摘要:

Brachymeria intermedia(Nees) was reared on its most prevalent host,Lymantria disparL., and onHolomelina lamae(Freeman), not a natural host of B.intermedia. Host acceptance levels for L.disparwere much higher than for H.lamae. Rearing on H.lamaeor adult experience with pupae of this species did not elevate its acceptability. When B.intermediawere deprived of hosts from emergence, the acceptance levels for L.disparand H.lamaeincreased with age of the parasitoid, although more so for L.dispar. In single-choice tests, H.lamaepupae contaminated with kairomone of L.disparwere accepted at the same rate as L.disparpupae. Experience with the contaminated H.lamaepupae increased the acceptance levels for clean H.lamae. The degree of polyphagy of B.intermediais discussed.

DOI:10.1093/ee/21.4.760

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Twenty-eight sugarcane fields in Florida were sampled for ants using baits or pitfall traps. Using baits, the imported fire ant,Solenopsis invictaBuren, was clearly the dominant ant species being found in the highest percentage of all fields, the highest percentage of all bait cards, the greatest total number caught, and the highest relative abundance. Using pitfall traps,S. invictawas again the dominant ant species being found in the highest percentage of all fields, the highest percentage of all pitfall traps, the greatest total number caught, and the highest relative abundance.S. invictawas first found in Florida sugarcane in 1970. Our data show that since 1970S. invictahas become the dominant ant species in Florida sugarcane resulting in a large reduction in the relative abundance of other ant species.

DOI:10.1093/ee/21.4.767

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Thrips calcaratusUzel is an introduced pest of basswood trees in North America. Its basic biology and life history are unknown because it is not injurious in its native European range. In the present study, the general life history ofT. calcaratusin Wisconsin was determined using emergence trapping, foliar sampling, and soil extraction. This species is univoltine; overwintered adults emerge from the soil in early spring, feed on buds as they open, and oviposit into the major veins on the undersides of leaves. The larvae feed on leaves, descend to the soil, and pupate. Degree-day models were computed for the free-living stages ofT. calcaratusand its host plant phenology. There is close synchrony betweenT. calcaratusemergence and basswood bud swelling and opening. Populations of three thrips associates—the pear thrips,Taeniothrips inconsequens(Uzel);the native basswood thrips,Neohydalothrips tiliae(Hood); and the predacious black hunter thrips,Leptothrips mali(Fitch)—were also monitored. The pear thrips is an introduced polyphagous pest that has caused severe damage to eastern maples and western fruit orchards but has not been heretofore reported in midwestern states.

DOI:10.1093/ee/21.4.771

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

The beet armyworm,Spodoptera exigua(Hübner), was reared at eight constant temperatures ranging from 15 to 38°C on an artificial diet, smooth pigweed,Amaranthus hybridus, or cotton,Gossypium hirsutumL. Developmental rates, survival, pupal weights, and number of stadia varied among diets. Both linear and nonlinear models were developed for the developmental rate of beet armyworm eggs, each stadium, and the entire larval and pupal stages on each diet. A developmental threshold of 12.42 ± 1.58°C was estimated for eggs. Larval developmental rates declined at 38°C on all diets. Pupal developmental rates declined at 36°C on all diets. Developmental thresholds were similar for all developmental categories on all diets and averaged 13.6 ± 0.46°C. The number of stadia increased at both high and low temperatures on all diets. Larvae took longer to develop, attained a lower pupal weight, and required a greater number of stadia on cotton than on artificial diet or pigweed.

DOI:10.1093/ee/21.4.780

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Laboratory studies determined that a decrease in the quality of potato foliage,Solanum tuberosumL., resulted in indirect competition between Colorado potato beetle,Leptinotarsa decemlineata(Say), and potato leafhopper,Empoasca fabae(Harris). Fitness of potato beetles decreased when they fed on potato plants damaged by potato leafhoppers. Potato leafhoppers produced fewer eggs on plants that had been partially defoliated by potato beetles or coated with excrement. Both species distinguished between damaged and undamaged foliage.

DOI:10.1093/ee/21.4.787

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Stethoconus japonicusSchumacher altered its oviposition site on azalea,Rhododendronspp., plants as the summer progressed. During June, eggs were deposited mostly in the midrib on the new growth. As leaves aged, the oviposition site shifted to current year's stems and the leaf scars of year-old growth. The shift in oviposition site was coincidental with a decline in leaf moisture of ≍9% and an increase in leaf age. Eggs deposited in the leaf midrib changed shape Significantly and increased in weight by 60% from day 3 to day 10; the sigmoidal curve fit a change in weight. As eggs aged from 2 to 10 d, they showed a significant increase in breadth, no change in length, and a significant reduction in width. Eggs ofS.japonicusbegan to hatch in the field in late June when early instars of the second generation of its prey, the azalea lace bug,Stephanitis pyrioides(Scott), were present. The late hatch of this specialist predator resulted in synchrony with the second generation of its prey. Asynchrony and late hatch of overwintered eggs makesS.japonicusa suitable candidate for IPM programs because the predator may escape the effects of pesticides directed at the first generation of azalea lace bug nymphs.

DOI:10.1093/ee/21.4.793

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Behavioral responses of the phytoseiid predatorsPhytoseiulus persimilisAthias-Henriot,Typhlodromus (=Metaseiulus) occidentalisNesbitt, andAmblyseius andersoniChant (Acari: Phytoseiidae) to the presence or absence of stimuli associated with the twospotted spider mite,Tetranychus urticaeKoch (Acari: Tetranychidae) and conspecific predators were studied in the laboratory using choice tests. Over a distance of 18–36 mm, slightly more starved females ofP. persimilisselected rose leaf disks that had been infested withT. urticaethan uninfested ones, whereas starved females ofT. occidentalisandA. andersonishowed no preference. All three predator species eventually aggregated on the infested leaf disks, althoughT. occidentalisresponded more slowly thanP. persimilisandA. andersoni, andA. andersonihad shorter residence time in prey colonies than did the other two species. More predators of all three species chose the branch of a Y-form runway that had been previously exposed to twospotted spider mites than the unexposed branch. MoreP. persimilisandT. occidentalischose the branch of the runway that had been previously exposed to conspecific predators than the unexposed one, whereasA. andersonishowed no preference. This comparative study concludes that (1) there are interspecific variations in foraging responses of phytoseiids to prey- and predator-associated stimuli, (2) aggregation of predators in prey colonies is primarily the result of arrestment rather than attraction, and (3) the intrapatch movement of some phytoseiid species among spider mite colonies is not random.

DOI:10.1093/ee/21.4.799

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Gene flow and movement among Hawaiian populations of the diamondback moth,Plutella xylostella (L.), were examined using indirect and direct methods. Estimates of genetic differentiation of subpopulations (FST)based on electrophoretic variation at four polymorphic loci varied from 0.038 to 0.028. Using Wright's method, estimates of the number of migrants exchanged per generation per population (Nem) fromFSTestimates based on four loci ranged from 6 to 9. There was little variation between islands, and only slightly more variation between Hawaiian populations and two populations from the continental United States (Fregion-total= 0.011). The results are consistent with the recent arrival of the diamondback moth in Hawaii. There has probably been sufficient time since its introduction for local populations to have differentiated, but it is less likely that enough time has passed for larger regional population units to differentiate from each other. Results from field experiments in an area surrounding a cabbage plot also suggest that diamondback moth is highly mobile. Average moth density in the 900 m2surrounding the plot was 7.8% of the density of moths within the plot, suggesting substantial emigration out of the plot. The data indicate that local variation in insecticide resistance among Hawaiian diamondback moth populations is not an indication of restricted gene flow and is most probably a result of local variation in selection.

DOI:10.1093/ee/21.4.808

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Performance of Colorado potato beetle,Leptinotarsa decemlineata(Say), was compared on greenhouse-grown tomatoes,Lycopersicon esculentumMill., fertilized with nitrogen rates of 0, 25, 50, or 75 mg N kg−1soil. Higher nitrogen treatments resulted in higher nitrogen concentrations in the plants, greater plant yields, and greater nitrogen uptake. The insects that developed on plants receiving more nitrogen showed significantly higher percentage survival from first instar to adult and a smaller number of insects remaining as larvae at the termination of the experiment. Higher nitrogen treatments also resulted in significantly more rapid insect development and greater pupal mass.

DOI:10.1093/ee/21.4.817

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Effects of temperature, age, and photoperiod on pheromone titer in the pheromone gland of gypsy moth,Lymantria dispar(L.), were studied with the aid of gas chromatography. In laboratory-reared females, daily rhythmic changes in pheromone content were observed with peaks occurring toward the evening and increasing in quantity with female age. In wild females held in outdoor cages under very hot afternoon conditions, maximum pheromone titer was observed in the early morning and minimum titer in the afternoon. However, pheromone-oriented flight activity of the wild males was lowest in the morning and highest in the afternoon. Temperatures of 33 and 35°C caused decline in pheromone titer to near zero in laboratory-reared and wild females, respectively. Calling behavior was not dependent on the presence of pheromone in the gland; it occurred in newly emerged females before pheromone could be detected and in females held at temperatures that inhibited pheromone production.

DOI:10.1093/ee/21.4.822

出版商:Oxford University Press    

年代:1992

数据来源: OUP