1. Mortality of 100% for three size groups (1.4, 14, and 25 mm) and relative physiological activities of two size groups (14 and 25 mm) were observed. The exposure duration for 100% mortality of mussels decreased with the increasing residual chlorine concentration (0.1–4.0 mg L^?1). Mussel size was also found to be an important factor, considering that the continuation times for mussel mortality were 28 h for the 1.4 mm and 410 h for the 25 mm size groups. All size groups showed progressive reduction in physiological activities, such as oxygen consumption, foot activity, and byssus thread production with increasing chlorine dose (0.05–1.0 mg L^?1); the two data-sets were strongly correlated with each other. The results of this study should be of significance for optimizing the chlorine content, and minimize the environmental threat to industries where mussels are the dominant fouling organisms.     

Acute toxicity of ammonia to a freshwater teleost,Labeo bata larvae

Ammonia toxicity tests were performed with Labeo bata (bata) larvae of three different size groups. One hundred percent survival of larvae (500.0?±?4.0?mg) was recorded when exposed to ammonia concentrations of 1.0–13.56?mg?L^?1 at 96?h of exposure. Bata larvae exposed to ammonia concentrations of 15.8–25?mg?L^?1 showed 10–74% mortalities. The 96?h LC₅₀ value for 200 (±5), 250 (±2) and 500 (±4) mg bata larvae were 11.5, 16.8 and 22.5?mg?L^?1 un-ionised ammonia concentrations, respectively. When fish were exposed to different doses of ammonia, behavioural changes immediately occurred even at the lowest dose. At first, the fish became hyperexcitable, the skin darkened and they showed an increased ventilation frequency, fish behaviour became normal, 24?h after exposure. A 96?h LC₅₀ value of un-ionised ammonia showed direct relationship with the increasing size of bata larvae.     

芘污染对马氏珠母贝(Pinctada martensi)D型面盘幼虫发育的影响

多环芳烃(PAHs)是一类广泛存在于环境中的持久性有机污染物,大多具有潜在毒性、致癌性及致畸诱变作用。选取马氏珠母贝(Pinctada martensi)作为模式动物,研究芘对马氏珠母贝D型面盘幼虫发育的影响。将马氏珠母贝D型面盘幼虫暴露于不同浓度(2、4、8、16和32μg·L-1)芘(pyrene)中,在暴露后第12、24、36、48、60、72和84小时,分别测定其死亡率和畸形率,并观察形态学的变化。结果表明,芘对D型面盘幼虫的发育有显著影响,同一浓度组的死亡率与时间呈正相关。在2～32μg·L-1浓度范围内,不同暴露时间段,死亡率与浓度呈正相关。芘暴露对马氏珠母贝D型面盘幼虫的形态也有显著影响,随着芘浓度的增大幼虫畸形的比例增高,并呈现明显的剂量-效应关系,其中8和32μg·L-1浓度组的响应最敏感。同时,芘暴露对马氏珠母贝D型面盘幼虫的半数致死浓度(LC50)随着时间的推移逐渐降低,60h后趋于稳定,LC50值为43.50μg·L-1。研究结果表明,芘暴露能影响马氏珠母贝D型面盘幼虫的发育,并可能对其种群结构产生不利影响。     

Anti-implantation and anti-fertility potentials of Anethum graveolens L. extracts in rats

Ovarian hormones affected some enzymes in reproductive tissues. Previous studies revealed Anethum graveolens (dill) seed extract elevated ovarian hormones. In this study, we compared the effects of dill seed and leaf extracts on some enzymes activities and infertility potential. Female Wistar rats were divided into three groups of control, dill seed and dill leaf aqueous extracts treated groups. Experimental groups received 1 mL of 0.5 g kg^?1 of each extract orally for 25 days (five estrous cycles). Estradiol, progesterone, luteinizing hormone, and follicle stimulating hormone concentrations were determined. Uterus and ovaries were removed and their glucose-6-phosphate dehydrogenase, lactate dehydrogenase, and alkaline phosphatase activities were measured. Female rats of three groups were mated with untreated males. Fetuses were extracted in the 20th gestational day and their weights and crown rump lengths were measured. Anti-fertility and anti-implantation activities and fertility indices were calculated. Glucose-6-phosphate activity of dill seed treated group increased 1.6 times in the endometrium and 1.7 times in the myometrium. Progesterone concentration and lactate dehydrogenase activity of serum increased in the dill seed treated group compared to the control and dill leaf treated group. A significant decrease was observed in weights and crown rump lengths of fetuses, weights of placenta, and fertility index of the dill seed treated group compared to the control and dill leaf treated group, but its anti-implantation and anti-fertility indices increased. We suggested that high level of glucose-6-phosphate could entail increased oxidative stress in uterus and ovary. High lactate dehydrogenase activity in serum may affect cell membranes. Higher secretion of progesterone caused hormonal imbalance and produced estrous cycle irregularity. It was concluded that dill seed but not dill leaf extract could induce infertility in an animal model.     

Oceanographic habitat,growth and mortality of larval anchovy (<Emphasis Type="Italic">Engraulis encrasicolus</Emphasis>) in the northern Aegean Sea (eastern Mediterranean)

Data from two ichthyoplankton surveys carried out during June 1995 and June 1996 were used to study the broad scale distribution patterns of anchovy eggs and larvae over the northern Aegean Sea continental shelf and the regional/inter-annual variability in growth and mortality rates of larvae. Two major spawning grounds were identified. One in the east, located in the area influenced by the Samothraki gyre (SG), in which a large amount of enriched, modified Black Sea water (BSW) is entrapped and one in the west, associated with zooplankton-rich waters in the semi-enclosed Thermaikos gulf close to several river mouths. In the NE Aegean, anticyclonic gyres generated over the continental shelf and fed by the circulating stream of BSW (like the SG) may act as retention areas for larval anchovy. In the west, the high enclosure of the Thermaikos Gulf contributes to reducing offshore dispersal. Major changes were observed in egg and larval abundance as well as larval mortality between June 1995 and June 1996 in both the western and eastern part of the continental shelf. Mean abundance of eggs and early larvae was >5 times higher in 1996 than in 1995, when waters were significantly cooler, fresher and richer in mesozooplankton. Larval survival decreased from 79 to 69% day⁻¹ in the east and from 89 to 74% day⁻¹ in the west between 1995 and 1996. Hence increased egg production was coupled with higher larval mortality during June 1996. Furthermore, a highly significant positive relationship between larval mortality (Z) and mean egg abundance (A) emerged (Z = −0154 + 0.205 log[A], r ² = 0.96, n = 7) when data from this study and a similar study in the NW Mediterranean were regressed. Mean growth rate of anchovy larvae in the study area (∼0.5 mm day⁻¹) did not differ significantly between areas/years. A marked ontogenetic change was observed in the otolith size/recent otolith growth-on-fish size relationships, which exhibited significant inflection points at ∼6 mm formalin preserved length. This change seems to coincide with performance (e.g., catchability) and behavioral changes (e.g., onset of vertical migrations) in European anchovy associated with the development of the caudal fin (the flexion stage).     

Effect of caffeine, norfloxacin and nimesulide on heartbeat and VEGF expression of zebrafish larvae

The use of pharmaceuticals during pregnancy may causes abnormalities to the embryo. Sometime the drug also effect to the new born if the drug transferred through lactation. We have used zebrafish model to see the effect of some pharmaceuticals on embryos and larvae. Three drugs, caffeine, norfloxacin and nimesulide, were used for this study to see the effect mainly the hatching rate of eggs, heart beat rate and the vascular endothelial growth factor (VEGF) expression of the larvae. VEGF is an important signaling protein that involved generating the new blood vessels during embryonic development. We have used 10, 20, 50, 100 microg ml(-1) concentrations of all the drugs to see the effect. No significant mortality or malformations were observed in zebrafish embryos. Hatching was stared from 60 hr. In control group, 91% hatching rate was observed. Lowest hatching rate was observed using highest concentration of norfloxacin (100 microg ml(-1)) and nimesulide (100 microg ml(-1)) i.e. 55 and 56% respectively. In control group, 110 to 115 heart beat rate was counted per minute. Significantly higher heart beat was observed in caffeine treated group which is 125 to 140 min(-1) Lower heart beat was noted in nimesulide treated group which is 100 min(-1). We have tried to observe the possible effect of VEGF of the larvae by these three drugs. Expression of VEGF was very low in caffeine treated group. Almost no VGF expression was observe in 100 microg ml(-1) caffeine treated group. These studies suggest that there is a possibility that high dosage of caffeine can harm the unborn baby or new born babies, if the mothers use caffeine.     

Modelling the spatial population dynamics of the green oak leaf roller (Tortrix viridana) using density dependent competitive interactions: Effects of herbivore mortality and varying host-plant quality

Cyclic population dynamics of forest insects with periods of more than two generations have been discussed in relation to a variety of extrinsic and intrinsic forces. In the present study, we employed the selection pressure of density dependent competitive interactions according to Witting's equations (Witting, 2000) as driver for a discrete spatiotemporal model of the green oak leaf roller (Tortrix viridana). The model was successfully parameterised to rebuild the cyclic population dynamics of an empirical data set of a 30-year leaf roller monitoring in Russia. Our analysis focussed on the role of herbivore mortality and host plant food quality, which have a significant effect on T. viridana population dynamics. An additional egg or larvae mortality lowers population density and can lead to selection pressures that favour individuals with higher growth rate. This increased population growth rate can not only compensate the additional mortality, but also can lead to higher average moth abundances in subsequent generations. Furthermore, we analysed the effect of inter- and intraspecific variation in host plant quality on herbivore population dynamics and the spatial distribution of abundance and defoliation patterns. We found significant effects of the qualitative composition of a trees neighbourhood on the herbivore population of the respective tree. Also, the patchy damage patterns observable in reality have been reproduced by the present model. The applicability of the model approach and the putative genetic processes underlying Witting's model are discussed.     

Potential allelopathic effect of Pinus halepensis in the secondary succession: an experimental approach

Summary. Recent economic and social changes in north Mediterranean regions have led to an important rural depopulation. Consequently, meadows developed on abandoned agricultural lands (characterized by high species richness) undergo reforestation. These former fields are mainly colonized by Pinus halepensis Miller, which is known to synthetize a wide range of secondary metabolites, among these, some could influence plant succession through allelopathy. The allelopathic potential of P. halepensis, was tested against two target species (Lactuca sativa L. and Linum strictum L.) with aqueous extracts obtained from different organs (root and needle) taking into account the individual age (±10, ±30 and > 60 years old). Root and needle extracts affected differently germination and growth of the two target species, the responses varying with concentration of extracts, age and organs tested. The strongest inhibitory effect was observed on the germination and growth of L. strictum, exposed to needle extracts of young P. halepensis (±10 years old), and root extracts of older P. halepensis (> 30 years old). These extracts contained several phenolic acids (e.g. 4-hydroxybenzoic acid and p-coumaric acid), which are known as allelochemicals and their concentrations vary with age and organ tested. Hence, P. halepensis could influence secondary succession through the release of potential allelochemicals in the environment by leaf leachates or root exudates.     

Comparative study on the effect of chemicals on Alternaria blight in Indian mustard--a multi-location study in India

High severity of Altemaria blight disease is a major constraint in production of rapeseed-mustard in India. The aim of this study was to investigate the suppressive potential of chemicals viz., zinc sulphate, borax, sulphur, potash and calcium sulphate, aqueous extracts viz., Eucalyptus globosus (50 g l-1) leaf extract and garlic (Allium sativum) bulb (20 g l-1) extract, cow urine and bio-agents Trichoderma harzianum, Pseudomonas fluorescence in comparison with the recommended chemical fungicide (mancozeb), against foliar disease Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. and Coss] under five different geographical locations of India. Mancozeb recorded the lowest mean severity (leaf: 33.1%; pod: 26.3%) of Alternaria blight with efficacy of garlic bulb extract alone (leaf = 34.4%; pod = 27.3%) or in combination with cow urine (leaf = 34.2%; pod = 28.6%) being statistically at par with the recommended chemical fungicide. Chemicals also proved effective in reducing Alternaria blight severity on leaves and pods of Indian mustard (leaf = 36.3-37.9%; pod = 27.5-30.1%). The effective treatments besides providing significant reduction in disease severity also enabled increase in dry seed yield of the crop (mancozeb = 2052 kg ha-1; garlic = 2006 kg ha-1; control = 1561 kg ha-1).     

Upper temperature tolerances of Tellina tenuis and T. fabula

The upper lethal tolerances of Tellina tenuis da Costa and T. fabula Gmelin were studied under a variety of temperature regimes in which both short-term and long-term mortality were noted; these included steady temperatures, acclimation at a steady temperature then exposure to a steady tempeature, and acclimation at gradually increasing temperatures. T. tenuis alone was also tested for variation in mortality rate according to the date of collection or to the size (i.e., age) of the mollusc. The results suggested that T. tenuis was consistently more tolerant than T. fabula, and that the difference in tolerance was around 5 C°. Both species readily acclimated to higher temperatures after steady temperature acclimation, but not under a regime of gradually increasing temperature. There was no significant, variation in the mortality rate of T. tenuis with season or age. It is suggested that, since the difference in temperature tolerance is not reflected in their respective geographical distributions, there may be some other stage in their life cycle, e.g. the larvae, which is equally susceptible to temperature extremes. The difference in tolerance is, however, reflected in their respective littoral and sublittoral distributions.     

First-instar monarch larval growth and survival on milkweeds in southern California: effects of latex, leaf hairs and cardenolides

Growth rate and survival of first-instar larvae of Danaus plexippus, a milkweed specialist, depended on milkweed species, and was related to the amount of latex produced from wounds, leaf cardenolide concentrations and the presence of leaf hairs. Larval growth was more rapid and survival was higher on leaves of Asclepias californica with experimentally reduced latex, and this species has characteristically high latex, low- to mid-range cardenolide concentrations, and very hirsute leaves. Similarly, growth was higher on reduced latex leaves of both A. eriocarpa (a high latex/high cardenolide, hirsute species) and A. erosa (glabrous fleshy leaves, high latex/high cardenolides). There were no differences in either survival or growth rate between larvae on reduced latex or control leaves of the low latex/low cardenolide A. fascicularis with soft glabrous leaves and both survival and growth rate were higher on this species than the other species tested. Larval growth rates on leaves with reduced latex were similar among ten milkweed species tested to date but differed from growth rates on intact leaves suggesting that latex and possibly included cardenolides are both important in first-instar monarch larval growth, development and survival. We show for a range of ecologically important milkweeds that experiments on cut plant material (no latex outflow) lead to higher growth rates compared to intact plants. Such laboratory assays based on detached leaves will be misleading if the objective is to determine the impact of treatments such as Bt-maize pollen on monarchs on field plants.