摘要:

Two strains of alfalfa, one with a high and one with a low concentration of saponin in the leaves, were tested for effect on the mortality of immatureMegachile pacifica(Panzer) exposed to leaf pieces in the nests. The average difference between strains was nonsignificant.Results did not support the view that saponin in alfalfa leaf pieces used in lining the egg cell are responsible for high mortality of leafcutting bees foraging on alfalfa.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.103

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Density of colonies together with size and spatial distribution of foraging territories of the subterranean termite,Heterotermes aureus(Snyder), were determined on a 1600-m2bait sampling grid in a shrub-invaded desert grassland on the Santa Rita Experimental Range S of Tucson, Arizona. Bait units (toilet paper rolls) attacked on the first wk of the 52-wk study and those with large, mean weekly forager counts were considered as colony foci. Lateral spread of colony boundaries was followed weekly. After one yearH. aureushad attacked 22.8% of the bait units. Colony density was estimated at 190A/ha, mean territory contained 12.5 m2and mean number of individuals/colony was speculated to be 22,632.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.105

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

The purple scale,Lepidosaphes beckii(Newman), has been reduced from the 4th most important pest of Texas citrus to an incidental pest by the introduced parasite,Aphytis lepidosaphesCompere. The evidence of complete biological control is the scarcity of the purple scale during 1971–73 and the ability of the parasite to suppress the relatively small numbers of scales that increase following applications of carbaryl, sulfur, and azinphosmethyl.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.110

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

‘Canby’ red raspberry is immune and ‘Latham’ is susceptible to infestation byAmphorophora agathonicaHottes. During a 4-day period, nymphs gained more dry weight and nitrogen on Latham than on Canby. On Latham the dry weight and nitrogen content of honeydew were greater and lO× more total solids and 2× more total nitrogen were ingested than on Canby. Using the volume of honeydew produced per aphid as an index of the quantity of sap ingested, equal or greater volumes of sap were ingested on Canby than Latham. The ingestate from Canby was more dilute than that from Latham.The phloem tissue in petioles of intact Canby leaves was destroyed, but the xylem left intact, by stem girdling. Nymphs on girdled Canby leaves gained as much dry weight as those on normal Latham leaves. Those on the girdled leaves ingested more total solids and more total nitrogen than those on the normal Canby leaves. When girdled Canby leaves were shaded from light, and photosynthesis prevented, nymphs ingested more total nitrogen than those on normal Canby leaves. The levels of total solids ingested from the girdled and shaded and the normal leaves did not differ. On the girdled and shaded Canby leaves the gain in dry weight by the nymphs was intermediate between that on girdled leaves of Canby and normal leaves of Latham, and that on normal leaves of Canby.These results suggest that the immunity of Canby is related to the levels of both solids (largely sugars) and nitrogenous compounds in the ingestate ofA. agathonica. It is not known whether this relationship is quantitative and/or qualitative in nature.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.115

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Movement ofPissodes strobi(Peck) adults in spring was studied by a method of individual marking, release, and recapture. More than ½ of the weevils released changed trees only once (57%), and none changed trees more than 4 times. Longest flights recorded in the study were 46.4 m for males and 53.0 m for females. Movement direction was significantly correlated with the direction of tree rows. A total of 75.9% of the marked weevils remained in or near the release area.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.120

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

A population model of cotton growth and development in response to weather, agronomic factors, and insect pests has been successfully used to examine cotton production in California. The impact of most arthropod pests on cotton yields is currently under investigation. Only the effects of defoliating insects,Spodoptera exigua(Hübner),Trichoplusia ni(Hübner), andHeliothis zea(Boddie), are reported here.The impact of moderate defoliation byS. exiguaandT. nipopulations causes only slight yield reductions. More important is the predation byS. exigualarvae on immature fruit (i.e., squares). Investigations on the interaction of plant age and developmental stage with defoliator damage (defoliation and predation on squares) indicates that the greatest yield reductions occur from attack early in the squaring period. The late season effects ofH. zeaare easy to measure and incorporate into the model.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.125

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Visual observations of predation byPardosa ramulosa(McCook) in alfalfa fields indicate that Hemiptera, Diptera, and Araneae are important prey of this wolf spider. Time-sort pitfall trapping showed thatP. ramulosaand some of its more frequently taken prey species are primarily active during the day. Population samples of the predator and prey species were taken to ascertain seasonal relationships.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.137

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

The proportion of males to females ofNeomesomermis flumenalis(Welch), andIsomermis wisconsinensisWelch, increases with increase in the number of nematodes per host. Collection of larvae ofProsimulium mixtum/fuscumSyme and Davies andSimulium venustumSay with 1, 2, 3, or 4N.flumenalisper host had 11.9%, 43.9%, 81.7%, and 93.8% male mermithids respectively. A similar increase in the proportion of males with an increase in parasite density was observed inI wisconsinensis. Most hosts were parasitized by a single mermithid.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.142

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Repeated treatments of the insect growth regulator (IGR), Altosid® EC4(isopropyl 11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate), at the rate of 0.1 ppm (0.27 lb/acre) to experimental ponds reduced abundance of several arthropod prey and predator species. Because of the size differential among affected species, the altered community biomass reflected the impact of Altosid more profoundly than abundance. Pupae of the mosquito,Culiseta inornata(Williston), were devastated by the IGR, representing large potential losses of biomass during the height of the mosquito breeding season. Chironomid larvae were reduced twofold by the treatment, and their importance to the biomass increased with rising spring water temperature. Preliminary laboratory and pond assays determined that Altosid induced mortality in early and late instars of the mayfly,Callibaetis pacificusSeeman. During colder winter months mayflies were eliminated from ponds under repeated treatment but populations in check ponds remained low and contribution to total biomass was slight. Rising water temperatures reduced IGR impact on the mayfly population. The ostracod,Cyprinotussp., was a major prey component and was not affected by treatment. A major predator, the larval dytiscid beetle,Laccophilussp., was eliminated from the treated ponds. This loss represented 84% of the predator biomass during one period. Odonata naiads comprised the 2nd major group of predators throughout the study. These naiads preyed heavily on mosquitoes and ostracods and were not affected by the IGR.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.145

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Micrometeorology of summer alfalfa in Phoenix, Ariz., and its relation to resident insect pests, particularly the beet armyworm,Spodoptera exigua(Hübner), is discussed. Solar and net radiation, air and soil temperatures, wind speed, relative humidity, evaporation, soil heat flux, and soil moisture data were collected at weekly intervals throughout a typical growing cycle. Measurements were made concurrently within a mature uncut canopy and a freshly cut field to emphasize the impact that periodic canopy removal has on insect populations. Evapotranspiration and shading by a dense interlocking canopy prevented midday temperatures from reaching 35°C (Tamb= 44°C) and kept vapor pressure deficits (VPD) less than 10 mm Hg. Simultaneous measurements in the cut field revealed surface temperatures of 63°C and VPD's at +1 cm of 77 mm Hg. Temperatures and VPD's in the cut field 1 wk after irrigation were more moderate in comparison.The windrow microenvironment provides a temporary refuge from climatic extremes present in the cut field until plant growth, stimulated by irrigation, produces conditions more favorable for insect development. Eggs and larvae are especially limited by the microclimatic extremes and reduced food supply during the pre irrigation period. Pupae collected from burrows beneath windrow vegetation exhibited significantly less mortality than those collected in the open. Adults utilize both windrow microhabitat and cracks within the soil surface to reduce evaporative water loss and prevent body temperatures from surpassing physiological tolerances.Cultural practices which maximize the effect of macroclimatic extremes such as timed cutting, rapid windrow removal, and a short delay in irrigation are indicated when insect populations attain economically important levels.

ISSN:0046-225X    

DOI:10.1093/ee/4.1.153

出版商:Oxford University Press    

年代:1975

数据来源: OUP