Effects of different high constant and alternating temperatures on the development and prey consumption of <Emphasis Type="Italic">Dicyphus tamaninii</Emphasis> Wagner (Heteroptera,Miridae) with <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover (Homoptera,Aphididae) as prey

The present work aimed to study the effects of high constant and alternating temperatures on the development and prey consumption by Dicyphus tamaninii Wagner (Het., Miridae) with Aphis gossypii Glover (Hom., Aphididae) as prey.Results showed that the predator was able to successfully develop and reach the adult stage, on average, after 20.1 () and 20.6 () days at a temperature of 30 ± 1 °C with A. gossypii as prey. On the other hand, it was not able to develop at 35 ± 1 °C, here all N₁ instars used at the beginning of the experiments had died even before moulting to N₂ instar. At alternating temperatures of 25/15 ± 1 °C, the predator reached the adult stage 23.7 () and 23.5 () days after egg hatching, whereas when the temperatures were increased to 35/22 ± 1 °C, it took a significantly shorter period: 20.6 () and 20.9 () days. In general, the highest mortality occurred during the first two nymphal instars. The total percentage mortality during development from N₁ to adult stage was 30 % and 100 % at the constant temperatures 30 ± 1 °C and 35 ± 1 °C, respectively. At the alternating temperatures of 25/15 ± 1 °C, it was lowest with 16.5 %, while at 35/22 ± 1 °C, it was 20 %.The results of the experiments on prey consumption showed that an individual D. tamaninii consumed during its development to adult stage at 30 ± 1 °C an average of 442.2 (), 433.6 () aphids. At the constant temperature of 35 ± 1 °C, the average daily prey consumption started with 4 aphids and decreased continuously till it approached nil on the 9th day, where all predatory nymphs died. At the alternating temperatures of 25/15 ± 1 °C, the total prey consumption during development was, on average, 359.3 () and 297.0 () aphids, while at 35/22 ± 1 °C it was 348.5 () and 334.0 () aphids. The effect of the four temperatures on the prey consumption by D. tamaninii during the first 10 days after emergence was also studied. At a constant temperature of 30 ± 1 °C, a total of 446.4 () and 372.0 () aphids were consumed, compared to 40.6 () and 39.0 () at 35 ± 1 °C. At alternating temperatures of 25/15 ± 1 °C, the predatory adult consumed, on average, a total of 267.0 () and 207.0 () aphids. Increasing the temperature to 35/22 ± 1 °C resulted in a higher prey consumption by the adult predator, reaching 351.5 () and 267.7 () aphids over the same period.In conclusion, results indicated that D. tamaninii is a promising predator of the melon aphid at a temperature spectrum ranging from 15 ± 1 °C up to 35 ± 1 °C.     

Prey consumption preferences of<Emphasis Type="Italic"> Serangium parcesetosum</Emphasis> Sicard (Col., Coccinelidae) for different prey stages,species and parasitized prey

Serangium parcesetosum Sicard (Col., Coccinellidae) is considered one of the important predators of whiteflies. However, knowledge about its preferences for different prey stages, species and parasitized prey is still lacking in the literature. The present work investigated the preferences of S. parcesetosum for different stages of B. tabaci, different prey species and B. tabaci parasitized by Encarsia formosa Gahan (Hym., Aphelinidae) by prey consumption at different temperatures in the laboratory. Results showed that L₂ and L₄ predatory instars of S. parcesetosum preferred puparia to nymphs and eggs of Bemisia tabaci (Genn.) (Hom., Aleyrodidae). The mean daily prey consumption was 5.1–9.0, 4.5–6.2 and 3.6–4.3 by L₂ and 6.4–9.7, 5.5–8.5 and 2.5–7.5 by L₄ for puparia, nymphs and eggs, respectively. Adult females, however, indicated a significantly greater preference for both puparia and nymphs, consuming a daily mean of 6.4–7.5 puparia and 5.1–6.7 nymphs, but only 3.0–4.7 eggs. At 18 and 30 °C, all S. parcesetosum stages tested significantly preferred B. tabaci and Trialeurodes vaporariorum Westwood (Hom., Aleyrodidae) over the other three prey species offered. At both temperatures, all predatory stages preferred B. tabaci to T. vaporariorum, the L₂ instar at 18 °C, showing significantly more preference for B. tabaci than T. vaporariorum. In contrast, very few individuals were consumed from Aphis gossypii Glover (Hom., Aphididae), Frankliniella occidentalis (Pergande) (Thys., Thripidae) and Tetranychus urticae Koch (Acari, Tetranychidae). At 18 °C, a daily mean of 7.5–8.0, 6.6–9.0 and 6.7–8.1 B. tabaci as well as 5.3–6.4, 5.4–7.8 and 5.6–6.3 T. vaporariorum was consumed by L_2, L₄ and adult females, respectively, while at 30 °C, L₂, L₄ and adult females consumed a mean of 9.3, 8.8–9.7 and 8.3–9.7 B. tabaci/day as well as 8.3–9.0, 7.8–9.1 and 5.5–8.4 T. vaporariorum/day, respectively. S. parcesetosum L₂ and L₄ instars as well as adult females and males at both studied temperatures showed a significant tendency to avoid B. tabaci puparia after 5 days of parasitism by E. formosa and preferred to feed on unparasitized whiteflies. At 18 °C, the mean daily consumption was 8.7 and 0.2 (L₂), 11.1 and 0.6 (L₄), 12.1 and 1.0 () as well as 10.5 and 0.2 (), while at 30 °C the means were 15.9 and 0.5 (L₂), 19.8 and 1.0 (L₄), 18.9 and 1.2 () as well as 17.4 and 0.6 () from unparasitized and parasitized B. tabaci puparia, respectively.This paper is gratefully dedicated to Prof. Dr. W Schwenke on his 83rd birthday, 22 March 2004     

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.     

Studies on morphology and biology of immature stages of the predator Rhyzobius lophanthae Blaisdell (Col.: Coccinellidae)

Morphological characteristics of immature developmental stages of Rhyzobius lophanthae Blaisdell (Col.: Coccinellidae), predator of scale insects of the family Diaspididae (Homoptera), are described. Data about the morphology of eggs, the four larval instars, and the pupa is presented. Larval instars are described in more detail: size of head capsule, length of tibia, distribution of dorsal and lateral setae of abdomen segments for each larval instar is reported. Distribution of spiracles is also given. Study on the biology concerns the influence of prey on the duration of instar periods. The diaspidids Aspidiotus nerii and Aonidiella aurantii were used as food. The mean duration of the developmental period from egg to adult was 27.1 days, and no mortality was observed (0?%) when A. nerii was used as prey. The respective numbers when the prey was A. aurantii were 48.8 days and 84?%.     

Development, feeding and reproduction responses of Adalia fasciatopunctata revelierei(Mulsant) (Coleoptera: Coccinellidae) to Hyalopterus pruni(Geoffroy) (Homoptera: Aphididae)

This study was carried out to determine the development, survival and reproduction responses of Adalia fasciatopunctata revelierei (Mulsant) (Coleoptera: Coccinellidae) feeding on Hyalopterus pruni (Geoffroy) (Homoptera: Aphididae), using 20, 40, 80, 160 and 250 prey densities. All experiments were conducted at 25±1°C, 60±5% relative humidity, 16:8 light:dark under laboratory conditions. The average daily prey consumption of A. fasciatopunctata revelierei immatures and adults increased with increasing prey densities. Predation was not different for the larval stages at 80, 160 and 250 prey densities. The longevities of adult females were 35.67, 35.33, 49.00, 58.33 and 57.16 days when 20, 40, 80, 160 and 250 H. pruni were provided, respectively. The mean daily and total fecundity of A. fasciatopunctata revelierei increased with increasing prey densities. Females of A. fasciatopunctata revelierei feeding on H. pruni laid 89 eggs at 20 prey density and 301.67 eggs at 160 prey density. The search rate of females was higher than that of all larval instars; and the search rate of the fourth-instar larvae was higher than that of younger instars. Handling time decreased with development from larval stages to adult.     

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     

Development,life history characteristics and behaviour of mealybug predator, <Emphasis Type="Italic">Spalgis epius</Emphasis> (Westwood) (Lepidoptera: Lycaenidae) on <Emphasis Type="Italic">Planococcus citri</Emphasis> (Risso) (Homoptera: Pseudococcidae)

The development of immature stages, life history and behaviour of mealybug predator, Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) reared on mealybugs, Planococcus citri (Risso) (Homoptera: Pseudococcidae) was studied in the laboratory. Larvae of S. epius are a potential predator of different species of mealybugs in India. The predator completed its life cycle in 23.8 days with four larval instars. Mean incubation period of egg was 3.9 days. Mean duration of development of larval stages, prepupa and pupa was 9.4, 0.9 and 9.5 days, respectively. The first and last instar larvae measured 1.9 and 11.4 mm in length, respectively. Length and width were not significantly correlated in larvae. Head capsule width was not significantly correlated with larval length in any instar. The female-to-male sex ratio was 1.45:1. Adults were ready for mating one day after eclosion. The pairs remained in copula on an average of 61.3 min. The gravid female contained 74.6 eggs in the ovaries. Unfed butterflies (both males and females) lived 3–4 days, significantly shorter than those with access to water (6–7 days). The results of this study will be useful to utilize the predator as a biocontrol agent.     

Interception of photosynthetic photon flux density in a mangrove stand of <Emphasis Type="Italic">Kandelia candel</Emphasis> (L.) Druce

The canopy structure and interception of photosynthetic photon flux density (PPFD) in a 10-year-old Kandelia candel (L.) Druce stand were investigated before and after artificial defoliation. Leaf and wood areas for different layers were measured through area–weight relationships of subsamples. PPFD was measured at specified heights before and after leaf clipping. The leaf area index (LAI) and wood area index (WAI) were 4.501m²m^–2 and 1.412m²m^–2, respectively. There was a strong linear relationship between the cumulative wood area © and leaf area (F) densities from the top down to a given depth of the canopy, C = aF (r ² = 0.950), with a proportional constant a of 0.096 ± 0.008 (mean ± SE). The PPFD relative to that above the canopy (relative PPFD; I _R) at a given depth of the canopy was assumed to be given by the equation I _R = e^–(KCC+KFF ) = e^–KF , where the apparent light extinction coefficient K (= K _F + aK _C , where K _F and K _C are respectively the light extinction coefficient of leaves and woody organs) was calculated to be 0.502 ± 0.041 (mean ± SE) m^–2m² before leaf clipping. After leaf clipping, I _RC = e^–KCC is satisfied. As a result, the value of K _C was estimated to be 0.785 ± 0.046 (mean ± SE) m^–2m². The light extinction coefficient of leaves K _F was calculated to be 0.427m^–2m² using the indirect method, K _F = K – aK _C, and 0.432 ± 0.026 (mean ± SE) m^–2m² using the direct method, I _R/I _RC = e^–KFF . Of the total PPFD intercepted by the canopy, the fraction K _F/K due to leaves alone was estimated to be 85.0%–86.1% and the rest was contributed by woody organs.     

Neue Ergebnisse überBacillus thuringiensis var.tenebrionis unter besonderer Berücksichtigung seiner Wirkung auf den Kartoffelkäfer (Leptinotarsa decemlineata)

Especially younger larval stages (L₁...L₃) ofLeptinotarsa decemlineata are sensitive toB. thuringiensis var.tenebrionis (strain BI 256-82). The ingestion of parasporal crystals and spores by larvae caused feeding stop, gut paralysis, and final mortality by septicemia. Adults exposed to contaminated leaves stopped both feeding and egg-laying. The specific action on the gut epithelium is related to the crystal toxin. A non-specific effect caused by -exotoxin could be excluded as, contrary toB. t. var.thuringiensis, ourB. t. var.tenebrionis-strain does not produce this toxin. In contrast toB. t. var.tenebrionis, other strains of the same serotype (H 8a, 8b) belonging toB. t. var.morrisoni, as well as other strains ofB. t. (e. g. HD-1 of var.kurstaki) showed no activity againstL. decemlineata. — In field trials it was demonstrated that a dosage of 5×10¹⁴ spore equivalents per hectar is sufficent for an effective control of the Colorado beetle withB. t. var.tenebrionis. No side-effects on entomophageous insects, such asCoccinella septempunctata andChrysopa carnea, were noted.

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Neue Ergebnisse überBacillus thuringiensis var.tenebrionis unter besonderer Berücksichtigung seiner Wirkung auf den Kartoffelkäfer (Leptinotarsa decemlineata)

Zusammenfassung Besonders jüngere Larvenstadien (L₁...L₃) vonLeptinotarsa decemlineata reagieren empfindlich aufB. thuringiensis var.tenebrionis (Stamm BI 256-82). Die Applikation von parasporalen Kristallen und Sporen verursacht zunächst Fraßstop und Darmparalyse sowie schließlich den Tod der Larven durch Septikämie. Käfer stellen auf behandeltem Kartoffellaub Fraß und Eiablage ein. Die spezifische Wirkung auf das Darmepithel wird dem Kristalltoxin zugeschrieben. Eine unspezifsiche Wirkung durch -Exotoxin konnte ausgeschlossen werden: Unser Stamm vonB.t. var.tenebrionis produziert im Gegensatz zuB. t. var.thuringiensis kein derartiges Toxin. Im Gegensatz zuB. t. var.tenebrionis zeigten andere Stämme des gleichen Serotyps (H 8a, 8b), dieB. t. var.morrisoni angehören, ebenso wie andereB. t.-Stämme (z. B. HD-1 der var.kurstaki) gegenüberL. decemlineata keinerlei Wirksamkeit. — Feldversuche ergaben, daß eine Dosis von 5×10¹⁴ Sporenäquivalenten pro Hektar für eine wirksame Bekämpfung des Kartoffelkäfers mitB. t. var.tenebrionis ausreicht. Dabei wurden Entomophagen, wie z. B.Coccinella septempunctata undChrysopa carnea, nicht beeinträchtigt.

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Mit 5 Abbildungen

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Vortrag gehalten auf dem XVII. Internationalen Entomologenkongreß, 20.–26. August 1984 in Hamburg (Titel: A new isolate ofBacillus thuringiensis effective against Coleoptera).     

Effects of different neem preparations in comparison to synthetic insecticides on the whitefly parasitoid Encarsia sophia (Hymenoptera: Aphelinidae) and the predator Chrysoperla carnea (Neuroptera: Chrysopidae) on cotton under laboratory conditions

The contact and feeding toxicity of NeemAzal T/S (EID Parry, Chennai, India) to the parasitoid Encarsia sophia (Girault & Dodd) was compared with three synthetic insecticides (chlorpyriphos, endosulfan and triazophos) against immatures and adult emergence. NeemAzal T/S (1.0%) at lower dose (200 mg/l) did not cause any effect on the emergence of E. sophia adults, but there was a significant reduction in emergence at higher doses (800 mg/l). Also, it did not show contact toxicity to adults of E. sophia, but there was a significantly high feeding mortality in a dosage dependant manner, whereas chlorpyriphos, endosulfan and triazophos showed high toxicity both by contact and feeding method. Three neem preparations registered in India, NeemAzal T/S, Nimbecidine (T. Stains, Coimbatore) and Godrej Achook (Godrej Agrovet, Mumbai) were tested against egg and larval stages of Chrysoperla carnea (Stephens) at three dosages, using a synthetic insecticide, triazophos 40 EC (200 mg/l), for comparison under laboratory conditions. The three biorationals did not induce any adverse effect on the hatchability of C. carnea eggs. The mortality of the first instars of C. carnea was not affected by any of the azadirachtin enriched formulations; however, at higher dosage of 800 mg/l these neem based products resulted in increased mortality of the first and second instar larvae of C. carnea relative to the untreated controls. Whereas, triazophos induced very high mortality rates (85.0, 89.0 and 81.5%) of all the three larval instars. The neem based insecticides showed a dosage-dependant effect on the larval instars of C. carnea. Thus, these biorationals show that there is a potential to use them in an IPM system, being safe for natural enemies of B. tabaci in cotton.     

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.     

Gamma radiation sensitivity of larvae and adults of the red flour beetle, <Emphasis Type="Italic">Tribolium castaneum</Emphasis> Herbst

In this study, the susceptibility of larvae and adults of Tribolium castaneum (Herbst) to gamma radiation was investigated in the laboratory in Turkey. Gamma radiation was applied at 6 dose levels between 20 and 200Gy to 13–15day-old adults and at 5 dose levels between 20 and 180Gy to 18–20day-old larvae of T. castaneum. All experiments were performed in growth chambers maintained at 27±1°C and 70±5% r.h. The larvae proved to be the more susceptible stage, survival to the adult stage being prevented by exposure of the eggs to 100Gy; the adult stage was less susceptible. LD₅₀ and LD₉₉ values were determined as 19,75 and 42,97Gy for larvae and 33,21 and 64,50Gy for adult stage, respectively. It was concluded that 100Gy is the effective dose for both larval and adult stages.     

Keine Nebenwirkungen von Niempräparaten auf die aphidophagen PrädatorenChrysoperla carnea (Steph.) undCoccinella septempunctata L.

Zusammenfassung Die aus Niemsamen gewonnenen Präparate, AZT-Extrakt und AZT-Extrakt + Niemöl, führen weder bei Eiern, Larven und Imagines vonChrysoperla carned undCoccinella septempunctata zu erhöhter Mortalität noch zu Störungen der Fekundität. Nur bei direkter Benetzung der Larvenstadien im Labor kommt es zu einer Steigerung der Mortalität und der Ausprägung morphogenetischer Defekte in der Imaginalentwicklung. Unter den von der Arbeitsgruppe Pesticides and beneficial organisms der IOBC/WPRS vorgeschlagenen Testbedingungen sind die Präparate als nicht schädigend einzustufen.

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No side effects of neem extracts onChrysoperla carnea (Steph.) andCoccinella septempunctata L.

The application of AZT extract and AZT extract + neem oil does not harm eggs, larvae or adults ofChrysoperla carnea andCoccinella septempunctata. Mortality and fecundity are also not altered by neem-treatment. Only if the larvae are sprayed directly with the neem products in the laboratory, mortality increases and morphogenetic defects can be observed during adult development. Under the test conditions proposed by the IOBC/WPRS working group Pesticides and beneficial organisms the neem products can be considered to be harmless.

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Mit 6 Tabellen     

Antibiotic properties of the glucosinolates of Brassica oleracea var. acephala similarly affect generalist and specialist larvae of two lepidopteran pests

Glucosinolates may deter generalist insect feeding as their toxicity causes fitness damage, whereas insects specialized in brassicaceous plants may circumvent the toxic effect. By using no-choice leaf tests, we investigated whether larval development time, body weight, mortality and feeding rate of the generalist Mamestra brassicae (Lepidoptera, Noctuidae) and the specialist Pieris rapae (Lepidoptera, Pieridae), were affected by six genotypes of Brassica oleracea var. acephala, selected for having high or low concentration of sinigrin, glucoiberin (aliphatics) and glucobrassicin (indole). Two phenological plant stages were used. On young plants, M. brassicae most consumed the high sinigrin and low glucoiberin genotypes. Larvae weighed more on the high sinigrin plants. Development time took longer on the low glucoiberin genotype. On mature plants, consumption rate decreased on the high glucoiberin genotype. Larval weight decreased on the high sinigrin, glucoiberin and glucobrassicin genotypes, and development time increased with high glucobrassicin concentration. Pupal weight and mortality rate increased on mature plants, irrespective of the genotype. Pieris rapae fed most on young plants with high sinigrin, and larval weight increased on the high glucoiberin genotype. Mortality increased with low glucoiberin and low glucobrassicin. On mature plants, larval weight decreased with high sinigrin and glucoiberin. The high glucoiberin genotype was the less consumed and also induced a longer development time. High content of aliphatic glucosinolates offered mature plants significant antibiosis defence against both the lepidopterans, whereas the indole glucosinolate was marginally effective. Young plants were more consumed and increased larval weight likely because glucosinolate concentration was still not optimal.     

Entwicklung, Fraßleistung und Beutepräferenz vonHippodamia convergens Guer.-Men. (Col., Coccinellidae) mitThrips tabaci Lind. (Thys., Thripidae) sowie zwei Aphidenarten als Beute

Thrips tabaci Lind. is very difficult to control and thus one of the most important pests of leek in Europe. As an alternative to insecticides biological control may be carried out by making use of beneficial insects, the Coccinellidae being one of the most important predatory families. In the present study laboratory trials were carried out withHippodamia convergens Guer.-Men., one of the polyphagous representatives of the lady birds, to figure out the feeding activity, development and prey preference ofH. convergens against the onion thrips in comparison with two aphid species. H. convergens developed fully when fed exclusivelyT. tabaci larvae, although mortality was considerably higher and development took much longer. When fed thrips the complete development lasted 29,8 days on an average, the mortality reaching 88%. When offeredAcyrthosiphon pisum (Harris)H. convergens took only 24 days for development with a mortality of only 16%. Above all, the fourth larval instar and the pupa suffered from a very high mortality, reaching 45 and 50% respectively. WithA. pisum as a prey mortality decreased to only 6%. The duration of the pupal development was not affected by the prey species. The feeding activity ofH. convergens increased significantly during the development. The larvae of the second and fourth instar predated 28 and 170 thrips larvae respectively per day as a maximum. The adults achieved the highest feeding activity, predating more than 300 thrips larvae in 24 hours. When adding up the number of prey individuals per day for each developmental instar, the L₂ larvae predated more than 90 and the L₄ larvae more than 1000 thrips larvae. When offered thrips larvae andMyzus persicae (Sulz.) simultaneously, there was an increasing prey preference during the development ofH. convergens from first larval instar to adult. As to the last instars there was 20–25% less predation of thrips larvae compared to the aphids during 24 hours.     

Über Nahrungskreis und wirtschaftliche Bedeutung der Raubmilbe Agistemus exsertus Gonz. (Acari,Prostigmata)

Food range and economic importance of the predator mite, Agistemus exsertus Gonz. (Acari, Prostigmata) The predator miteAgistemus excertus fed on eggs ofTetranychus arabicus, crawlers of the scale insectChrysomphalus ficus, eggs of bothLipidosaphes baledi, andL. beckii, while it did not feed on eggs ofC. ficus and crawlers ofL. beckii. The predator developed and reproduced on all the four former prey types but at different rates. Eggs ofT. arabicus were the best food for quiker development, longer longevity and higher rate of reproductivity. These were followed by eggs ofL. baledi, crawlers ofC. ficus, and eggs ofL.beckii.     

Ein Vergleich vonChrysoperla carnea (Steph.)-Eiern mit und ohne Stielchen aus einer mit semisynthetischer Diät sowie aus einer mit Blattläusen ernährten Zucht im Hinblick auf einen Freilandeinsatz

Zusammenfassung In der vorliegenden Arbeit wurdenC. carnea-Eier mit und ohne Stielchen verglichen, die entweder aus einer mit semisynthetischer Diät oder aus einer mit Blattläusen ernährten Zucht stammten. Als wichtigste Parameter dienten dabei die Ermittlung der Schlupfrate der Larven sowie deren weitere Larval- und Pupalentwicklung. Die Versuche erfolgten in Klimaschränken unter definierten Bedingungen bei Einzelhaltung der Eier und der weiteren Entwicklungsstadien vonC. carnea in kleinen Petrischalen.Die Ergebnisse zeigten, daß die Schlupfrate der Larven aus beiden Varianten der Zucht Bionova, bei deren Eiern das Stielchen abgetrennt worden war, mit 60 bzw. 62% deutlich niedriger lag als bei denen der anderen Varianten mit 78, 84 und 86%. Die Larven, deren Eier aus der Institutszucht stammten und die mit Stiel belassen wurden, wiesen mit 19,9 Tagen eine signifikant längere Entwicklungsdauer auf als die der anderen Varianten. Die Larven derselben Zucht aus der Variante ohne Stiel benötigten 16,9 Tage zum Erreichen des Puppenstadiums, während die Larven der Varianten aus der Zucht Bionova sich nach 16,6, 16,1 und 15,8 Tagen verpuppten. Die höchste Mortalitätsrate von 50% konnte bei den Larven aus der Zucht Bionova festgestellt werden, deren Eier stiellos waren. Dagegen schwankte die Mortalität in den anderen Varianten zwischen 25,6 und 35,5%.Die Dauer der Puppenruhe war bei den Individuen aus der Zucht des Instituts mit 16,2 und 16,5 Tagen ungeachtet der verschiedenen Varianten signifikant länger als bei denen aus der Zucht Bionova. Die Puppen der Varianten aus der Zucht Bionova verblieben zwischen 13,5 und 13,8 Tage im Puppenstadium.

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A comparative study onChrysoperla carnea (Steph.)-eggs with and without stalk of a with semisynthetic diest and of a with aphids fed culture with regard to a field application

In the present studyChrysoperla carnea (Steph.) (Neuroptera, Chrysopidae)-eggs with and without stalk were compared. The eggs stem from stock breeds either fed with a semisynthetic diet (Bionova breed) or with aphids (Institute breed). The comparison is done with the use of the parameter hatching rate of the larvae and with parameters of the following larval and pupal development. The experiments were conducted in a climatic chamber under defined conditions. The individuums of the egg and the following development stages were each kept in little petri dishes.The results of the experiments exhibit that the hatching rate of those larvae which originate from both variants of the Bionova breed, where the eggs were seperated from the stalk, was clearly lower (60% and 62%) than that one of the other variants (78, 84 and 86%). The larvae, which stem from eggs with stalk maintained at the institute developed within 19.9 days which is significantly longer than the development time of the other variants. The larvae of the same breed but destalked required 16.9 days to reach the pupal stage. The development times of the 3 variants of the Bionova breed were 16.6, 16.1 and 15.8 days respectively.The mortality rate was highest (50%) for those larvae of the Bionova breed, which stem from eggs without stalk. In contrast to this the mortality of the other variants varied between 25.6 and 35.5%.The duration of the pupal stage for individuals that originate from the Institute breed was significantly longer (16.2 and 16.5 days) than that one for individuals of the Bionova breed 13.5 and 13.8 days). The other variants had no influence on the duration of the pupal stage.

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Mit einer Abbildung und 2 Tabellen     

Effects of a nursery CO2 enriched atmosphere on the germination and seedling morphology of two Mediterranean oaks with contrasting leaf habit

The use of an enriched CO₂ atmosphere in tree nurseries has been envisaged as a promising technique to increase productivity and to obtain seedlings with a higher root/shoot ratio, an essential trait to respond to water stress in Mediterranean-type ecosystems. In that framework, we have analyzed the effects of three levels of atmospheric CO₂ concentration (350, 500 and 700ppm) on the germination rate, growth and morphology of seedlings of two Mediterranean oaks used in reforestation programs: the evergreen Quercus ilex L. and the deciduous Quercus cerrioides Wilk. et Costa. CO₂ enrichment increased the germination rate of Q. cerrioides (from 70±7 to 81±3%) while it decreased that of Q. ilex (from 71±10 to 41±12%). Seedlings of both species increased approximately 60% their total biomass in response to CO₂ enrichment but at two different CO₂ concentrations: 500ppm for Q. cerrioides and 700ppm for Q. ilex. This increase in seedlings biomass was entirely due to an augmentation of root biomass. Considering germination and biomass partitioning, an enriched CO₂ atmosphere might not be appropriate for growing Mediterranean evergreen oaks, such as Q. ilex, since it reduces acorn germination and the only gains in root biomass occur at a high concentration (700ppm). On the other hand, a moderate CO₂ enrichment (500ppm) appears as a promising nursery technique to stimulate the germination, growth and root/shoot ratio of deciduous oaks, such as Q. cerrioides.     

Some developmental differences inEpinotia granitalis (Lepidoptera: Tortricidae) between two host tree species

To detect developmental differences inEpinotia granitalis in two host tree speciesCryptomeria japonica andChamaecyparis obtusa, the fourth or fifth instar larvae were collected daily from the two species located on the grounds of the National Forest Tree Breeding Center, from April 19 to May 9 in 1994 and April 18 to May 10 in 1995. Larvae ofE. granitalis collected fromC. obtusa had heavier body weight, developed to larger adults than those collected fromC. japonica, and mortality from the fourth or fifth instar larval stage to adults onC. obtusa was lower than that onC. japonica. All these facts suggest that larval performance onC. obtusa was higher than that onC. japonica.     

Über Einflüsse biophysikalischer und elektrischer Felder auf Lymantria monacha L.

Influences of biophysical and electrical fields on Lymantria monacha L. Caterpillar migrations, Faraday experiments, physical measurements Examinations of caterpillars migrations ofLymantria monacha in respect of biophysical food sources (food of normal zones and of zones of earth radiation) showed) — when compared with results of preceding mortality investigations — that larvae especially prefered food corresponding to certain developmental stages. Also the directions est west had a distinct influence on the caterpillars migrations. Influences of the migrations by direction as well as by the available food were different in the ranges investigated (normal zone, zone of earth radiation, metal zone). The result was a migration behaviour in the zone of earth radiation and in the metal zone like a reflected image when compared to the normal zone in respect to direction, in the metal zone partlly also to the food sources.The zone of earth radiation was especially frequented by L₁ and also as place of pupation.Experiment of rearing caterpillars ofLymantria monacha encaged under Faraday Conditions showed that restricting of entering the electrical fields was of unfavourable influence on first instar larvae, but of favourable on elder ones. This ascertained former results, that electrical-magnetical powers are promoting the vitality of first, but restrict this of last developmental stages.Measurements for indirect registration of biophysical fields by means of cathode ray oscillograph are described.

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Vortrag gehalten am Südtiroler Entomologentag in Dietenheim bei Bruneck am 21. September 1976.