摘要:

Declining infestations ofDendroctonus frontaliswere studied in terms of within-tree, within-spot, and within-area survival between a severe and mild winter. While brood survival differed dramatically between the 2 winters, the net effect on population trends was the same. Infestations in the study areas neither survived nor proliferated during the following spring and summer. During the severe winter of 1976–77 nearly 100% brood mortality occurred following a period of subfreezing temperatures and this was directly responsible for spot collapse. During the mild winter of 1975–76 survival was dependent on brood stage and location within the tree. Brood survival, which was comparable to that from the previous late summer and autumn, was not the cause of spot mortality. Periodic emergence during intermittent warm periods and a tendency to disperse combined with high dispersal losses were thought to be responsible.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.231

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

An environmental chamber which maintains any desired temperature between 10°C and the avg daily ambient temperature (±1°C) is easily made in the field or laboratory by insulating a water bath and using a sunken container of ice as a heat sink. The test cages are partially submerged near the water surface.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.236

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Field populations of overwintered alfalfa weevil adults were studied in central New York from 1971–73 to measure the impact of the parasiteMicroctonus aethiopoideson ovipositIOn of selected alfalfa weevil populations. Seasonal peak parasitism of overwintered weevils ranged from 20–88% and oviposition by parasitized alfalfa weevil populations was reduced an avg of 47%. Host oviposition reduction was due to sterilization of female weevils and their subsequent premature death as compared to unparasitized weevils. The timing and magnitude of parasite oviposition relative to that of host oviposition was the key factor in determining the impact of this parasite on the oviposition potential of its host.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.238

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Predator-prey relationships betweenGeocoris punctipes(Say) andHeliothis virescens(F.) were studied in the laboratory by cagingG. punctipesnymphs individually withH. virescenseggs or larvae. The primary objectives of the study were to determine which stages ofH. virescenswere acceptable as prey for each nymphal instar ofG. punctipesand how this predation affected the developmental rate and percent survival of the predator's 5 instars.First-instarG. punctipesnymphs were discovered to be almost exclusively egg predators; the last 4 fed on both eggs and small larvae. All predator stages attained a survival rate of over 96% when they fed on eggs, but when feeding on 1st-instar larvae, survival ranged from 5.6–69.0% for all instars.Predator survival, feeding and development rates decreased as size (or age) of its prey increased; survival rate and feeding rates increased with each successive instar.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.245

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Winter survival of pupae of the fall armyworm,Spodoplera frugiperda(J. E. Smith), was studied in relation to temperature and rainfall at 4 locations in Peninsular Florida. Moth emergence was greatest (51.0%) at Homestead, intermediate (27.5%) at Bradenton, and lowest (11.6%) at Sanford and Gainesville. The number of days required for emergence ranged from 15–35 and generally was greater for northern locations. Emergence of adults was positively correlated with mean soil temperature, and respective centigrade soil and air degree day values for emergence were 170 and 143.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.249

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Adult rangeland grasshoppers,Aulocara elliotti(Thomas), from 2 geographically isolated wild populations were maintained at warm (24° night and 30°C day) or cool (18° night and 24°C day) temperatures and fed Western wheatgrass (Agropyron smithiiRydb.) grown in a greenhouse insectary at the same warm or cool temperatures or collected from the field where diurnal temperatures fluctuated widely during the rearing season (0°–34°C). Not only were fecundity, egg viability, and female longevity significantly affected by insect rearing temperatures, but the growth temperatures of the host plant also caused significant variation in these characteristics. Grass grown at cool temperatures increased the rate of egg production and decreased the avg female longevity. Females fed field grass had the lowest rates of egg production and lived the longest, while those fed grass grown at warm temperatures had intermediate rates of egg production and avg longevities. The effect of the host plant on reproduction was modified, however, by the temperature at which the insect was reared and by other factors within the populations. These results may provide a basis for evaluating the fluctuations in natural populations of grasshoppers.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.253

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

AdultPhilonthus flavolimbatusErichson collected near College Station, TX, in 2-day-old bovine manure pats were used to establish a laboratory colony. In subsequent laboratory tests, 5 adult beetles placed on manure reduced the number of adult horn flies,Haematobia irritans(L.), that emerged from 100 eggs to 6 (a 91% reduction when corrected for control mortality) and 10 beetles almost completely (+99%) eliminated production of adults from 100 eggs. The reduction was primarily the result of predation on the eggs. In simulated field tests, similar ratio of one beetle to 10 horn fly eggs gave only a 72% reduction.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.259

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Feeding behavior ofElasmopalpus lignosellus(Zeller) larvae was altered in simulations of no-tillage and mulched conventional tillage when compared to simulated conventional tillage. Larvae released in32P-labeled dead wheat or rye stalks assimilated significant amounts of radioactivity. Gut contents of larvae retained on dead wheat stalks indicated that dead organic matter was ingested.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.261

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Males of the western pine shoot borer,Eucosma sonomanaKearfott, were attracted to a mixture ofE-9 and Z-9-dodecenyl acetates. Maximum attraction occurred with between 5 and 50%E-isomer. Extracts of female abdomen tips appeared to contain these materials atE:Z ratios of between 1:3 and 1:2. The presence of Z-11-tetradecenyl acetate inhibited the response ofE. sonomanato these attractants. While screening materials forE. sonomana, the related (Eucosmini) speciesRhyacionia zozana(Kearfott) also was trapped.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.265

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Diapause production of the tobacco hornworm,Manduca sexta(L.), on flue-cured tobacco in North Carolina is examined and quantified. The resultant simulation model uses an ovipositional preference matrix constructed from egg counts on various phenological states in experimental field plots in different areas. The model considers foliage consumption of the pest species and the effect of parasitization on host feeding. It requires host plant data inputs, provides damage information, and predicts potentially overwintering populations as related to existing cultural practices and hypothetical situations meaningful in developing long-term management strategies.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.268

出版商:Oxford University Press    

年代:1979

数据来源: OUP