摘要:

Pupal development times and thermal unit requirements, daily adult eclosion patterns, and the durations of phases of emergence of the Mexican rice borer,Eoreuma loftini(Dyar), adult sexes were observed under reversed photoperiodic and thermoperiodic conditions. Female pupae required fewer days and thermal units for development than did males. Both sexes eclosed early in the scotophase; eclosion of adult males and females was complete within ≍ 1.7 and 4.5 h of last light, respectively. Newly emerged males required less time than females to inflate and dry their wings and less time for the entire emergence process (eclosion to wings dried and folded in a normal resting position). The temporal patterns of emergence suggest that efforts to observe emergence in sugarcane fields should be concentrated in the early scotophase. The short duration of the emergence process will limit the time during which newly emerged moths can be identified. Therefore, cage studies of emergence may offer a greater likelihood of success than studies relying on direct observation, especially under the usual conditions of low E. loftini population intensity and high crop biomass.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.76

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Adult females of the silverleaf whitefly,Bemisia argentifoliiBellows&Perring, and the sweetpotato whitefly,B. tabaci(Gennadius), were given access to three different host plants in choice and no-choice experiments to determine if oviposition preference could account for field observations of host use. The experimental host plants were zucchini, which is a preferred host for both species; sugar beet, which is not favored by either species; and cabbage, which is preferred byB. argentifoliiand rarely used byB. tabaci. In choice trials, both whitefly species laid the greatest proportion of eggs on zucchini. The lowest proportion of eggs laid byB. argentifoliiwas on sugar beet, whereasB. tabacilaid its lowest proportion on cabbage. The proportion of eggs laid on cabbage byB. argentifoliiwas significantly greater than th.at laid byB. tabaci. In bihourly counts, females of both whitefly species were found on each host in approximate proportion to their oviposition choice. In no-choice trials both whitefly species laid approximately the same numbers of eggs on zucchini; yet on cabbage and sugar beet,B. argentifoliilaid significantly more eggs. An additional experiment revealed thatB. tabaciwould oviposit on cabbage to the same degree asB. argentifoliiif the leaf surface was rubbed smooth.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.88

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

An oviposition profile of the first 4 d after mating was constructed for the Mexican rice borer,Eoreuma loftini(Dyar). Effects of pupa] weight on potential and realized fecundity were examined by comparing the numbers of oocytes contained in newly emerged females to numbers of oviposited eggs and retained oocytes of females allowed to oviposit for 4 d. Oviposition was greatest on the second night after mating and least on the fourth night. Pupal weight did not influence the percentage of the egg complement that was oviposited in 4 d, but accounted for 81 and 74% of the variation in the size of egg complements among newly emerged moths and moths that oviposited for 4 d, respectively. Slopes of these regression equations were not different and indicated thatE. loftinifemales contain a full egg complement at eclosion. Realized fecundity was also related to pupal weight at 1–4 d after mating. Pupal weight explained an increasing proportion of observed variation in fecundity with increasing oviposition time, from 17% after 1 d to 61% after 4 d. Implications of these findings to future studies are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.94

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Acetate selection and biochemical tests were used to characterize the gram positive, spore-forming bacteria associated with samples of straw and sawdust used as bedding in outdoor calf hutches. Bedding samples were collected from 25 calf-occupied hutches during 6-wk periods. More than 7,100 isolates representingBacillus thuringiensis(4,616),Bacillus sphaericus(1,390), andBacillus megaterium(1,182) were recovered. Fourteen biochemical types ofB. thuringiensiswere identified; these includedgalleriae, kurstaki, thuringiensis, israelensis, sotto, darmstadiensis, tenebrionis/morrisoni, dendrolimus, andindiana. Of these,tenebrionis/morrisoniandisraelensiswere associated most often with tulip poplar and maple sawdusts, respectively. Tulip poplar sawdust supported more diverseB. thuringiensisbiochemical types than other types of sawdust or straw.B. thuringiensiswere prevalent in calf-hutch bedding throughout 6-wk periods.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.99

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Occurrence, timing within the scotophase, and duration of mating, as well as timing within the scotophase of calling by females, were observed in the laboratory for pairs of all age combinations of 0- to 5-d-old male and femaleEoreuma loftini(Dyar). Also, occurrence of mating of 1- to 5-d-oldE. loftinifemales was examined on mating stations in commercial sugarcane (Saccharumspp.). Percentage of mating moths in the laboratory ranged from 67.3 (4 d old) to 78.7% (1 d old) for females and from 56 (0 d old) to 81.3% (5 d old) for males. Occurrence of mating generally increased with male age. Mating was least likely to occur when one sex was very old and the other very young. Females called earlier, and both sexes mated earlier as age increased. Duration of mating also was influenced by age of either sex, but these differences were small relative to the mean total duration of mating. Differences in female age seldom resulted in large differences in occurrence of mating on mating stations, but when differences occurred, younger females were more often mated than older females. Changes in temporal patterns of sexual response and receptivity of males and females, respectively, probably caused the observed effects of age on mating occurrence.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.105

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Emergence of adultStethorus punctum punctum(LeConte) from overwintering sites in apple orchards was examined for 3 yr in Adams County, Pennsylvania. Emergence during the spring in cages placed over overwintered individuals occurred between 100 and 300 degree-days (DD) when temperature units were accumulated beginning 1 March. Fifty percent emergence occured at 210 DD5°C. Emergence was 2.3, 46.7, and 95.8% complete by the half inch green, pink, and the petal fall stages of ‘Yorking’ apple development, respectively. Most adults emerged on days of average, minimum, and maximum air temperatures of 15–20, 5–15, and 20–30°C, respectively. Temperatures in overwintering habitat were similar to ambient air temperature. Counts in the tree canopy were highly correlated with capture in the emergence cages in a warm year, but were too low to relate to capture in the other two cooler years. Capture of adults on yellow sticky boards was an efficient monitoring method; first capture occurred at 20–30% emergence. Yellow traps were more effective than white, and addition of ammonium carbonate did not significantly increase capture with yellow traps, but inhibited capture with white traps.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.110

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Ethanol extracts from the bodies of male or female American cockroaches,Periplaneta americana(L.), repel conspecifics of all ages and sexes from shelters during the photophase. Full repellency is obtained above a dosage of 1.6 cockroach equivalents per shelter. The repellent is endogenously produced, is distributed throughout the bodies of individuals of both sexes, and is effective against at least four other species of cockroaches of diverse phylogenetic relationship, including the German cockroach,Blattella germanica(L.). There was no evidence that the repellent is released by living insects as an alarm pheromone. The active materials (identified elsewhere as unsaturated fatty acids) differ from the proteinaceous dispersion-inducing substance produced by living German cockroaches. There was no evidence that the repellent reported here was released from living cockroaches, even at very high population densities. Cockroaches were repelled, however, by intact and ruptured corpses. The repellent may function as a cue for avoiding areas where other cockroaches have died. A literature review suggests that unsaturated fatty acids may elicit avoidance of dead conspecifics across wide phylogenies of invertebrates.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.116

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

For 3 yr (1989–1991) we examined effects of different integrated pest management (IPM) programs on populations of mites in an apple orchard in Nova Scotia, Canada. The stage 1 IPM program involved pest monitoring and application of insecticides (phosmet, pirimicarb,Bacillus thuringiensisvar.kurstakiBerliner + one-tenth the recommended rate of cypermethrin) known to be harmless or slightly harmful to the phytoseiid predatorTyphlodmmus pyriScheuten. With the stage 2 program, most insecticide applications were replaced by alternatives such as insecticidal soap, insect pathogens, and insect growth regulators. In stage 1 and stage 2 plots, apple scab,Venturia inaequalis(Cke.) Wint., was controlled either with captan, a fungicide that is harmless to phytophagous mites andT. pyri, or with metiram, a fungicide that is slightly harmful to phytophagous mites and moderately harmful toT. pyri. In June and July 1989, densities of European red mite,Panonychus ulmi(Koch), and apple rust mite,Aculus schlechtendali(Nalepa), were too high (maximum 7.6 to>100 per leaf) to be controlled by the low numbers ofT. pyri(<0.1 per leaf) present in the orchard. An early August application of the miticide propargite in stage 1 plots or hexythiazox in stage 2 plots caused populations ofP ulmiandA. schlechtendalito decline to 0 per leaf without reducingT. pyripopulations. In 1990 and 1991, mite counts in stage 2 plots did not differ with fungicide regime. In stage 1 plots, however, counts ofP. ulmiandA. schlechtendaliwere higher and counts ofT. pyri, but not the stigmaeid predatorZetzellia mali(Ewing), were lower with metiram than with captan. Biological control was effective in stage 2 plots and all captan plots: maximum counts ofP. ulmiandA. schlechtendaliwere<1.5 per leaf and 6 per leaf, respectively. Maxima were higher, but still subeconomic, in the stage 1 metiram plots: 5 per leaf forP. ulmiand 9 per leaf forA. schlechtendali. Additive toxic effects of insecticides and fungicides onT. pyri, the possible contribution ofZ. malito biological control despite competition withT. pyri, and recommendations for integrated mite control are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.125

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Laboratory bioassays were conducted to determine pathogenicity of five entomopathogenic nematodes from the generaSteinememaandHeterorhabditisagainst melonworm,Diaphania hyalinata(L.).S. carpocapsae(Weiser)(Mexicanstrain) was the most pathogenic nematode species, followed byH. bacteriophora(Poinar),S. feltiae(Filipjev),S. anomali(Kozodoi),andS. glaseri(Steiner), respectively. The LC50forS. carpocapsae(Mexican) was 39.9 infective juveniles per milliter. The rate of nematode invasion into insects was proportional to the overall pathogenic effect of the various nematodes. The level of insects mortality and infectivity(the number of nematodes invading the insect) were directly related to exposure time. First instars and pupae were significantly less susceptible to S.carpocapsaeinfection than older larvae and prepupae. The number of nematodes found in the hemocoel increased with larval age. Mortality and infectivity were inversely related to nematode size. In field trials, survival ofS. carpocapsae(All strain) on squash plant foliage was reduced to 0.77% within 40 h in a trial under high humidity conditions and to 0.25% after 18 h in a trial under moderate humidity conditions. Field applications of 5 billion nematodes per hectare produced infection rates of 52-55%.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.143

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The vertical movement, persistence, and activity of four isolates of entomopathogenic nematodes,Heterorhabditis bacteriophoraPoinar (Oswego),Heterorhabditis bacteriophoraPoinar (NC),Steinernema carpocapsae(Weiser) (NY001),and an undescribedSteinernemaspecies (NY008-2E), were evaluated for 24 mo at field locations in northern New York. Nematodes were released into three alfalfa fields naturally infested with alfalfa snout beetle,Otiorhynchus ligustici(L.). Each field differed in soil type and soil textural composition: silt loam, sandy loam, and loamy sand. Nematodes were recovered from soil using trap insects,Galleria mellonellalarvae, and their vertical distribution was monitored at 5-cm intervals to depths of 20 cm forSteinernenaspecies and 35 cm forHeterorhabditisspecies.All nematodes persisted (no significant reduction in percentage of infection ofG. mellonella) for 6 mo after the initial application in all soil types. However, by the end of the second growing season (17 mo after application), all nematodes showed significant reductions in infection rates ofG. mellonellaexceptH. bacteriophora(Oswego) which showed high levels of infection for 24 mo. Nematode vertical movement was affected by soil type and varied by isolate.S. carpocapsae(NY00l)andSteinernemasp. (NY008-2E) remained primarily in soil depths<15 cm, whereas both heterorhabditids dispersed to soil depths of 35 cm. Vertical movement ofH. bacteriophera(Oswego) was greatest in loamy sand and vertical movement ofSteinernemasp. (NY008-2E) was greatest in sandy loam. Percentage of infection of G.mellonellabyH. bacteriophora(Oswego) andS. carpocapsae(NY00l)was significantly correlated with rising soil temperatures in early spring.H. bacteriophora(Oswego) andS. carpocapsae(NYOOl)infectedG. mellonellalarvae in the field at soil temperatures between 15 and 18°C.Steinernemasp. (NY008-2E)infectedG. mellonellalarvae in the field at soil temperatures between 13 and 15°C.

ISSN:1754-5692    

DOI:10.1093/ee/24.1.149

出版商:Oxford University Press    

年代:1995

数据来源: OUP