摘要:

Interspecific competition between two orb-weaving spiders,Metepeira grinnelli(Coolidge) andCyclosa turbinata(Walckenaer), was investigated by selective removal of the predators. The estimated predation rate of small prey was higher whereCyclosawas alone than where both species were present, because whenMetepeirawas removed the density ofCyclosabecame higher than the combined density ofMetepeiraandCyclosawhere both species were present and because the consumption rate of small prey byMetepeirawas very low compared with that ofCyclosa.The study suggests that, in some circumstances, a subset of predator species could be more effective in reducing prey populations than the entire natural guild.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.177

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

The developmental responses of the fall armyworm,Spodoptera frugiperda(J. E. Smith), initially reared on each of four selected grasses for 4, 6, or 8 days and transferred to each of the other grasses were studied in the laboratory. Corn,Zea maysL., was the most suitable host, favoring a rapid weight gain, short development period, and low mortality for larvae and pupae. Development of fall armyworm previously fed on preferred host grasses, ‘Tifton 10’ and ‘Coastal’ Bermuda grass,Cynodon dactylon(L.) Pers., was primarily dependent on the suitability of the host grass to which the larvae were transferred. The most hardy fall armyworm larvae were those selected by 8-day feeding on resistant ‘common’ centipede grass,Eremochola ophiuroides(Munro) Hack., in that these hardy individuals developed more rapidly once they were transferred to susceptible grasses. Overall, resistance of centipede grass to fall armyworm was demonstrated whether neonate larvae fed initially on centipede grass or were transferred to the host as older larvae.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.182

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A dual-isotope porometer measured gas-exchange rates on almond leaves exposed to feeding damage byPanonychus citri, P. ulmi, Tetranychus pacificus, orT. urticae. The feeding injury of all four mite species caused significantly lower rates of stomatal conductance, mesophyll conductance, and photosynthesis compared with undamaged controls. No significant differences in gas-exchange rates occurred between species within either genus; however, significant differences between genera were detected.Tetranychusspp. caused lower rates of mesophyll conductance and photosynthesis when compared withPanonychusspp.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.190

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Light-trap studies were conducted to determine the dominant scarab species collected from turf areas in West Texas, the time and height of adult flight, and the effect of trap orientation.Phyllophaga crinitaBurmeister andCyclocephala pasadenae(Casey) were the most abundant scarab species collected, comprising ca. 89 and 11% of the total beetles caught, respectively. The peak flight ofP. crinitaoccurs 30 min earlier thanC. pasadenae.Trap orientation had no significant effect on the number of beetles collected of either species. The proportion of males exceeded 75% in both species. Vertical stratification was found in both species, but was most pronounced inP. crinita.Collections of both species were greatest at heights close to soil level.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.194

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

There was an effect of harborage-to-resource distance but no main effect of density on the frequency of feeding and drinking activity of adultBlattella germanica, videotaped continuously for 96 h. Feeding and drinking diel periodicity was more pronounced when the resource was placed further from the harborage with activity peaking ca. 2 h into scotophase and declining at the onset of photophase. Nongravid females and males fed and drank more often than gravid females, with a high percentage of females carrying oothecae never feeding or drinking during the recording period.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.198

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Field-collectedMelanoplus sanguinipes(F.) were reared in laboratory containers as isolated male/female couples, and the parasitization status of each individual was determined. Although number of eggs per pod and viability of eggs were similar for all females, parasitized females produced fewer egg pods than nonparasitized females.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.205

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Spores ofVairimorphasp. isolated from the cotton leafworm,Alabama argillacea(Hübner), and produced in the corn earworm,Heliothis zea(Boddie), were tested for their effect on caged adult honey bees,Apis melliferaL. The bees in each cage were fed 5.0 ml of spores suspended in 50% sucrose (wt/wt) at concentrations of 2.4 × 108or 6.0 × 108spores per ml. Survival of the bees over 23 days was recorded. Gut contents, thoracic muscles, and abdominal fat bodies of living and dead bees were examined for presence of protozoans. No significant difference between LT50's of treated and control bees was observed. There was no evidence ofVairimorphasp. infection of honey bee tissues. Examination of gut contents revealed protozoan spores in both control and treated bees. Spores within digestive tracts of control bees were probably those ofNosema apisZander, a common honey bee pathogen. Gut contents of treated bees contained spores that were eitherN. apisor part of the originalVairimorphasp. inoculum or both.Vairimorphasp. spores are not infective to adult honey bees under the conditions of this study and should be studied further as a possible biological control agent for certain crop pests.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.207

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Nonlinear models were used to estimate nondiapause larval and pupal development under constant temperatures using laboratory (North Carolina and Pennsylvania) and field (North Carolina) strains ofPlatynota idaeusalis(Walker) reared on semisynthetic medium and excised apple leaves. Significant differences in degree-day requirements due to sex were found in the pupal, but not the larval stage. Strain and food significantly affected thermal requirements for development and the effect occurred during the larval but not the pupal stage. Strain differences showed that North Carolina field strains and Pennsylvania laboratory strains developed faster during larval stage than the North Carolina laboratory strain. When larval and pupal thermal requirements were combined, total thermal requirements for strains were not significantly different. Insects developed faster on semisynthetic medium than on leaves for larval stage alone and larval and pupal stages combined. Lower threshold temperatures and thermal requirements for individual instars reared on medium were determined. Using the thermal requirements for larval and pupal development of the North Carolina field strain reared on apple leaves (478 degree-days over a threshold of 10.2°C:) plus the thermal requirement for egg development (116 degree-days over a threshold of 13°C:), the preimaginal thermal requirement for development is estimated to be 594 degree-days (1,069 Fahrenheit degree-days).

ISSN:1754-5692    

DOI:10.1093/ee/15.1.210

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Plant-mediated effects of growth-regulator herbicides (fluazifop-butyl, sethoxydim, and mefluidide) were observed in laboratory experiments using Mexican bean beetle (MBB),Epilachna varivestisMulsant, on soybean and lima bean plants. MBB larvae reared on sethoxydim-treated soybean plants took longer to pupate than did those on untreated plants, and pupal weights of MBB larvae reared on fluazifop-butyl-treated soybeans were reduced. Lima bean treated with fluazifop-butyl produced heavier MBB pupae than did untreated controls. MBB adults preferred untreated soybean plants in feeding tests over those treated with fluazifop-butyl or sethoxydim one day earlier, but 8–22 days later there was a preference for both hosts treated with these herbicides. Newly emerged MBB adult mating pairs caged on treated soybean plants produced greater numbers of eggs and egg masses per reproducing female than did beetles on untreated plants. These herbicides could have influenced the acceptability of the plants for feeding and their suitability for egg production and larval development by altering plant physiology.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.216

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A lethal yeast infection was characterized from laboratory colonies of the German cockroach,Blattella germanica(L.). External manifestations of infection included: shortened and curled antennal flagella, uneven wings. darkened and flaccid cadavers, Paralytic posture of cadavers, and a putrefied odor. The yeast cells (3 by 8 µm), examined with light and transmission electron microscopy, had thick cell walls and budding typical of the Eumycota. A definitive identification of the yeast was not made. Histopathological studies revealed emulsified fat bodies and high numbers of yeast cells (104–107CellS/µl)in the hemolymph of infected cockroaches. Infected cockroaches lost antennal flagellomeres; the number of flagellomeres present was directly related to the yeast cell density and the percentage of yeast cells that budded in the hemolymph. Yeast density increased and percent budding decreased as the infection progressed. The syndrome developed over 20 days and death occurred within ca. 30 days postinfection.

ISSN:1754-5692    

DOI:10.1093/ee/15.1.221

出版商:Oxford University Press    

年代:1986

数据来源: OUP