摘要:

During the summers of 1972–73, 10 fish species were evaluated as predators against larvae of the dark rice field mosquito,Psorophora confinnis(Lynch-Arribalzaga), near Stuttgart, Ark. Stocking rates were 0.02, 0.03, and 0.06 fish/ft2. At the lowest stocking rate green sunfish,Lepomis cyanellusRafinesque, reduced larval numbers by 89.7% and were significantly more effective than adult mosquitofish,Gambusia affinis(Baird and Girard). The white amur,Ctenopharynogodon idellaValenciennes, was intermediate in effectiveness when compared with the above. At 0.03 fish/ft2, green sunfish reduced larvae by 99.2% and were significantly more efficient than juvenile mosquitofish, which had little effect on the larval population. At the 0.06 fish/ft2rate mosquitofish; white amur; Israeli carp,Cyprinus carpioL.; and hybrids (Israeli carp × goldfish) were significantly more effective than bigmouth buffalo,Ictiobus cyprinellus(Valenciennes); black buffalo,Ictiobus niger(Rafinesque); goldfish,Carassius auratus(L.); or juvenile mosquitofish. Recovery counts of fish indicated that fish survived under natural conditions in Arkansas rice fields.

DOI:10.1093/ee/3.5.823

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Phytophagous insects representing 7 orders, 31 families, and 87 species are reported as comprising the insect fauna ofAmbrosia acanthicarpaHooker (Compositae) in southern California. Most insects found attacking this native ragweed were euryphagous, ectophagous, sap– and foliage-feeding species. About a third reproduced on this plant. Fourteen (19%) of the 73 identified associates were stenophagous species, their host plants apparently confined to the tribe Heliantheae. About a third of these identified associates were minor or major pests of cultivars.

DOI:10.1093/ee/3.5.827

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Phytophagous insects representing 6 orders, 27 families, and 55 species are reported as comprising the insect fauna ofAmbrosia chamissonis(Lessing) Greene (Compositae) in southern California. Most insects found attacking this native ragweed were euryphagous, ectophagous, sap- and foliage-feeding species. Nearly half reproduced on this plant. Nine (20%) of the 44 associates identified to species were stenophagous, their host plants apparently confined to the tribe Heliantheae. Ten (23%) of these were minor or major pests of cultivars.

DOI:10.1093/ee/3.5.835

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Sinella curvisetaBrook was cultured for 170 days under optimum conditions (30°C and 100% RH). Under these conditions the Collembola demonstrated a high biotic potential (γ = 0.36) and a high replacement rate (Ro= 515 per female). It was postulated that since there was such a high replacement rate that a large portion of the eggs laid must reach reproductive age. This was the case, with 74% of the eggs laid reaching the reproductive group.The study was not performed under natural environmental conditions; consequently, the application of the results to the real world may be questionable. However, it was concluded that, since this study was conducted under optimum conditions, fecundity, replacement, and biotic potential results could be interpreted as maximum values.

DOI:10.1093/ee/3.5.840

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Study of long-term impact of extremely low frequency, low intensity antenna radiations and electromagnetic fields at the Navy's project Sanguine Wisconsin Test Facility continued in summer, 1973, with population analyses of soil arthropods in 9 test and 6 control plots. In 1973, 13 out of 19 plots and subplots had fewer arthropods than in 1972. The even distribution—7 test and 6 control plots—rules out a Sanguine effect. The 3 main test subplots are spaced 30 yards apart and have similar flora, soil, and exposure; yet between 1972 and 1973, total population doubled in one subplot, halved in another, and remained the same in the third. Control subplots showed similar variability. Evidence for a stabilized micropredator-prey system is the absence of significant differences in proportions of predators (Mesostigmata, Prostigmata) in 7 of 9 test and control pairs, monthly and for the entire summer. In 8 of 11 tests (73%) and 5 of 8 controls (63%) there was also no significant shift in proportions of predators between 1972 and 1973: the 6 significant shifts occurred equally among tests and controls. Predator densities in paired plots monitored for 3 years have not differed significantly. After 4 years of antenna operation, Cryptostigmata:Collembola ratios in test and control plots are roughly the same, and approximate the 1969 pre-treatment ratios. Other data support the hypothesis that 4 years of ELF operation has not Altered soil micro-arthropod population structure near the antenna.

DOI:10.1093/ee/3.5.845

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Seasonal abundance of insects and mites was measured with the aid of insect traps in 4 wooden farm granaries in Manitoba at weekly intervals during May–November for 3 years. Each granary contained 13.6 metric tons of wheat, which was dry and biologically unheated in 2 granaries, and partially damp and biologically heated in the other 2. More insects and mites were found in heated than in unheated granaries. Of the 18 kinds of arthropods trapped, 2 kinds of insects,Cryptolestes ferrugineus(Stephens) and Psocoptera, and 2 kinds of mites,Acarus siroL. andTarsonemus granariusLindquist, occurred monthly in 2 heated granaries. No single species of the insects and mites occurred in every month in unheated granaries;C. ferrugineus, Psocoptera andAndrolaelaps casalis(Berlese) occurred most often.Ahasverus advenaWaltl occurred only in heated granaries during May–November.Lathridius minutus(L.) occurred in unheated granaries during May–July and in heated granaries during May–October.Cryptophagus varusWoodroffe and Coombs occurred in unheated granaries during September–October and in heated granaries during July–October. The continued activity of adults ofC. ferrugineusfrom May–November in both unheated and heated granaries in most years shows unusual adaptation of this important storage pest of cereals which enables it to withstand and adjust to the harsh climate of the Canadian Prairies. Temperature was found to be the most important factor affecting seasonal changes in the populations of most species of insects and mites studied.

DOI:10.1093/ee/3.5.854

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Pupae of the tobacco budworm,Heliothis virescens(F.), diapausing and developing larvae of the codling moth,Laspeyresia pomonella(L.), diapausing larvae of the pink bollworm,Pectinophora gossypiella(Saunders), and diapausing pupae of an oak silk-worm,Antheraea pernyiGuérin-Ménéville, were exposed in cubicles to 1-h light breaks interjected into the scotophase following the photophase during fall, winter, spring, and early summer. The emergence of adult oak silkworms in the spring and early summer was accelerated compared with the controls by a 1-h light break interjected any time during the night. Termination of diapause in pink bollworm and codling moth larvae was delayed by a 1-h light break interjected into the dark period 20 h after dawn. Diapausing tobacco budworm pupae did not survive the winter but development to pharate adults occurred when 1-h light breaks were interjected 15, 16, 20, or 22 h after dawn.

DOI:10.1093/ee/3.5.863

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

The spatial pattern ofHypera postica(Gyllenhal) in Kentucky alfalfa fields was investigated using Taylor's and Iwao's distribution functions as statistical models. Field counts of the insect in 2 contiguous plots where the populations were relatively low conformed to an overdispersed pattern. However, at a 3rd plot where the density was high, numerous population aggregates were formed and they dispersed in the direction of randomness. Randomness also increased with development of the larvae, partially owing to mortality caused by the 2 parasiticBathyplectesspp. For all stages the variance was proportional to a fractional power of the mean. Taylor's power functionbvaried with environment. Use of one-quarter square foot samples for estimating egg populations had little effect on the skewness of the distribution.Two transformations are offered for stabilizing the variance of overdispersed field counts. However, only the square root transformation stabilized the variance of counts in the plot where the populations were randomly dispersed.

DOI:10.1093/ee/3.5.866

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Sampling variations inHypera postica(Gyllenhal) populations in Kentucky alfalfa fields were investigated using standard ANOVA procedures for nested random models. Inter-quadrat variance was the major source of population variation in 2 contiguous plots in which the spatial distribution conformed to an overdispersed pattern. Inter-block and inter-plot differences were rarely significant. There was no single major source of population variance at a 3rd plot where the field counts approached the Poisson series. The variance components associated with blocks, plots, and samples were significantly greater than zero in most cases. A least square fit of the form Log Y = Log a + bX31revealed a high correlation between sample size (Log Y) and mean density (Log X) for eggs and larvae when the data points from the 3 plots were pooled. An exponential function of the form Y=aebx–1/3was derived from the regression equation to plot the predicted relationship between sample size and mean density in the original scale. The number of samples required was inversely proportional to population levels for the low-density plots. However, when populations increased and the distribution approached the Poisson series at high density the graph levelled off asymptotically; this relationship was graphed for 2 levels of sampling precision. Populations of prepupae, pupae, and adults of the insect may be estimated with a 10% standard error of the mean from ten 1-ft2quadrat areas of alfalfa plants.

DOI:10.1093/ee/3.5.872

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Past studies have shown that sex pheromone communication in the cabbage looper moth,Trichoplusia ni(Hübner) can be disrupted by permeating the air the with synthetic pheromone of this species, looplure (cis-7-dodecenyl acetate), (Berger 1966, Gaston et al. 1967, et al. 1967, 1972). Successful disruption of pheromone communication between lepidopteran males and females may not be a function of the spacing between release points of synthetic pheromone, but rather may be dependent upon the amount of the chemical released into the air per unit area of land under treatment (McLaughlin et al. 1972, Shorey et al. 1972, Shorey and 1974). Thus, two different approaches can be taken in developing a pheromone-disruption technique. The devices from which the pheromone is to be evaporated(evaporation-substrates) may be placed close together (within cm apart) in the treated area, with each evaporation-substrate releasing pheromone at a low rate. On the contrary, evaporation-substrates may be spaced far apart (m or possibly km), emitting pheromone at a relatively high rate. Each approach requires different evaporation-substrate designs and different methods for distributing them. The former approach most likely requires pheromone to be impregnated into a small evaporation-substrate which releases pheromone continuously and is dispersed by aerial or other mass dispensing means. Periodic distribution of the evaporators would probably be required throughout the duration of the season. On the other hand, widely separated evaporators would require dispensers which release large nightly quantities of pheromone from fixed points in the area under treatment. Evaporators in this case could conceivably be engineered to release pheromone during only the night and function with a minimum of maintenance throughout the season.

DOI:10.1093/ee/3.5.876

出版商:Oxford University Press    

年代:1974

数据来源: OUP