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1.
Zusammenfassung Von 1974–1980 wurden in der Umgebung von Zürich (Schweiz) Beobachtungen über die Nahrungsökologie von Spinnen durchgeführt. Die Resultate lassen sich wie folgt zusammenfassen: Sämtliche untersuchten Spinnenarten fraßen ausschließlich an Evertebraten (Insecta, Arachnida, Isopoda, Myriapoda, Lumbricidae). Bei den meisten untersuchten Spinnen bestand die Nahrung zu>90% aus Insekten. Kleine Fluginsekten (Dipteren, Blattläuse) stellen für zahlreiche Spinnen der Vegetationsschicht die Hauptnahrungsquelle dar. Kleine, weichhäutige Insekten (Collembolen, Blattläuse, Dipteren) sind die Nahrungsbasis der dominanten Spinnen der Bodenoberfläche. Ein vom Durchschnitt abweichendes Beutespektrum besitzen die ArtenArgiope bruennichi (Prädator von Heuschrecken u. Bienen),Xysticus cristatus (epigäisch: Prädator von Ameisen u. Spinnen),Achaearanea riparia (Prädator von Amesien u. Käfern),Coelotes terrestris (Prädator von Käfern),Pholcus phalangioides (Prädator von Asseln, Spinnen, Opilioniden etc.). Die untersuchten Spinnenarten weisen unterschiedlich breite Nahrungsspektren auf. So ist beispielsweise das Nahrungsspektrum bei den Trichterspinnen der GattungAgelena weit aufgefächert (polyphag). Im Vergleich dazu hat die TrichterspinneC. terrestris ein enges Beutespektrum (oligophag). Während bei den meisten Spinnenarten die Beutegröße der Räubergröße angepaßt ist (Beutegröße Räubergröße), erlegen einige Spinnenarten (v. a. Familien Thomisidae und Theridiidae) gelegentlich Beutetiere, die größer als sie selber sind. Die Spinnen sind überwiegend Sekundärkonsumenten innerhalb von Herbivoren-Nahrungsketten. Die auf Waldböden lebenden Wolfspinnen greifen zusätzlich auch in Detritus-Nahrungsketten ein. In Flußuferbiotopen ernähren sich Skorpionsfliegen (GattungPanorpa) häufig von Beutetieren in Spinnennetzen (Nahrungsdiebstahl).
Field studies on the feeding ecology of spiders: Observations in the region of Zurich (Switzerland)
The results of studies on the feeding ecology of spiders from 1974–1980 can be summed up as follows: All species of spiders examined fed exclusively on evertebrates (Insecta, Arachnida, Isopoda, Myriapoda, Lumbricidae). In most cases, more than 90% of the food consisted of insects.Numerous spiders living in the vegetation stratum feed mainly on small flying insects, such as Diptera and aphids. The same is true for the dominant spiders living on the surface of the soil, though their prey spectrum is supplemented by Collembola and apterous aphids. Thus in the average prey spectrum of spiders small insects with a soft cuticle dominate. Exceptions are found withArgiope bruennichi, a predator of grasshoppers and bees,Agelena spp. feeding mainly on relatively large insects,Xysticus cristatus, which, when hunting on the ground, preys on ants and spiders,Achaearanea riparia, preying on ants and beetles,Coelotes terrestris, a specialized predator of beetles, andPholcus phalangioides, preying on wood-lice, spiders, opilionides etc. The prey spectra of the spider species examined vary considerably in breadth. So the food spectrum of the funnel-web spiders of the polyphagous genusAgelena is large compared to that of the oligophagousC. terrestris. Whereas in most spider species the size of their prey is relatively small or only reaches the size of the predator (size of prey size of predator), some species, mainly of Thomisidae and Theridiidae, prey at times upon prey larger than they are.Spiders are secondary consumers belonging predominantly to herbivor food chains. Wolf spiders living on forest grounds intervene also in detritus food chains. Scorpionflies (genusPanorpa) often feed on prey animals in spider webs (food robbery).

Ausgeführt mit Unterstützung durch den Schweizerischen Nationalfonds zur Förderung der Wissenschaftlichen Forschung.  相似文献   

2.
The most important literature on the ecological importance of spiders for forest ecosystems was compiled and analyzed. Forest spiders normally live in densities of 50 to 200 individuals/m2 and prey, at least in Europe, predominantly on small soft-bodied insects (Diptera and Collembola mainly). However, bigger insects, including various forest pests, are also found in their prey. According to the present stand of knowledge the spiders of the soil surface seem to be important insect predators, whereas the ecological importance of spiders living on the trees is still controversial.  相似文献   

3.
大腹圆蛛(Araneus ventricosus)在吉林省2年完成1代,跨3个年度,以1-2龄和6-7龄若蛛越冬。该蛛除卵期及1、2龄蛛外,其它龄态的若、成蛛均张网捕食生活。该蛛喜居有光的栖境,在林缘、林窗处、路旁处结圆形垂直网,昼伏夜出,在小雨条件下可以正常活动。大腹圆蛛对小型猎物可直接取食,对中、大型猎物,需缠绕成束的捕获丝缚住再取食。在林间大腹圆蛛可取食多种蛾和叶蜂成虫,包括兴安落叶松鞘蛾、落叶松毛虫、黄褐幕枯叶蛾、舞毒蛾、栎毒蛾、松皮小卷蛾、松廮小卷蛾、伊藤厚丝叶蜂和落叶松叶蜂等多种落叶松害虫,是一种有效的害虫天敌。  相似文献   

4.
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5.
Seasonal dynamics of the whitebacked planthopper (WBPH), Sogatella furcifera; its major predators (Cyrtorhinus lividipennis, Microvelia horvathi, Theridion octomaculatum, Oedothorax insecticeps, and Pardosa pseudoannulata) and parasitoids (Anagrus spp.); and collembolans and chironomids were investigated in organically manured (OM) plots as well as in chemically fertilized (CF) plots of rice in Hangzhou between June and September 2001. Predation and parasitism of WBPH eggs were also surveyed. Among these arthropods, only the abundances of M. horvathi and collembolans were clearly modified due to manure use, with density of the former being significantly decreased around 61 days after transplantation (DAT) and the latter significantly increased 21–28 DAT. Density of WBPH (nymphs and adults) was relatively low before 21 DAT, but it increased rapidly thereafter and peaked between 28 and 35 DAT in both OM and CF plots. Predation on WBPH eggs increased significantly around 47 DAT due to the manure use, and parasitism on eggs also increased persistently between 17 and 47 DAT. These results suggested that biological control of WBPH could be potentially enhanced by manure use in two approaches, i.e., by increasing alternative prey (collembolans) of WBPH predators (particularly spiders) around 21 DAT or earlier when WBPH are scarce and by mediating plant quality in a way that favors natural enemies of WBPH eggs.  相似文献   

6.
In olive orchards, which are very common in the Mediterranean region, cover crops are becoming increasingly used to counter problems of erosion. Although such plant covers can provide food and shelter for beneficial insects, mites, and spiders, they may also attract pests. In order to determine their relationships with the main pests in olive orchards, an analysis was made of adult population levels and damage caused in five olive-cultivation zones, in olive orchards with cereal-crop covers and in olive orchards with conventional tillage. The effects of the cereal cover crops on insect pest populations were different and in some cases in opposite direction. Thus cereal cover crops had no impact on the different studied pests, including all those that spend part of their development cycle in the soil, such as Bactrocera oleae, Prays oleae, or Otiorrhynchus cribicollis. However, under certain conditions some pests did show an increase in abundance. Diverse trophic relationships should be investigated in this agroecosystem in future studies in order to develop appropriate crop-management policies.  相似文献   

7.
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.  相似文献   

8.
Generalist arthropod predators are potential drivers of population dynamics in a wide variety of ecosystems but their feeding habits are often difficult to reveal as they are small, mobile, and live among dense vegetation or in soils. DNA-based gut-content analysis is a powerful tool that enables studies on arthropod predator–prey interactions. We studied lycosid spiders (Pardosa spp.) in agroecosystems to see if they consumed cereal aphids (Rhopalosiphum padi) and Collembolans at random, i.e., in proportion to their abundance in the field. We also tested if consumption of the target prey items was affected by the presence of alternative food. Spiders were captured in farmers’ fields and their gut-contents screened by PCR with R. padi and Collembola primers. On all sampling occasions, concurrent assessments of total prey availability were carried out. Spider predation rates on R. padi always exceeded 50 %. Spiders also tested positive for Collembola but to a lower and more varying degree. In general, Pardosa did not consume R. padi and Collembolans in relation to their abundance in the field. Aphid predation was much higher than expected whereas consumption of Collembolans was considerably lower. The presence of alternative prey influenced consumption of the aphid. It was concluded that prey consumption by Pardosa spiders generally cannot be assumed to simply mirror prey availability. The spatial distribution of the target prey needs to be considered as well as the abundance, composition, and nutritional content of potential alternative food items.  相似文献   

9.
From January 2001 to December 2004, the investigation on the species of insect pests and diseases in Torreya grandis Merrillii was conducted and integrated control technologies of the main insect pests and diseases were studied in Zhuji, Shaoxin, Shenzhou, Dongyang, and Jiande counties of Zhejiang Province. Via field survey, a system of regular observations, 55 species of insect pests belonging to 9 orders and 29 families, and 4 species of diseases were recorded. Among them, Lepteucosma torreyae and Macrolygus torreyae were found to be new species. The biological characteristics of the major insect pests and diseases, such as Rhyncaphytoptus abiesis, Helicobasidium compacum, Erwinia carotovora, Chlorella sp., Macrolygus torreyae, and Lepteucosma torreyae, were primarily recorded, and their outbreaks and epidemics were researched. The forecasting method for Lepteucosma torreyae was established. Based on strengthening cultivation and management, integrated control measures were put forward including physical, biologic and chemical methods. Medications with higher effect and lower toxicity were screened by comparing the effect of different pesticide treatments. __________ Translated from Journal of Zhejiang Forestry College, 2005, 22(5): 545–552 [译自: 浙江林学院学报, 2005, 22(5): 545–552]  相似文献   

10.
Exploiting the principles of biological control of crop pests is an important management strategy for the resource-poor smallholder farmers of the tropics. The effects of nine hedgerow species on the abundance of major insect pests of beans and maize, and predatory/parasitic-arthropods were monitored over two cropping seasons and the intervening dry period. The tree/shrub species evaluated were Gliricidia sepium, Grevillea robusta, Senna siamea, Senna spectabilis, Flemingea congesta, Croton megalocarpus, Morus alba, Calliandra calothyrsus and Lantana camara. Arthropod abundance was monitored through counts of infested plants and using yellow pan and pitfall traps. Beanfly (Ophiomyia spp.) infestation was significantly higher in the presence of hedgerows (35%) than in their absence (25%). Hedgerows did not influence aphid (Aphis fabae) infestation of beans. In contrast, maize associated with hedgerows experienced significantly lower stalk borer (Busseola fusca and Chilo spp.) and aphid (Rhophalosiphum maidis) infestations than pure maize, the margin of difference being 13% and 11% respectively for the two pests. Ladybird beetles closely followed their prey, aphids, with significantly higher catches in sole cropped-plots than in hedgerow-plots and away from hedgerows. Activity of wasps was significantly greater close to hedgerows than away from them. Spider catches during maize season were 77% greater in the presence of hedgerows than in their absence, but catches during other seasons were similar between the two cropping systems. Differences among hedgerow species were not significant for most of the arthropods monitored, except that beanfly infestation was greater with Gliricidia hedgerows. The study indicates that the effect of hedgerows on pest infestations of crops and their role as refugia for predators cannot be generalized but depends on the specific arthropods.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

11.
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 L2, 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  相似文献   

12.
Monitoring populations of pests and their natural enemies under different management situations and seasonal weather parameters provides extremely useful information for taking preventive measures against pest outbreaks. The abundance, spatial and temporal distributions of herbivorous insects and arthropod natural enemies on Alnus species were monitored at four sites in Kabale district, Uganda between June 1999 and August 2000. Chewing insects, dominated by Coleoptera (75%), constituted the majority of insect herbivores sampled. Dominant and potentially serious pests of Alnus included Apion globulipenne, an unidentified Chrysomelidae (Coleopt. 27), Phymateus viridipes, Coloborrtics corticina and a Cacopsylla species (Homoptera: Psyllidae). Spiders were the predominant natural enemies accounting for 64% of the total natural enemies encountered, followed by parasitic Hymenoptera (30%). There were marked spatial and temporal variations in arthropod abundance. Among sites, mean abundance of total insect herbivores and total natural enemies on A. acuminata over 15 months ranged from 3.8–8.5 and 3.3–4.7 individuals per 1-m branch length respectively. Over the same period, mean number of total insect herbivores and total natural enemies on A. nepalensis that was studied at only one site were 11.9 herbivores and 4.2 natural enemies per 1-m branch length. Populations of most insect orders increased in the wet season although the greatest herbivore abundance was evident in the dry season. Further studies are necessary on the impact and management strategies of the potentially important insect pests and natural enemies on Alnus.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

13.
Dipterous flies are considered among the most important pests for man and domestic animals health. The efficacy of four insect growth regulators on dipterous larvae and mites inhabiting dung of two farm anaimals (buffalo and sheep) are compared. Also, their effectiveness on the predacious mites are discussed. Data indicated that the toxicity of the four tested IGRs, i. e., Dimilin, XRD, IKI and CME, to the dung survivors (dipterous larvae and mites) differed according to the source of dung and the occurrence of survivors themselves. In buffalo dung, Dimilin and XRD appeared to be the most toxic to the dipterous larvae and mites, respectively. While IKI gave the minimum toxicity to both survivors. On the other hand, with sheep dung an inverse trend was observed i. e., IKI and Dimilin were the most toxic to mites and dipterous larvae, respectively. Whilst, the least toxicity were obtained when CME and XRD were used on dipterous larvae and mites, respectively.  相似文献   

14.
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.  相似文献   

15.
The recent decline of Mediterranean oak woodlands in SW Iberian Peninsula is related to insect pests which affect both cork oak (Quercus suber) and holm oak (Quercus rotundifolia). We identified twenty-six bird species as potential regular predators of twenty major pests by reviewing the diet of breeding, wintering and resident species in this ecosystem. Foraging guilds are strongly associated with predation at distinct stages of the pests’ life-cycle: ground-foragers prey on overwintering pupae and larvae of seed-borers, tree-foragers prey on eggs, larvae and pupae of defoliating and wood-boring pests, and aerial-sweepers prey on airborne imagines. Bird predation can cover the complete life-cycle of pest species because different species may be complementary due to a dissimilar exploitation of foraging niches and periods. Small generalist tree-foraging passerines are important pest predators given their high densities and widespread distribution in Mediterranean oak woodlands, but management practices can have a significant negative effect in their populations.  相似文献   

16.
Population trend and time of activity of certain true spiders (Araneida), collected from clover foliage in Egypt A general survey of spider populations in a clover field at Assiut, Egypt, using the insect sweep net, revealed that their populations underwent violent oscillations throughout the growing season. However, number of spiders increased progressively and reached their peak late in May. The Salticidae, Tetragnathidae, and Thomisidae were the predominant families. They were amounted to 32, 23, 20 per cent of the total number of specimens collected during this study, respectively. The Clubionidae, Linyphiidae, and Lycosidae were collected in fewer numbers than the first three families. Data showed a possible occurrence of seasonal and temporal succession in the activity as well as relative population density of the studied spider families. Their maximum period of activity centered around Noon especially during January and February. However, this period was shifted to 8: AM and/or 8: PM during April and May.  相似文献   

17.
Fumigants and residual insecticides are commonly used to combat stored grain pests. In recent years, consumer awareness of the health hazard from residual toxicity and the growing problem of insect resistance to these conventional insecticides have led the researchers to look for alternative strategies for stored grains protection. For example, diatomaceous earth (DE) can be effective against stored grain insects. In this study, DE was used to design amorphous nano sized hydrophilic, hydrophobic, and lipophilic silica in 15–30 nm size range. Nanocides are expected to reduce the volume of application and kinetics of development of resistance in pests. We hypothesized that surface-functionalized silica nanoparticle (SNP) might be a viable alternative to conventional pesticides. Entomotoxicity of SNP was tested against rice weevil Sitophilus oryzae and its efficacy was compared with bulk-sized silica (individual particles larger than 1 μm). Amorphous SNP was found to be highly effective against this insect pest causing more than 90% mortality, indicating the effectiveness of SNP to control insect pests.  相似文献   

18.
A survey of stored product pests, their natural enemies, grain storage and pest management approaches in northern Namibia was conducted. The survey revealed five types of crop commodities (pearl millet, sorghum, cowpea, maize, feed mixture) stored in four types of grain stores (baskets, bag stags-flat stores, concrete bin, metal containers). No synthetic pesticides or plastic sheeting was recorded. Wooden-ash natural pesticide is the only protectant used. Ten insect pest species were found affiliated to the orders of Coleoptera (Attagenus fasciatus, Callosobruchus subinnotatus, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Rhyzopertha dominica and Tribolium castaneum), Lepidoptera (Corcyra cephalonica, Sitotroga cerealella), Psocoptera (Liposcelis paeta) and Blattodea (Blattella germanica). Out of these, seven species were recognized as new stored-products pests for Namibia. Although listed for southern Africa region, no storage pest-mites (Acari) and Sitophilus spp., Prostephanus sp. or Trogoderma sp. beetles were traced. We found four new species of natural enemies of storage pests recruiting from insects (Habrobracon hebetor, Cephalonomia wattersoni, Brachymeria sp.) and mites (Blattisocius tarsalis). The occurrence of natural enemies indicates a potential for pest bio-control in Namibian grain stores.  相似文献   

19.
The role of Azteca sp. ants as potential biological control agents was studied in an organic coffee farm in Chiapas, Mexico. Individual larvae of Pieris rapae were placed on trees with artificially enhanced ant activity and both time to disappearance of the larvae and ant activity were recorded. There was a general negative relationship between time to disappearance and ant activity. A census of spiders was made of coffee bushes with and without foraging Azteca, encountering a negative relationship between ants and spiders. These results indicate that Azteca ants have potential as pests through their positive effect on scale insects, but also have potential as biological control agents, through their negative effect on potential herbivores. Furthermore, the correlation between ant and spider densities suggests a complicated relationship between these two predatory organisms, implying a more complicated food web structure than simply ants, homoptera and other herbivores.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

20.
Dictyna sp. (Dictynidae) was the most common and abundant web-building spider on granati leaves. Rove beetles, lady beetles, ground beetles, ants and flower flies were recorded as beneficial insects ensnared in the webs. Rove beetles constituted 88% of the predatory complex. Among the destructive insect pests, aphids and whiteflies were entangled in the web-lines. Whiteflies represented the most common and abundant insectprey inside the webs. Furthermore, prey insects of order Homoptera occupied the 1st rank in abundance among other insect orders. Most of the prey were winged adults.  相似文献   

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