摘要:

The effect of temperature on the rate of development and color patterns of two honey bee queen lines (black and yellow) was examined. The queens completed the postcapping period (last instar and pupal stages) in incubators maintained at temperatures corresponding with the natural range found in the brood nest: 30.5, 33.5, and 35.5∘C. The black line required significantly fewer accumulated degree-days for development than the yellow line at all temperatures. The queens from both lines had Significantly more yellow coloration on the integument when they completed the postcapping period at 35.5∘C than at 30.5∘C. These results suggest that brood nest temperatures playa more important role in the rate of development of queen lines and in the phenotypic expression of color patterns than has previously been recognized.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.364

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Mating by the fall armyworm,Spodoptera frugiperda(J. E. Smith), was studied in the laboratory. With the night cycle beginning at 2100 hours, 73–84% of the matings occurred between 2200 and 0300 hours. However, mating pairs were observed throughout the night. Most matings (80%) lasted longer than 45 min. Mean duration of mating averaged 130 min. Based on the number of spermatophores in the bursa copulatrix of mated females, female moths mated a mean of 3.7 times (range, 0–11) during their life span. Males mated a mean of 6.7 times (range, 0–15) during their life span. Matings by males were most frequent during the first three nights after their emergence. Although males mated throughout most of their adult life, the incidence of mating declined as the moths aged. The number of matings peaked at 25 and 30°C, with little mating at 10 or 15°C.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.371

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Symptom variants were subcultured from the NY-MAV isolate of barley yellow dwarf virus (BYDV) by transmission with single individuals ofSitobion avenae(F.). The aphids were allowed a 3-d acquisition access on infected oats, followed by a 1-h infection feeding access time on individual test plants. Infections were verified by ELISA. Two variant types were identified. Symptoms of one, the “notch” subculture, included the development of notches, leaf twisting, and intense reddish color. Those of the other, the “red” subculture, included only the intense red coloration. These symptom types were maintained through several successive transfers using 5–10 aphids and longer feeding infection times. Greenhouse and electronic monitoring experiments were conducted to evaluate the efficiency with which these variants were acquired from and transmitted to ‘Coast Black’ oats byS. avenae. Electronic monitoring showed thatS. avenaefed better on infected than on healthy plants, with faster and longer phloem contacts. Aphids acquired virus from the plants infected with the red subculture with greatest efficiency and made faster and longer phloem contacts on them than aphids fed on plants with the notch subculture, the source NY-MAV isolate, or on healthy plants. Extracts from plants infected with the red subculture also showed the highest ELISA values, suggesting a greater rate of replication.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.376

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Male Caribbean fruit flies,Anastrepha suspensa(Loew), exhibited two distinct calling periods under greenhouse conditions, one within the first hour of daylight and another during mid to late afternoon. In the laboratory, males called only during the afternoon. In the greenhouse, this afternoon calling period was not observed when flies were deprived of food for that day. High rates of calling were observed in the afternoon if flies were provided either a mixture of hydrolyzed torula yeast and cane sugar, or pure sucrose, but not if provided yeast alone, or deprived of food. Deprivation of sugar for 8 h resulted in a 30% reduction in calling rates in the afternoon, whereas such deprivation for 23 h (from late afternoon to midafternoon) nearly eliminated calling during that period. Male Caribbean fruit flies kept in cages with green, ripe, or overripe guava fruit also exhibited calling (35–45%) near dawn, but only those flies kept in cages with overripe fruit called in the afternoon. Such a difference is likely due to males feeding on the surface of overripe fruit.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.382

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Percentage hatch, chewing predation,Chrysopasp. predation, other sucking predation, and parasitism byTrichogrammasp. of egg masses of first-generationOstrinia nubilalis(H¨bner) were estimated in spring chisel plow, ridge tillage, and no-tillage maize,Zea maysL., in southeastern Minnesota during 1986 and 1987. Tillage plots were split with and without terbufos application and with and withoutBacillus thuringiensis-permethrin application in all combinations. Egg masses from laboratory rearedO. nubilaliswere exposed to natural enemies in the field eight times during the oviposition period of first-generationO. nubilalis, and population densities ofColeomegilla maculataDeGeer were estimated. Parasitism was 0.6% and predation was low during 1986. During 1987, chewing predation was highest in the chisel-plow system and lowest in the no-tillage system;Chrysopasp. predation was lowest in the chisel-plow system and highest in the no-tillage system.C. maculatapopulation densities were highest in the chisel-plow system and lowest in the no-tillage system, and chewing predation was positively related toC. maculatadensity. Predation by other unknown chewing predators was also higher in the chisel-plow system and lowest in the no-tillage system. The inverse relation between chewing andChrysopasp. predation was probably related to species specific responses to the tillage environments.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.388

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

This study was conducted to assess potential biases associated with three methods of calculating percentage parasitism of gypsy moth,Lymanttia dispar(L.), pupae byBrachymeria intermedia(Nees). We determined the timing of four processes: (1) recruitment of gypsy moth (host) larvae to the pupal stage, (2) recruitment (oviposition) ofB. intermediato its immature stage, (3) losses of hosts from the pupal stage because of mortality or adult emergence, and (4) losses of immatureB. intermediabecause of mortality or adult emergence.B. intermediaemerged after most unparasitized pupae had died or after moths had emerged. As a result, the proportion of pupae in samples that were parasitized increased with time. Sample percentage parasitism peaked late in the season and overestimated levels of stage-specific parasitism. Parasitism extended the residence time of parasitized pupae, with the result that they were available to predators for a longer period of time than un parasitized pupae and suffered a higher level of predation. Examination of pupal exuviae at the end of the season, therefore, underestimated the effect ofB. intermedia. No biases were observed that affected estimation of percentage parasitism through the direct measurement of host and parasitoid recruitment. Of the three methods studied (percentage parasitism in samples, examination of exuviae, and measurement of recruitment), direct measurement of host and parasitoid recruitment appears to be the best method for measuring the effect ofB. intermediaonL. dispar.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.394

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Coccygomimus disparis(Viereck) attacked most of the 16 novel hosts species offered in laboratory trials and produced viable adults in 7 of these species. The manner of host presentation significantly affected host recognition and acceptance; immobilized or concealed pupae were attacked more readily than writhing or exposed pupae. In a choice experiment,C. disparisused concealed greater wax moth pupae primarily for oviposition. Exposed wax moth pupae offered simultaneously were used byC. disparismore often for host feeding. Parasite preference for and improved efficiency with cocooned, concealed, or immobilized hosts suggests that butterflies and other lepidopteran species with exposed pupae will be used infrequently for reproduction. In contrast, it is predicted that several endemic defoliator pests are likely to become new host species, shouldC. disparisbecome established in Minnesota. Implications for sampling gypsy moth,Lymantria dispar(L.), are discussed. Attacks on gypsy moth should differ with the orientation and degree of concealment of pupae. Parasitism plus host feeding could cause more mortality to host populations than is disclosed by rearing.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.401

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Studies were conducted at eight locations in Ingham County, Michigan, during 1989–1990 to determine the within-field distribution of European corn borer,Ostrinia nubilalis(H¨bner), larval parasitism.O. nubilalislarval sampling was conducted at multiple locations on three transects across large 1st-yr corn fields during the F1and F2generations. Plants were destructively sampled to determineO. nubilalisabundance and larvae were returned to the lab to determine parasitism.Eriborus terebrans(Gravenhorst) (Hymenoptera: Ichneumonidae) was the dominant parasitoid ofO. nubilalisin the sampled fields, accounting for 92.5% of the F1and 99.2% of the F2parasitism during 1989; and for 92.2% of the F1and 99.1% of the F2during 1990. Average parasitism byE. terebrans(n= 4 fields) was 4.9 and 18.7% of F1, 10.2 and 9.1% of F2larvae during 1989 and 1990 respectively. The maximumE. terebransparasitism observed (37.4%) of theO. nubilalislarvae in one field (F11990), is the highest level reported for this species in the Midwest. Parasitism byE. terebransduring the F1generation was greater along field margins than in field interiors in most fields during both years. During 1990,O. nubilalislarvae near wooded edges had significantly higherE. terebransparasitism than those near nonwooded edges or field interiors. In the F2generation, parasitism did not vary significantly from field margins to field interiors in either year. There was no consistent relationship betweenO. nubilalislarval density per infested plant andE. terebransparasitism. These data suggest that local landscape structure, including proximity of particular noncrop habitats, plays an important role in the effectiveness of this natural enemy.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.409

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

The distribution, dispersal, and population growth of an ectoparasitic nematode,Noctuidonema guyanenseRemilIet&Silvain, were studied on mating pairs ofSpodoptera frugiperda(J. E. Smith) in the laboratory. Nematode populations were the greatest on terminal abdominal segments of wildS.frugiperdamales. Eggs and neonates were predominant on abdominal segments eight to ten, whereas juveniles were distributed widely along a host's abdomen and thorax. Although female nematodes moved from infested male moths to noninfested female moths within 15 min after initiation of host mating, male and immature nematodes often did not transfer until 1.5–2.0 h after host copulation began. Nematodes migrated anteriorly to the fifth abdominal segment of new hosts in 4–7 h. Forty-eight percent of the host-matings resulted in the transfer of an average of 5.3 nematodes to new hosts. Populations ofN.guyanenseon newly infested female moths increased to an average of 400 nematodes within 176 h after the initiation of mating by hosts. About 80% of the nematodes that transferred to new hosts were juveniles.

ISSN:0046-225X    

DOI:10.1093/ee/21.2.417

出版商:Oxford University Press    

年代:1992

数据来源: OUP

ISSN:0046-225X    

DOI:10.1093/ee/21.2.422

出版商:Oxford University Press    

年代:1992

数据来源: OUP