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1.
The mortality of adults, eggs, larvae and pupae of the cowpea storage bruchid,Callosobruchus maculatus (Fab.) was observed in four different high carbon dioxide (CO2) in air atmospheres (88% CO2, 70% CO2, 60% CO2 and 50% CO2) at 25°C and 32°C respectively, and 70% RH. All the developmental stages ofC. maculatus were completely killed within 5 days in the 88% CO2 in air atmosphere and within 12 days in the other high CO2 atmospheres tested. The adult and egg stages were most susceptible, and the old larvae and pupae, the least susceptible to the high CO2 atmospheres. Mortality ofC. maculatus was significantly influenced by the level of CO2, stage of insect development, exposure period and temperature.  相似文献   

2.
In stored-product fumigations mainly methyl bromide and phosphine are used. These toxic gases can contaminate the environment. A harmful effect on vegetable and animal organisms cannot fundamentally be excluded. The threshold concentrations of methyl bromide and phosphine in air were determined for water cress and lettuce. These species were chosen because of their high sensitivity representing other species of plants. Whereas lettuce was harmed already at about 400 mg CH3Br/m3, on water cress plants at 1400 mg CH3Br/m3 external harmful changes couldn't be found. The threshold concentration for lettuce treated with phosphine is between 3 and 8 mg PH3/m3. There is no difference between the development of water cress seeds in soil, which had been treated for 3 days with 4 mg–36g CH3Br/m3 or 20–1400 mg PH3/m3 and not treated soil. At high PH3-concentrations a higher growth of water cress plants occurred.  相似文献   

3.
Zusammenfassung Die Mortalität des KornkäfersSitophilus granarius nach Phosphorwasserstoffbegasungen ist stark von der Entwicklungsgeschwindigkeit der Gaskonzentration in der Anfangsphase der Begasung abhängig. Mit 0,08 g PH3/m3 — schlagartig und konstant appliziert — werden bei 20°C und 65% rel. Feuchte innerhalb von 48 h alle Tiere abgetötet. Bei langsam ansteigender und wieder abfallender Gaskonzentration, wie sie in Getreidelägern bei Begasungen auftritt, sind dazu 6 g PH3/m3 als Anfangsdosierung erforderlich, wenn die Versuchskammer mit 5% ihres Volumens pro Stunde mit frischer Luft gespült wird. Eine mittlere Konzentration von 1,55 g PH3/m3, die sich aus dem Integral der Konzentrationskurve mit 6 g PH3/m3 ergibt, führt in 10 Stunden zu 100% Mortalität.Etwa die 20fache Wirkstoffmenge bzw. die 5fache Zeit wird somit benötigt, um bei praxissimulierenden Begasungsbedingungen die gleiche Wirkung zu erzielen, wie bei konstanten Konzentrationen.Verschiedene Erklärungsmöglichkeiten werden diskutiert.
Response of the granary weevilSitophilus granarius (L.) to gradually increasing and decreasing phosphine concentrations
The response of the granary weevilSitophilus granarius to phosphine differs strongly depending on whether the insects are exposed to a gradually increasing concentration of the fumigant, as would be the case in a storage when PH3-releasing formulations are used, or to a constant concentration as is usually done in laboratory experiments.With an initial dose of 6 g PH3/m3 it takes 48 h at 20°C and 65% r.h. to kill all insects when the fumigation chamber is purged with fresh air at a rate of 5% of its volume per hour. A constant concentration of only 0.08 g PH3/m3 is necessary to give the same mortality in the same time.An average concentration of 1.55 g PH3/m3 — derived from the integrated concentration curve with an initial dose of 6 g PH3/m3 — kills all insects within 10 hours.Different mechanisms of response of the weevils to phosphine are discussed.

Mit 3 Abbildungen und 3 Tabellen  相似文献   

4.
Zusammenfassung Laborversuche über die Wirkung von Kombinationsbegasungen mit Methylbromid + Phosphorwasserstoff gegen Khaprakäfer-Larven und-Puppen bei 29, 25, 12 und 0°C sowie 75±5% rel. Feuchte zeigten, daß sich die letalen Einwirkungszeiten bei gleichzeitigem Einsatz dieser Gase beträchtlich verkürzen. Puppen reagierten empfindlicher als Larven, sowohl bei Begasungen mit CH3Br bzw. PH3 allein, als auch mit Kombinationen beider Gase.Ferner lassen die Untersuchungsergebnisse erkennen, daß sich CH3Br und PH3 in einer Kombinationsbegasung nicht gegenseitig beeinträchtigen, sondern zusammen wirken, wobei eine additive, in einigen Fällen sogar eine potenzierende Wirkung beobachtet wurde.Neben der besseren biologischen Wirkung dieser Methode ergibt sich als Vorteil der Kombinationsbegasung die Möglichkeit, die Methylbromid-Dosis zu reduzieren und damit die Rückstandsbelastung der Vorratsgüter auf ein Minimum zu beschränken, was besonders für Produkte mit einer hohen Sorptionsrate für Methylbromid, wie Expeller und Extraktionsschrote, vorteilhaft ist.
Tests on the efficiency of mixtures of methyl bromide and phoshine to Khapra Beetle (Trogoderma granarium Everts)
Investigations carried out in the laboratory at 29, 25, 12, and 0°C as well as 75±5% relative humidity about the toxicity of mixtures of methyl bromide and phoshine to larvae and pupae of Khapra Beetle showed that the lethal times (LT) required for killing the larvae and pupae with a combined fumigation of these two gases are considerably reduced. Also it was found that pupae are less susceptible than larvae to CH3Br and PH3 alone as well as to a mixture of these two gases.Furthermore, experimental results indicate that, in a combined fumigation of methyl bromide and phosphine, these two gases do not affect each other, but act independently, showing an additive, in some cases even a potentiated action. In addition to the improvement of the biological action of the gases by this method, a combined fumigation has the advantage of reducing the dosage of methyl bromide so that the residual effect can be restricted to a minimum on foodstuffs, especially for products with a high rate of sorption to methyl bromide such as expeller and extracted by-products of oil-seeds.

Mit 2 Abbildungen  相似文献   

5.
The larvae of the invasive maize pest Diabrotica virgifera virgifera (Coleoptera; Chrysomelidae, western corn rootworm) hatch in the soil in spring and search for maize roots following CO2 gradients. CO2 is one cue that might be used as an attractant towards soil insecticides, a mechanism already shown in laboratory experiments. This study compared the efficacy of several combinations of in or between-row applications of different rates of CO2-emitting capsules and/or soil insecticides (here tefluthrin) aimed at preventing root damage by the pest larvae under field conditions. CO2 emission of the capsules in the soil lasted up to 28 days with a peak after 21 days coinciding with the first larval hatch. The pest density in the soil was not high enough to cause root damage above the economic threshold. Furthermore all tefluthrin applications, regardless of whether at full, half or quarter rates effectively prevented root damage; thus CO2 did not significantly further increase this efficacy. In-row applications of tefluthrin with or without CO2-emitting capsules prevented root damage to a much larger extent (59–77 % on the node injury scale) than the between-row applications of tefluthrin with or without capsules (17–31 %). In conclusion, further research on belowground orientation and movement of D. v. virgifera larvae, as well as tests with combinations of CO2-emitting capsules and lower rates of soil insecticide are needed to potentially develop attract and kill strategies as a management option against this maize pest.  相似文献   

6.
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.  相似文献   

7.
The lethal and sublethal effects of chlorantraniliprole against Spodoptera exigua (Hübner) were evaluated under laboratory conditions by oral exposure of neonate larvae to the compound. The 72 h LC50 value of this insecticide to S. exigua was found to be 12.747 μg l−1. A progressive larval mortality of 24.32% for LC30 treatment and 42.61% for LC50 treatment was observed from 4th to 6th day after exposure, which resulted in the reduced pupation rates in exposure groups. The sublethal effects of this chemical were indicated by prolongation of larval period, the increase of pupal weight and decrease in hatch rate of egg. Chlorantraniliprole at LC30 and LC50 rate significantly delayed larval development; the developmental duration of surviving larvae was extended for 22.5 and 28.6%, respectively, compared with that of control group. LC30 treatment increased the mean weight of pupa and induced to the production of heavier pupa (>150 mg). In LC50 treatment, heavier pupa also showed up but the mean weight of pupa was not influenced. The egg hatch rate in LC50 group was significant lower than that in control and LC30 groups. No significant differences in pupal duration, emergence rate, sex ratio, egg number per female, and longevity of adults were observed among treatments. Chlorantraniliprole had exceptional activity against S. exigua according to concentration–response bioassay in laboratory, and the toxicities were primarily resulted from immediate lethality.  相似文献   

8.
Effect of temperature and relative humidity on embryonic development and egg hatch ofHyalomma marginatum Koch (Acari, Ixodidae) Effect of different temperatures (25, 30, 35, 40°C) and relative humidity (RH) levels (50, 75, 90%) on embryonic development and hatching ofHyalomma marginatum was investigated. The percentage of dead eggs and embryos, percentage of morphologically normal larvae, percentage of abnormally hatched larvae and percentage of larvae with morphological malformations were determined for each condition. Embryonic development and egg hatch proceeded at 25–35°C in all relative humidity levels tested. However 50% RH was unfavourable for these processes. The optimal conditions for larval development were found to be: temperature of 25–30°C and relative humidity of 75%. Under these conditions 72.7–87.8% of examined egg hatched into normal larvae.  相似文献   

9.
Bactimos was incubated for 30 days under 7 constant temperatures (i. e. ?20, ?10, 5, 25, 35, 40 and 45°C). The insecticidal activity of the compound was evaluated against 2nd and 4th instar larvae ofCulex pipiens molestus after 1, 3, 7, 10, 15 and 30 days of storage. No loss in the insecticidal activity of the Bactimos was detected after 30 days at ?20, ?10 and 5°C. At temperatures above 25°C the insecticidal activity reduced as the storage period increased. The LT50 value of Bactimos for the 2nd and 4th instar larvae at 24 h and 48 h exposure was found to decrease as the temperature increased.  相似文献   

10.
The Relative Growth Rate of the larvac ofA. rosae at a temperature of 20°C amounts to 0.45–0.63 (RGR of Myzus persicae=0.17–0.39) corresponding to a doubling of the body weight within 1.1 to 1.5 days. The daily intake of plant material reached twice the amount of the respective initial body weight. The diapause ofA. rosae is induced by the photoperiod; temperature seems to be of minor importance. The onset of pigment evasion from the larval eye signalizes the termination of diapause. Diapause ended earlier at temperatures of 5°C and 12°C than at 20°C but even at the latter temperature diapausing individuals eventually yielded adults.  相似文献   

11.
温度对杉木林土壤呼吸的影响(英文)   总被引：2，自引：0，他引：2  
Soil samples collected from the surface soil (0(10 cm) in an 88-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at the temperatures of 15°C, 25°C and 35°C in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35°C, followed by those at 25°C, and 15°C. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25°C, but it decreased to 1.2 at 25- 35°C. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period (on the 90th day) was less than 10% of the initial C amounts prior to incubation.  相似文献   

12.
The biological activity of essential oil extracted from coriander, Coriandrum sativum L. (Apiaceae) against eggs, larvae and adults of Tribolium castaneum (Herbst) was investigated in a series of laboratory experiments. Bioassays conducted in air-tight glass chambers showed vapour toxicity and strong repellency on filter paper arena test towards all the stages used. Responses varied significantly (P < 0.001) within insect stages, dosages and exposures. At 12.0 μg/ml dosage, mortality of adults reached 95%, but for 12-, 14- and 16-days larvae, mortalities were 65, 74 and 82%, respectively. On the developmental inhibition, individuals fumigated at the larval stage confirmed that the percentage of larvae reaching to pupal stage and pupae to adult stage, decreased significantly (P < 0.001) with increasing dosage concentration. The oil fumigation yielded 100% mortality for T. castaneum larvae, pupae and adults at 0.08 μg/ml dosage. The oil had fumigant activity against eggs and the toxicity progressively increased with increased exposure times and concentrations. One hundred per cent T. castaneum egg mortalities were obtained with oil fumigation at 20 μg/ml and 96 h exposure period. C. sativum oil also showed highly repellent activity to the adults of T. castaneum, with overall repellency was 90% and at a dosage of 12 μg/ml repellency was 100% in a filter-paper arena test.  相似文献   

13.
Larval development ofT. variabile under various environmental conditions is examined to estimate the potential damages in storehouses in Central Europe. Larvae develop between 21 and 37°C, lower temperatures considerably prolong the time of development: at 25° it lasts 48.3 days (♂ ♂) and 60.8 days (♀ ♀), at 30° 29.3 days (32.9 resp.), and at 35° 27.5 days (34.6 resp.). Female larvae on an average pupate after six larval instars, males after five. From this results the earlier pupation of the males. Isolated larvae do not pupate; they grow up to big and resistant dauerlarvae and possibly pass through a diapause of several years. Reared in groups larvae pupate promptly and diapause is terminated. Longevity, cold resistance and ability of starvation of dauerlarvae are examined. The results indicate that a development ofT. variabile in unheated rooms is possible. Because of the very slow development at lower temperatures economic important damages are unlikely.  相似文献   

14.
First instar honey bee larvae (0.2–0.4 mg) from outdoor (summer season) and flight-room colonies (winter season) were reared in an incubator on a semisynthetic diet. Parathion was either dissolved in the diet (0.01–10.0 μg/ml) or topically applied (0–0.5 μg) to the 3rd instar larvae. Increasing doses of parathion caused a delay in larval development and prepupal mortality. The half lethal concentration (LC50) of the insecticide, if applied in the diet, was 0.02 and 0.14 μg/larva, respectively, for summer and for winter larvae. The half lethal dose (LD50) after topical application was 0.18 μg parathion/larva. The utility of rearing honey bee larvaein vitro for evaluation of pesticide toxicity is also discussed.  相似文献   

15.
The incubation period ofM. incognita acrita eggs took 24–72 hours till the appearance of the second larval stage hatching from eggs in the laboratory at 25±5°C and at 60±5 R. H. The second larval stage, was observed in cotton roots 48 hours after the addition of it to soil beside cotton seedlings. The 3rd and 4th larval stage and adult female were observed in cotton roots 7, 11, and 24 days, respectively, after the addition of second larval stage to soil beside cotton seedlings. The total life cycle ofM. incognita acrita on cotton, (Gossypium barbadense) lasted for 33–38 days, at 25±5°C and at 60±5 R. H.  相似文献   

16.
Permanent culturing of Diprion pini L with regard to photoperiodic conditions Diprion pini can be permanently cultured in the laboratory under longday conditions (17/7 hours photo-scoto-phase). At 25 °C and about 80% rel. humidity one generation will be completed on the average within 40–50 days and at 20 °C within 50–55 days. Thus, 6–7 generations per year may be raised. The sensitive phase at which longday treatment prevents diapause is 30–10 days before cocoon spinning. The breeding technique used is described.   相似文献   

17.
Laboratory infectivity tests were undertaken to investigate the pathogenicity of “Bactimos” (a new commerical bacterial biocide) aginst different instar larvae ofCulex pipiens molestus. The biocide “Bactimos”,Bacillus thuringiensis var.israelensis, was confirmed as pathogenic for mosquito larvae ofC. pipiens molestus. At dosage of 0.000125 mg/250 ml water, mortalities of 25, 98, and 97% were recorded for the 1st, 2nd and 3rd instar larvae after 24 hrs, respectively. Dosage of 0.008 mg/250 ml water proved to kill all types of instar larvae (100% mortality) after 24 hours. Water volumes ranging from 100 to 800 ml, containing 0.005 mg “Bactimos” per each were found to kill the 2nd and 4th instar larvae (90–100% mortality) with no significant differences. In conclusion, it is quite evident that the commerical bacterialbiocide “Bactimos” should be recommended as biomortality agent against mosquito larvae in Upper Egypt.  相似文献   

18.
Essential oils of Achillea biebersteinii, Achillea santolina and Achillea mellifolium were obtained by hydrodistillation and analyzed using gas chromatography/mass spectrometry. The plant oils were tested for their toxic and repellent activities against the Khapra beetle, Trogoderma granarium (Everts) (Coleoptera: Dermestidae). T. granarium was sensitive to the oils via topical application, contact and fumigation bioassays, where A. biebersteinii oil was the most toxic regardless of the technique used. Using topical application, a dosage of 15 μg/mg insect of A. biebersteinii oil was sufficient to kill 100 and 83.2.0 % after 7 days exposure of adults and 2nd instar larvae, respectively. Meanwhile, twice this concentration of A. santolina and A. mellifolium oils caused 90.4 (72.5 %) and 73.8 (60.1 %) adult and larval mortality after 7 days, respectively. Using fumigation and 7 days exposure, a concentration of 50.0 μl/l air of A. biebersteinii oil displayed the strongest activity (percentage adult and larval mortalities of 100.0 and 88.0 %), respectively, while A. santolina and A. mellifolium oils at the same concentration caused 92.5 (76.8 %) and 76.1 (61.3 %) adult and larval mortality, respectively. The three oils were strongly repellent to the larvae and adults of T. granarium. The repellent activity was time and concentration-dependent, where A. biebersteinii oil was the most effective, even though at low concentrations (percentage repellency of 100 and 81.0 % were recorded against adults and larvae after 6 h exposure to a concentration of 0.22 μl/cm2, respectively). Results suggested the potential use of Achillea oils as natural grain protectants against T. granarium.  相似文献   

19.
During an outbreak ofN. sertifer in Brentonico (on Monte Baldo, Trentino, North Italy), in altitudes of 1,400–1,600 m, surveys were made in 1996 and 1997 on the voltinism of these short-day-Diprionide, wherely over 2,000 cocoons were reared (fig. 1; tab. 1–4). Therefore L4–5 larvae ofN. sertifer from different altitudes were transferred to Denno (430 m) and to Brixen (550 m) and were reared there under outdoor conditions. These surveys were completed with further observations of populations from South Tyrol, of St. Ulrich Val Gardena (1,200 m) and italian provenances from Riolo Terme (150 m) in Brixen (fig. 2). These comparative studies revealed a correlative connection between the time of cocoonspinning and adult emergence. They showed the following principle: the later the cocoonspinning, the earlier the adult emergence. Early spinners (e. g., May/June) emerge only late in October, while late spinners (e. g., early August) emerge as soon at the end of August. In the case of late cocoon spinning the obligatory summer cocoon diapause is so reducted, eventually—at the start of the short-day phase (with only 15 hours brightness), in early August—leading to a subitan development. These different cocoon spinning periods cause varying flywaves, W1–W4, ofN. sertifer, similarly to other Diprionidae; this seems evident also by pheromon-trap catches (fig. 2: 3). The possible variable combinations of these fly-waves are discussed. It is shown that voltinism and diapause behaviour ofN. sertifer are essentially conditioned by the photoperiod and correlated climatic factors. The determined low diapause rate, of just 1–2%, is connected with the southern and warmer location of the outbreak area of Brentonico (45° 45’ N). The exceptional longevity of adults, which can amount to several weeks, also plays an important role.  相似文献   

20.
Bactrocera minax is a major citrus pest in China, Bhutan, and India. It is univoltine and exhibits pupal diapause during winter. To better understand pupal diapause in this pest, we investigated pupal survival and pupal developmental duration under field and laboratory conditions. Specifically, we tested if pupal chilling was required for diapause development and termination. Nearly all mature larvae collected at the end of the citrus season entered pupal diapause. For pupae exposed in the field, natural chilling for less than 3 months resulted in more than 70 % mortality. However, exposure to winter conditions for 3 months or more both decreased pupal mortality and developmental duration when pupae were returned to the laboratory and held under constant temperature (25 °C). When pupae were gathered from the field in November and exposed to different chilling regimes in the laboratory, the chilling duration (30 vs 60 days) had significantly more impact on pupal survival than the specific chilling temperature (6, 8, 10, or 12 °C constant). However, both chilling duration and chilling temperature impacted on the pupal developmental duration, with longer chilling duration and higher temperatures decreasing pupal developmental duration. In conclusion, we demonstrated that pupal diapause development and termination in B. minax is strongly influenced by chilling conditions. Increasing cold exposure led to significantly and consistently faster adult eclosion and improved synchronization of adult emergence. This knowledge will help with the laboratory rearing of B. minax, an essential step in the long-term management of this pest.  相似文献   

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