Effect of GCSC-BtA biocide on abundance and diversity of some cabbage pests as well as their natural enemies in southeastern China

Journal of Plant Diseases and Protection - Effect of GCSC-BtA (Germany-China Scientific Cooperation — Bacillus thuringiensis — Abamectin) biocide on abundance and diversity of some...     

Investigations on side-effects of the mixed biocide GCSC-BtA on different predators of Plutella xylostella (L.) (Lep., Plutellidae) in southeastern China

The present paper deals with laboratory studies on side-effects of the mixed biocide GCSC-BtA on Plutella xylostella (L.) (Lep., Plutellidae) and its predators, e.g. Amblyseius longispinosus (Evans) (Acari, Phytoseiidae), Erigonidium graminicola (Sundvall) (Araneae, Linyphiidae), Orius similis Zheng (Het., Anthocoridae) and Coccinella septempunctata L.(Col., Coccinellidae), in comparison to the commercial insecticides, e.g. Abamectin, Tebufenozide, Dichlorvos, Cartap and Lambda-cyhalothrin.The results showed that GCSC-BtA was highly toxic to the 3^rd instar of P. xylostella with 91.18% mortality, followed by Cartap with 84.38%, Abamectin with 78.00%, Tebufenozide with 75.57%, Lambda-cyhalothrin with 63.75% and Dichlorvos with 50.86% mortality. On the other hand, GCSC-BtA was found to be comparatively less toxic to the predators, causing 31.11%, 13.33%, 11.54% and 6.00% mortalities in A. longispinosus, E. graminicola, O. similis and C. septempunctata, respectively. For comparison, the mortalities recorded for Abamectin, Tebufenozide, Dichlorvos, Cartap, Lambda-cyhalothrin were 72.94%, 55.55%, 70.00%, 53.26% and 98.85% in A. longispinosus, 46.51%, 55.10%, 60.00%, 46.00% and 73.68% in E. graminicola, 22.00%, 16.00%, 35.71%, 26.78% and 81.03% in O. similis, 15.55%, 19.64%, 28.00%, 16.66% and 41.79% in C. septempunctata, respectively.     

Attractiveness of three weed species to polyphagous predators and their influence on aphid populations in adjacent lettuce cultivations

The utilization of olfactory responses of predators and ­parasitoids to the allelochemicals emitted by phytophagous arthropods and their host plants is becoming more important in biological pest control. The effects of three weed ­species, i.e. wormwood Artemisia vulgaris L., tansy Tanacetum vulgare L. and stinging nettle Urtica dioica L., which were planted as accompanying vegetations into a lettuce field, were examined for the predatory species Coccinella septempunctata L., Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae), as well as for aphids during the summer of 2000. The presence of weeds significantly increased the density of adults and larvae of the predators on the lettuce plants in relation to the control (lettuce field without weeds). However, the differences remained smaller for eggs and pupae. C. septempunctata tended to be the most abundant species, followed by P. quatuordecimpunctata. Remarkable differences among the attractiveness levels of the weeds in the 3 treatments were not observed. The increased populations of predators were accompanied by significantly reduced infestation rates with aphids in the treatments in relation to the control. Myzus persicae Sulzer was in general the most abundant aphid species followed by Nasonovia ribisnigri Mosley and Macrosiphum euphorbiae Thomas. The results of the present study are discussed with respect to the management of agroecosystems and the use of weeds in biological control.     

Effect of GCSC-BtA biocide on population dynamics of cabbage pests and their natural enemies from fields in southeastern China

The present paper deals with the effect of the biocide GCSC-BtA on population dynamics of cabbage pests, i.e., Plutella xylostella (L.) (Lep., Plutellidae), Brevicoryne brassicae (L.) (Hom., Aphididae), Liriomyza sativae Blanch. (Dip., Agromyzidae), Phyllotreta vittata Fabric. (Col., Chrysomelidae) and their natural enemies, i.e., Apanteles plutellae Kurdj. (Hym., Braconidae), Erigonidium graminicola (Sundv.) (Araneida, Linyphiidae), Coccinella septempunctata L. (Col., Coccinellidae), in common head cabbage (Brassica oleracea var. capitata) fields in the southeastern China. The experiments were conducted at the experimental farm of Fujian Academy of Agricultural Sciences, Fuzhou, PR China in April–June, 2001.The results showed that, at the end of sampling, the pest populations of P. xylostella, B. brassicae and P. vittata reached averages of 39.7, 68.3 and 6.2 ind. / 30 plants in the plot treated with GCSC-BtA, which were about 1.5, 11 and 0.7 times lower than those treated with methomyl, respectively. In contrast, the natural enemy populations were, on average, 23.5 ind./30 plants for A. plutellae, 24.6 ind./30 plants for E. graminicol and 12.2 ind./30 plants for C. septempunctata in the plot treated with GCSC-BtA, about 6, 5 and 3 times higher than for those treated with methomyl, respectively. The GCSC-BtA biocide demonstrated greater effectiveness in controlling the cabbage pests, e.g., P. xylostella, B. brassicae and P. vittata, having final decreasing ratios of 83.60, 97.05 and 53.67% compared to 57.63, 64.89 and 30.88% with the methomyl insecticide. However, it was less toxic to natural enemies, e.g., A. plutellae, E. graminicola and C. septempunctata, final decreasing ratios being 47.68, 17.84, 27.81%, than methomyl, with 90.94, 80.80, 74.55%, in comparison to the populations in the control plots, respectively. So, because of the low toxicity of GCSC-BtA to the natural enemies, it is recommended that, on one hand, its application should be carried out after mass migration of the pests to the fields, on the other hand, the alternative agent GCSC-BtA should be used with the aim of minimizing the harmfulness to the natural enemies in the whole program of integrated pest management in cabbage fields.     

Attractiveness of three weed species to polyphagous predators and their influence on aphid populations in adjacent lettuce cultivations

The utilization of olfactory responses of predators and ­parasitoids to the allelochemicals emitted by phytophagous arthropods and their host plants is becoming more important in biological pest control. The effects of three weed ­species, i.?e. wormwood Artemisia vulgaris L., tansy Tanacetum vulgare L. and stinging nettle Urtica dioica L., which were planted as accompanying vegetations into a lettuce field, were examined for the predatory species Coccinella septempunctata L., Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae), as well as for aphids during the summer of 2000. The presence of weeds significantly increased the density of adults and larvae of the predators on the lettuce plants in relation to the control (lettuce field without weeds). However, the differences remained smaller for eggs and pupae. C. septempunctata tended to be the most abundant species, followed by P. quatuordecimpunctata. Remarkable differences among the attractiveness levels of the weeds in the 3 treatments were not observed. The increased populations of predators were accompanied by significantly reduced infestation rates with aphids in the treatments in relation to the control. Myzus persicae Sulzer was in general the most abundant aphid species followed by Nasonovia ribisnigri Mosley and Macrosiphum euphorbiae Thomas. The results of the present study are discussed with respect to the management of agroecosystems and the use of weeds in biological control.     

Effect of GCSC-BtA biocide on population dynamics of cabbage pests and their natural enemies from fields in southeastern China

The present paper deals with the effect of the biocide GCSC-BtA on population dynamics of cabbage pests, i.?e., Plutella xylostella (L.) (Lep., Plutellidae), Brevicoryne brassicae (L.) (Hom., Aphididae), Liriomyza sativae Blanch. (Dip., Agromyzidae), Phyllotreta vittata Fabric. (Col., Chrysomelidae) and their natural enemies, i.?e., Apanteles plutellae Kurdj. (Hym., Braconidae), Erigonidium graminicola (Sundv.) (Araneida, Linyphiidae), Coccinella septempunctata L. (Col., Coccinellidae), in common head cabbage (Brassica oleracea var. capitata) fields in the southeastern China. The experiments were conducted at the experimental farm of Fujian Academy of Agricultural Sciences, Fuzhou, PR China in April?–?June, 2001. The results showed that, at the end of sampling, the pest populations of P. xylostella, B. brassicae and P. vittata reached averages of 39.7, 68.3 and 6.2 ind. / 30 plants in the plot treated with GCSC-BtA, which were about 1.5, 11 and 0.7 times lower than those treated with methomyl, respectively. In contrast, the natural enemy populations were, on average, 23.5 ind./30 plants for A. plutellae, 24.6 ind./30 plants for E. graminicol and 12.2 ind./30 plants for C. septempunctata in the plot treated with GCSC-BtA, about 6, 5 and 3 times higher than for those treated with methomyl, respectively. The GCSC-BtA biocide demonstrated greater effectiveness in controlling the cabbage pests, e.?g., P. xylostella, B. brassicae and P. vittata, having final decreasing ratios of 83.60, 97.05 and 53.67?% compared to 57.63, 64.89 and 30.88?% with the methomyl insecticide. However, it was less toxic to natural enemies, e.?g., A. plutellae, E. graminicola and C. septempunctata, final decreasing ratios being 47.68, 17.84, 27.81?%, than methomyl, with 90.94, 80.80, 74.55?%, in comparison to the populations in the control plots, respectively. So, because of the low toxicity of GCSC-BtA to the natural enemies, it is recommended that, on one hand, its application should be carried out after mass migration of the pests to the fields, on the other hand, the alternative agent GCSC-BtA should be used with the aim of minimizing the harmfulness to the natural enemies in the whole program of integrated pest management in cabbage fields.     

Olfactory reactions ofCryptolaemus montrouzieri Mulsant (Col., Coccinellidae) andChrysoperla carnea (Stephens) (Neur., Chrysopidae) in relation to period of starvation

In a laboratory study, it was tried to measure the extent of olfactory responses of two predators namelyCryptolaemus montrouzieri Mulsant andChrysoperla carnea (Stephens) to their respective preys at varied levels of their starvation. Results indicated that both the predators, irrespective of their developmenta stage, oriented more positively to their preys odour when they were deprived of food for certain period of time than they did so when tested directly without subjecting them to starvation. The first, second, third and fourth instar larvae and adults ofC. montrouzieri showed maximum response at 4 h, 8 h, 12 h, 12 h and 24 h of starvation, respectively. Similarly, the larvae ofC. carnea responded maximum with 4 h, 8 h and 12 h of hunger in first, second and third instar, respectively. However it was also evident that the continued starvation for more than certain ideal period affected the predators olfactory orientation negatively. But the adults ofC. montrouzieri differed slightly in their behavior as they could respond positively for comparatively longer period of starvation.

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Zusammenfassung In Laborversuchen wurde das Ausmaß der olfaktorischen Reaktionen der beiden PrädatorenCryptolaemus montrouzieri Mulsant undChrysoperla carnea (Stephens) auf deren BeuteinsektenPlanococcus citri Risso respektiveAcyrthosiphon pisum (Harris) und in Abhängigkeit von der Dauer einer vorangegangenen Hungerperiode, namentlich 2, 4, 8, 12, 16, 20 und 24 Stunden, ermittelt. Wie die Ergebnisse belegen, reagieren beide Prädatoren-Arten unabhängig vom jeweiligen Entwicklungsstadium stärker auf den Geruch ihrer Beute, wenn sie zuvor eine bestimmte Zeit unter Ausschluß von Nahrung gehalten worden waren. Dabei zeigte sich bei den Larven beider Arten ein typischer Verlauf der Attraktivität durch die Beute, nach dem diese mit zunehmender Dauer der Hungerperiode zunächst zunahm, um nach einem Maximum wieder deutlich abzufallen. Dieser Verlauf erwies sich für die einzelnen Larvenstadien als unterschiedlich. So wurde fürC. montrouzieri das Maximum bei den L₁-Larven mit durchschnittlich 9,33 von 15 durch die Beute angelockten Individuen bereits nach einer Hungerperiode von 4 h erreicht, für die L₂ jedoch mit 9,50 Individuen erst nach 8 und für die L₃ sowie L₄ erst nach 12 h mit 8,83 respektive 9,17 Individuen. Lediglich bei denC. montrouzieri-Adulten war eine kontinuierliche Zunahme der Attraktivität der Beute während des Untersuchungszeitraums von 24 h festzustellen, wobei das Maximum bei 10,00 Individuen lag. Analog wurde für das ersteC. carnea-Larvenstadium bei einer 4stündigen Hungerperiode mit 55,5% attrahierten Individuen das Maximum erreicht, wohingegen das zweite Stadium mit 61,1% bei der 8- und das dritte mit 65,5% bei der 12stündigen Hungerperiode die maximale Attraktion durch die Beute aufwies.

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With one table and one figure     

德国植物保护方面重要的法律法规

植物是地球表面绿色覆盖的基本单位，植物需要保护，植物保护法律法规为植物保护提供了保证。本文简要又全面地介绍了现行适用的德国植物保护法以及和植物保护有关的法律法规，以期在我国的相关法律法规的建设中起到参考作用。     

Insecticidal activity and antifeedant effect of a new type biocide GCSC-BtA against Plutella xylostella L. (Lep., Plutellidae)

Insecticidal activity and antifeedant effect of a new type biocide GCSC-BtA and its two reactants Bacillus thuringiensis (B.t.) crystal and Abamectin against third instar larvae of Plutella xylostella L. (Lep., Plutellidae) were investigated using bioassays. GCSC-BtA showed significantly higher toxicity to P. xylostella with LC₅₀ of 0.021 mg/ml than B.t. crystal with 0.060 mg/ml and Abamectin with 0.139 mg/ml in leaf-dip bioassay. Net leaf-dip test gave LC₅₀s of 0.073, 0.071 and 0.670 mg/ml for GCSC-BtA, B.t. crystal and Abamectin, respectively. The significant differences of the biocide toxicities between leaf-dip and net leaf-dip methods showed the potential of net leaf-dip method for separating ingestion and contact poisons. Variation in toxicity of the biocide and two reactants in net leaf-dip method and in mortality in topical application bioassay showed that GCSC-BtA possessed a combination of strong stomach as well as contact poison property higher than B.t. or Abamectin. GCSC-BtA indicated no fumigant and systemic toxicities, which the two reactants lacked. In the antifeedant bioassay, GCSC-BtA acted as a strong antifeedant to the larvae of P. xylostella. Leaf consumption by the larvae after GCSC-BtA treatment was 0.04–0.60 mm² with a concentration range of 0.04–4.00 mg/ml, which was lower than 0.26–1.02 and 0.04–6.47 mm² for B.t. crystal and Abamectin, respectively. DC₅₀ (concentration resulting in a deterrence index of 50%) value for GCSC-BtA was 0.089 mg/ml, which was also significantly lower than 0.275 and 0.736 mg/ml for B.t. crystal and Abamectin, respectively.     

The potential use of different predatory bug species in the biological control of<Emphasis Type="Italic"> Frankliniella occidentalis</Emphasis> (Pergande) (Thysanoptera: Thripidae)

In the present study, the suitability of different predatory bug species, such as Dicyphus tamaninii Wagner, Macrolophus pygmaeus (Rambur), Orius albidipennis Reuter, Orius majusculus Reuter and Orius sauteri Poppius, for the biological control of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were investigated. Development of the predatory bug species, their reproduction as well as their daily and total prey consumption over a 18-day period with F. occidentalis larvae or various stages of Tetranychus urticae Koch (Acari: Tetranychidae) individuals as prey species were studied during the experiments in the laboratory. In further experiments, the efficiency of D. tamaninii, M. pygmaeus, O. albidipennis and O. majusculus in controlling F. occidentalis under glasshouse conditions was investigated. Results showed that all the predators could develop under the experimental conditions with either F. occidentalis larvae or different stages of T. urticae as prey. When F. occidentalis larvae were offered as prey, the shortest duration of development was observed for O. albidipennis with a mean of 17.7 days, while D. tamaninii took the longest to develop with a mean of 36.3 days. With different stages of T. urticae as prey, the duration of development ranged from 19.3 days in O. albidipennis to 42.9 days in M. pygmaeus. Mean daily fecundity ranged from 0.8 eggs/female for O. majusculus to 2.2 eggs/female for O. sauteri with F. occidentalis larvae as prey and from 0.6, O. majusculus, to 2.3 eggs/female/day, O. sauteri, when different stages of T. urticae were offered as prey. Over the 18-day reproduction period, O. sauteri was the most fecund predatory species, laying a mean total of 31.6 and 31.3 eggs/female with F. occidentalis and T. urticae as prey, respectively. Daily consumption from F. occidentalis larvae ranged between 5.5 individuals consumed per day by O. majusculus and 29.1, by O. sauteri. When different stages of T. urticae were offered as prey, maximal consumption was observed in D. tamaninii with a mean of 29.0 individuals/day, while O. albidipennis consumed the least with an average of 8.1 preys/day. Over the 18-day prey consumption period, D. tamaninii consumed the highest mean number of 422.8 F. occidentalis larvae, while O. majusculus only consumed 98.8 larvae. Also, D. tamaninii had the maximum consumption of different stages of T. urticae with a mean of 522.4, while M. pygmaeus and O. albidipennis consumed the least, with an average of 146.1 and 146.0, respectively. The predatory bugs D. tamaninii, M. pygmaeus, O. albidipennis and O. majusculus significantly reduced the density of F. occidentalis on hybrids of Euphorbia milii, Serissa foetida and Saintpaulia ionantha in the glasshouse, which confirms their efficiency against this pest on different hosts under controlled climatic conditions.