摘要:

Hypothetical natural host population models were employed to calculate the impact of releasing parasites ofLixophaga diatraeae(Townsend) to controlDiatraea saccharalis(F.). The population models indicate that release of 1000 parasites per acre in Host Generation 2 would cause a subsequent accumulative suppression of the order of 97% by the 4th or last host generation. The principles governing effectiveness of strategic releases of parasites in relation to the host density as a method of suppressing sugarcane borer populations are discussed. The feasibility of suppressing and possibly cradicating the sugarcane borer by developing an integrated parasite-sterile insect release program is considered.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.1

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Seasonal changes of populations of the European corn borer,Ostrinia nubilalis(Hübner) were observed in one early-planted corn field in Waseca, Minnesota, from 1948 to 1970. The results of the 1st 10 years, 1948 to 1957, were published in 1959. This paper presents the results from 1958 to 1970, and discusses the population changes for the entire 23-year period.During this period some agricultural practices, natural enemies, and the varied climatic factors have been responsible for the haphazard variations of corn borer populations from year to year.Superimposed on these changes, there was a long term cooling trend from 1960 to 1969. The temperature in 1970 showed an upturn that was responsible for the highest corn borer population since 1949–52 peaks. It is concluded that corn borer populations in the area were kept at relatively low levels by environmental factors, but can return to an economically significant level when temperature becomes favorable.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.7

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Reproductive diapause was induced in adults of the grass thrips,Anaphothrips obscurusMüller, by exposing larvae to short days. Diapause was maintained by holding the adults in the short-day regimen for ca. 60 days at 21°C but thereafter adults terminated diapause and initiated reproduction. Short days and 15°C retarded but did not prevent termination of diapause. Diapausing adults collected from the grass fields in March and exposed to long days in the laboratory produced substantially more macropterous progeny than similar adults exposed to short days. The proportion of macropterous to brachypterous adults increased as a result of crowded conditions on their host plant (‘Exeter’ bentgrass) during development, but temperature or the quality of food did not appreciably affect the ratio of macropterous to brachypterous morphs. Temperatures that exceeded 25°C drastically increased the rate of reproduction and undoubtedly controls population density when other requisites are optimum. No males ofA. obscurusdeveloped in these experiments.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.16

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The toxicity of ½ and full recommended orchard dosages of 8 pesticides toHippodamia convergensGuérin-Méneville was assessed in the laboratory and the field. Endosulfan and binapacryl and the low dosage of oxythioquinox allowed 50% or greater survival of nondiapausing adults when sprayed directly upon the beetles in the laboratory. The higher dosage of oxythioquinox and both dosages of DDT allowed only 21–29% survival at 72 hours. Diazinon, carbaryl, parathion, and azinphosmethyl were highly toxic, allowing no survival after 6 hr. Essentially 100% mortality of nondiapausing adults resulted after 48-hr exposure in the laboratory to the residues of all 8 pesticides. In orchard tests, the low dosages of endosulfan, binapacryl, oxythioquinox, and DDT allowed 64% or greater survival of adults after 7 days' exposure to residues on peach foliage. Both the high and low dosages of diazinon and carbaryl were highly toxic through 7 days'. exposure but some beetles survived after exposure to 8- to 14-day-old residues. Residues of azinphosmethyl and parathion were highly toxic with no adults surviving after 7 or 14 days.Log dosage-probit curves for topical application of these pesticides with diapausing adults show a wide range of response, With LD50values from 0.005μg per beetle With azinphosmethyl to 5.5μg per beetle with binapacryl. The order of toxicity was azinphosmethyl>parathion>carbaryl>diazinon>DDT>endosulfan>binapacryl.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.20

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The total production of progeny by a single female of a tachinid,Eucelatoriasp., when species ofHeliothiswere used as hosts ranged from 144 at 20°C to 198 at 30°C and declined at temperatures above 30°C. The mean number per female rose from 68.2 at 20°C to 112.9 at 30°C and then dropped to 52.4 at 32.2°C and to 2.0 at 35°C. Mean female longevity declined from 61.8 days at 20°C to 17.9 days at 35°C. Males were 7–10 days shorter lived over the same temperature range.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.23

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

During 1968 and 1969, adultAlphitobius diaperinus(Panzer) were collected from turkey-brooder houses in Minnesota, Wisconsin, and South Dakota and were analyzed for bacteria and fungi. The lesser mealworms were surface disinfected, macerated, and cultured on different media; the choice depended upon experimental objectives.A wide range in the number of microorganisms was found within individual insects. Some harbored several thousand colonies, whereas others were comparatively clean.Micrococcusspp.,Streptococcusspp., and theBacillus subtilisCohn group were the most common gram-positive bacteria. Emphasis was given to gram-negative bacteria, especially those belonging to the Enterobacteriaceae group.Escherichia intermediaWerkman&Gillen was isolated from a relatively high percent of the insects.Salmonella saint paulKauffman-White occurred only in 3% of the insects, and this was from just 1 locality.Aspergillus flavusLink was the predominant fungus in the lesser mealworm, and an average of 25% was positive. Other species ofAspergillus, Penicillium,and the filamentous yeastlike fungiCandida,also were present but in relatively low numbers.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.27

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Attempts were made to identify bacteria normally associated withAnastrepha suspensa(Loew). Isolations (70), were made under aerobic conditions from apparently healthy field-collected larvae and larval trails in infested guavas, as well as from laboratory-reared eggs and larvae.Four different bacteria,Micrococcussp. (flavus-like),Erwiniasp.,Pseudomonassp., andP. ovalisChester were encountered. Although possible, none were isolated with such regularity as to suggest an intimate symbiotic relationship.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.30

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

An ecological study ofTetranychus urticaeKoch and its native predators was conducted on strawberry in southern California with populations being surveyed at weekly intervals during 1967–68. On Sept. 21 (4 weeks after planting), 98% of the plants were infested naturally with an average of 34.1 spider mites per leaflet. The population then gradually declined to 0.1 per leaflet by Nov. 21 with 4% of the leaflets infested remaining below 0.5 actives/leaflet through Jan. 23. The twospotted spider mite population started to increase in February and reached a peak of 139.3 actives/leaflet on May 21 with 100% of the leaflets infested. The population then declined abruptly to less than 0.5 mite/leaflet by June 18 and remained thus through the end of the study on June 25. The twospotted spider mite population crashed in each of the 8 study plots surveyed after reaching peaks ranging from 72.3 to 271.1 actives/leaflet with the peaks occurring from May 7–28. Seven insectan predators were present, with the dominantScolothrips sexmaculatus(Pergande) accounting for 84% of the total recorded. The predator population reached a peak of 3.64/leaflet on June 4. Fruit yield for the 4-month fruiting period (March–June) averaged 2.1 lb/plant (23.5 tons/acre). There was no consistent correlation between high spider mite populations and low fruit yield. It was concluded that the pest population crash was due primarily to physiological changes in the plants caused by high numbers of twospotted spider mites feeding thereon.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.34

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The study has shown that the Florida harvester ant,Pogonomyrmex badius(Latreille) (Hymenoptera: Formicidae) causes phosphorus and potassium to accumulate at the surface of colony sites in abandoned fields and along road shoulders. Soil samples from the crater surface of 5 harvester ant colonies contained 10.4±1.0 ppm phosphorus and 16.5±3.9 ppm potassium. Soil samples from control areas not associated with an ant colony contained 6.2±0.5 ppm phosphorus and 6.6±1.0 ppm potassium. The growth (height) of buttonweed,Diodia teresWalt, seedlings was greater in soils from ant mounds than in soils from control areas. The accumulation of nutrients is caused by the deposition of debris and waste products (seed covers, dead ants, feces, and other metabolic wastes) around the crater rim. The soil enrichment increases the standing crop of plants immediately surrounding the colony crater. The gradual mineralization of nitrogen and other inorganic nutrients is responsible for the continued greater growth of plants at sites abandoned for several years.Colonies are long-lived and may move to new locations several times during a period of years. The increased plant growth could possibly reduce the foraging radius of the workers by increasing local seed production.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.39

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Larval population trends of the alfalfa weevil,Hypera postica(Gyllenhal), and the distribution ofTetrastichus incertus(Ratzeburg),Bathyplectes curculionis(Thomson), andB. anurus(Thomson) were investigated during 1969 and 1970 in the central and southern regions of Pennsylvania.Weevil larvae began to hatch in mid- to late April in the southern regions and about 2 weeks later in the central regions. The population increased steadily and reached a maximum in 3–4 weeks after the eggs hatched. The larval population declined sharply following the peak. A partial 2nd peak occurred in midsummer in several of the regions, but no more than 10 larvae per sweep were collected at any sample site throughout the remainder of the growing season.Peak weevil larval populations were somewhat lower in 1970 than in 1969 in 3 of the 5 sampling regions. The population densities were highest in the west and the lowest in the east. A significant correlation was observed throughout the State between the longitudinal minutes of the sample sites and number of weevils found during the population peak in 1969. Significant correlations existed for these parameters in the southern region in 1969 and 1970 when these sample sites were analyzed alone.T. incertusandB. curculioniswere found in all the fields surveyed throughout the State.B. anurus,although released in the southeastern and south-central regions, was recovered only from the southeastern region.B. anurusappeared well synchronized with its host population.T. incertuswas found in alfalfa fields in early May, but parasitization was exceedingly low while the larval populations were high, never being greater than 4.5% in any region prior to mid-June. Percent parasitism increased substantially following the peak larval populations, and although it remained relatively high it fluctuated for a major portion of the growing season.Dispersal ofB. curculionisand its subsequent establishment throughout the State appeared to have occurred in a westerly direction and from release sites within the State. Percent parasitism at weevil larval population peaks was highest at or near release sites. Sample sites farthest from release sites, i.e. western regions, had the lowest percent parasitism. Effective parasitism byB. curculionisappears contingent on its ability to superparasitize the host and thus avoid encapsulation. In sample sites at or near release sites a more favorable density relationship appears to exist for superparasitization. The highest percent parasitism at the host population peak was observed at these sample sites.

ISSN:1754-5692    

DOI:10.1093/ee/1.1.42

出版商:Oxford University Press    

年代:1972

数据来源: OUP