摘要:

Effects of relative humidity at 23°C on eggs of the bluegrass webworm from a New Mexico and a Kentucky population were compared. Over 90% of the fertilized eggs hatched above 60% RH in both populations. Although mortality varied inversely with RH between 10 and 50%, eggs from the New Mexico population exhibited comparatively greater hatching success and therefore appear to be more resistant to desiccation. Completely dry air was lethal to all eggs of both populations.Development of bluegrass webworm eggs from New Mexico accelerated as relative humidity increased. At 30% RH, the required time for half of the eggs to hatch was 228–240 hr; at 100% RH the required time was 180–192 hr.No significant differences between the 2 populations were found in terms of how maternal decapitation affected hatching and fertility of eggs.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.218

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The humidity response of adult sawtoothed grain beetles,Oryzaephilus surinamensis(L.), was investigated by using alternative chambers in which the beetles were presented with a choice between 2 relative humidities. The direction (hygronegative or hygropositive) and intensity of the response depended upon sex and upon the position of the alternatives on the relative humidity (RH) scale, but, in general, the beetles showed a pronounced avoidance of high humidities and a lesser avoidance of low humidities. The intensity of the hygronegative response to 100% RH and various alternative humidities was independent of the difference between alternatives, at least when the difference was 9.3% RH or more. Between the limits of 44.4 and 75.6% RH, the intensity of the hygronegative response of males to alternatives of 60 and 100% RH was only very slightly influenced by the humidity conditions to which they had previously been exposed. However, prolonged exposure to 0% RH resulted in a reduced response.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.221

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

When female screwworm flies,Cochliomyia hominivorax(Coquerel), were allowed continuous opportunity to oviposit on artificial medium, more than 32% of a population of wild-type (wound-reared F1–F5. progeny of native flies) females failed to oviposit, but only 3% of a population of laboratory-adapted females (progeny of strains reared on artificial medium>150 generations) laid less than 1 egg mass. Also, peak oviposition of the 1st egg mass occurred about 4 days earlier with the laboratoryadapted females than with the wild-type females, and there was a highly significant difference (P<0.01) between the 2 groups in the mean number of egg masses per female. Oviposition by virgin wild-type females occurred rarely (about 4%), but there were almost no virgin females among laboratory-adapted populations by the time the flies reached sexual maturity.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.227

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The biology of 3 known biotypes (A, B, and C) ofSchizaphis graminum(Rondani) was studied at various temperature gradients from 10.0° to 32.9°C In the laboratory. Host plants included greenbug-resistant and susceptible barleys and sorghums. The optimum temperature for reproduction as between 21.9 and 23.9°C. The minimum constant temperature at which reproduction occurred was 10.0°C; the maximum was 32.9°C. Resistance in sorghum increased as temperature increased. The fecundity of greenbugs was generally much lower on resistant than on susceptible plants. Biotype C was better adapted than A or B to either temperature extremes. At cycling temperatures the greenbugs were capable of recovering and reproducing at a much higher rate than at constant extreme temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.230

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

A series of laboratory experiments was conducted to study one of the possible explanations why the endoparasitic hyperparasite,Alloxysta victrix(Westwood), was numerically more abundant by a 2:1 ratio in previous field studies over the ectoparasitic hyperparasite,Asaphes californicusGirault.It was hypothesized that perhaps a time factor or the day of attack in reference to the developmental stage of theAlloxystalarva/pupa within the aphid mummy could influence the competitive success or failure of the femaleAsaphesin her attempt at hyperparasitization as a tertiary. The host aphid was the pea aphid,Acyrthosiphon pisum(Harris), and the primary parasite wasAphidius smithiSharma&Subba Rao. The developmental time of the 1st hyperparasite,Alloxysta,inside the aphid mummy was long enough to permit 11 test-days for attack by the 2nd hyperparasite,Asaphes.Results of these laboratory experiments on hyperparasite competition indicated that 89.3% of the hyperparasites which emerged from mummies containingAlloxystaand attacked byAsaphesduring the 1st half of the test-period (Days 1–6) wereAsaphes,and only 10.7% wereAlloxysta.However, during the 2nd half of the test-period (Days 7–11), successful hyperparasitization byAsaphesdecreased to 33.4%, and conversely 66.6% of theAlloxystasurvived this attack and emerged as adults.Thus, the ectoparasiticAsaphesdoes not invariably dominate the endoparasiticAlloxystawhen the 2 hyperparasites come into direct association, as had been supposed. The numerical abundance and apparent competitive superiority ofAlloxystaoverAsaphesin previous field studies is due not merely to its greater specificity and higher searching efficiency, but to its ability to compete successfully withAsaphesby increasingly surviving attack the later this occurs during its development inside the mummy.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.234

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

An investigation of effects of sewage effluents on populations of microarthropods living inSpartinamarshes was carried out in the spring and summer of 1970, using primarily a vacuum collecting technique. Comparisons of dominant forms, population densities, and species diversities were made between populations inhabiting marsh grass exposed to flooding by treated sewage wastes and those in nonpolluted areas. Only in the case of spiders and amphipods were significant differences found, with density in both cases being greater in the polluted marsh. Species diversity was relatively high, especially for populations fromSpartinagrowing within margins of artificial ponds, some of which were also exposed to treated sewage wastes.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.244

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Populations ofManduca sexta(L.) were reduced by 86% on St. Croix, U. S. Virgin Islands, when blacklight traps at a density of 3/mile2were operated for 43 months; during the last 22 months, most traps were baited with virgin female tobacco hornworm moths. The collections indicated that hornworms were present throughout the year and that 2 periods of high population occurred each year, both associated with rainy seasons. When the collections of females from 9 traps operated for a year before the mass trapping began were used as a base for comparison, the yearly reductions in the mean collections for 12 months ending in December were: 60% from 1966 to 1967; 51% from 1967 to 1968; and 24% from 1968 to 1969. Annual operation of blacklight traps during the periods of maximum activity of the tobacco hornworm moth would reduce populations of the insect in similar situations and probably also in continental land masses.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.253

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The efficiency of 3 predators,Geocoris bullatus(Say),Nabis americoferusCarayon, andCoccinella transversoguttataFaldermann, used singly and in combination, was evaluated against 3 prey species, the green peach aphid,Myzus persicae(Sulzer), the zebra caterpillar,Ceramica picta(Harris), and the bertha armyworm,Mamestra configurataWalker, on caged sugarbeet plants in the greenhouse. Coccinellids used alone or in combination with other predators were effective in reducing populations of green peach aphids. Also, nabids or geocorids alone were effective in reducing the population of aphids for about 1 week if the initial population averaged no more than 14 aphids per plant and if the predators were present at a rate of about 1 per plant; however, when the population of aphids was 34 per plant, nabids or geocorids alone were not effective. Nabids alone or in some combinations were superior to all other treatments in reducing the population of the noctuid species when these larvae were small.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.258

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

When incidence of parasitism and diseases of insects are to be determined by recovering the organisms, large numbers of field-collected insects often must be brought into the laboratory. Parasites can be recovered by rearing their hosts until the parasites emerge either as adults or as mature larvae. At the Northern Grain Insects Research Laboratory at Brookings, S. Dak., we developed a collecting technique for use in field studies to recover parasites and to determine incidence of parasitism in the armyworm,Pseudaletia unipuncta(Haworth); the army cutworm,Euxoa auxiliaris(Grote); and the pale western cutworm,Agrotis orthogoniaMorrison.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.264

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Present knowledge of mating behavior in fireflies is limited to species in which adults are luminescent: because of their mating glows or flashes these fireflies have attracted special attention (Lloyd 1971). But the adults of many species have no lights and nothing is known of their mating signals or behavior. In July of 1971 I made observations on 3 such species in 3 different genera.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.265

出版商:Oxford University Press    

年代:1972

数据来源: OUP