摘要:

Ovipositional patterns of adult female sweetpotato weevil,Cylas formicarius elegantulus(Summers), were examined in four laboratory experiments. In addition, survivorship of adult female weevils was assessed in one experiment. The life span of adult females averaged 75.8 ± 7.8 d, during which time females oviposited 122.0 ± 10.6 eggs. Preoviposition, oviposition, and postoviposition periods were 4.2 ± 0.2, 64.0 ± 6.5, and 7.6 ± 2.2 d, respectively. Maximum levels of oviposition occurred between 5 and 20 d after adult emergence from storage roots. Photoperiod affected fecundity; most eggs (about 75%) were laid during the scotophase, although some oviposition (about 25%) occurred during the photophase; oviposition occurred throughout the entire photoperiod. Disturbance of females during daylight reduced their levels of oviposition in daylight.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.545

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Plant lines with resistance (antibiosis or antixenosis or both), tolerance, or susceptibility to the spotted alfalfa aphid,Therioaphis maculata(Buckton), were selected from the cultivar OK08 for use in studies to describe the within-plant pattern of the aphid in the foliar canopy of alfalfa. Aphid counts and damage ratings were analyzed for each node (from the crown), and profiles of averages per node for each alfalfa line were prepared to illustrate within-plant patterns. Numbers of spotted aphids per node or per stem on susceptible and tolerant plants were significantly higher than on resistant plants. After 10 d of infestation, damage ratings averaged over nodes were significantly higher for susceptible plants than for those with resistance or tolerance. On all three lines, the spotted alfalfa aphid showed a clear preference for leaf blades over petioles or stems, and the greatest numbers were consistently found on nodes nearest the plant crowns. Little upward movement on stems was evident until damage to leaf blades of lower nodes had resulted in necrosis and leaf drop.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.551

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The population growth and spatial distribution of threeDalbulusleafhopper species were monitored on maize (Zea maysL.) from the seedling stage through maturation and senescence under greenhouse conditions.D. maidis, a maize specialist, completed two generations before maize senescence, with a significant population increase between the first and second generation. F1nymphs and adults moved upward on leaves (vertically) and from outer leaves into whorls (horizontally) soon after eclosion.D. gelbus, a gamagrass (wild maize relative) specialist also found on maize in the field, completed two generations on maize, but with a significant decrease in population size between generations.D. gelbusmoved upward on leaves as F1nymphs and adults, but not into whorls as frequently asD. maidis. D. quinquenotatus, a gamagrass specialist, produced one generation on maize, with population extinction occurring soon after adult eclosion on post-anthesis maize. Nymphs and adults remained within protective leaf sheaths of lower leaves, and did not move upward on leaves or into whorls. Some individuals moved onto tillers developing at the base of maize stalks. Utilization of the whorl is suggested to be critical in establishing a large second generation before maize senescence. Differences in the behavioral responses ofDalbulusspecies to maize phenology may explain, in part, the observed field host associations, and influence pest potential ofDalbulusspecies.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.556

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The influence of wind and site parameters on dispersal ofTrypodendron lineatum(Olivier) were evaluated using mark–recapture experiments. Beetles were released simultaneously from a windward and leeward side of a forest margin in a valley. With long-distance flight emphasized and no semiochemical-baited traps placed within 200 m of either release site, population movement (i.e., trap capture) from both release sites was predominantly downwind. Beetles also flew across the valley and were recaptured in traps on the opposite facing slope at a frequency of 38% of all recaptured beetles during the first four releases. Greater than three times as many beetles were recaptured within forested versus open settings, and is considered to be due mostly to the calmer wind conditions under the forest canopy. Such conditions appear to facilitate better flying and increased response to olfactory stimuli forT. lineatum. Management implications of these results are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.565

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The seasonal abundance ofLimothrips denticornisHaliday on spring barley (Hordeum vulgareL.) was examined during the growing seasons of 1987 and 1988 to aid in the development of an efficient sampling scheme. In 1987,78% of the immature population occurred during growth stage 10.4–11.1 (Feekes scale) (inflorescence three-quarters emerged-milk stage). In 1988, 81% of the immature population occurred during growth stage 10.54–11.2 (early milk stage–dough stage). The difference may be attributed to the drought conditions present in 1988, increasing the rate of plant development. When immature and adult counts were examined based on Julian day rather than on plant developmental stage, population trends occurred on similar dates in both years. Both adult and immature populations were concentrated on the top two leaf sheaths of barley regardless of plant development stage. There were significant differences between adult counts in quadrats within growth stages; a field edge effect was present both at the beginning and end of the season.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.577

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Laboratory experiments were conducted to determine the effect of soil texture and condition ofGalleria mellonellalarvae (infected withBeauveria bassiana, uninfected and alive, or uninfected and killed by freezing) on host-finding by the entomogenous nematodes,Heterorhabditis bacteriophoraandSteinernema carpocapsae, H. bacteriophorawas more motile thanS. carpocapsaein organic and fine sandy loam soils, but less motile in clay soil. In soil-filled tubes,H. bacteriophoraandS. carpocapsaeusually occurred more frequently near healthy hosts when healthy hosts were present in choice tests. When aBeauveria-infected host was included in a choice test, nematodes tended to occur more frequently at the host not infected withB. bassiana. This behavior may minimize antagonistic interactions between entomogenous nematodes andB. bassianain soil.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.582

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The development of intensive agricultural practices in areas that include cross-pollinated crops requires the introduction of large numbers of pollinating insects only during short flowering periods. The pollination efficacy of one pollinator,Osmia lignaria propinquaCresson, would be greatly improved if nesting populations could be successfully transported from crop to crop. Results of a 5-yr study that was focused on this subject are summarized as follows. Two studies involved moving individual nest blocks various distances within orchards, two additional experiments tested the possibility of moving bees nesting in small nest shelters greater distances during active nesting periods, and one study tested transport of bees nesting in large nest shelters constructed on flat-bed trailers. All of the transported bees in the first four experiments abandoned established nests immediately after they were moved, and none of these bees reestablished nesting within the confines of experimental plots. Conversely,>85% of females nesting in trailer–shelters continued to nest uninterruptedly after these large nest shelters were moved. Two additionalOsmiaspecies were also successfully transported when these large trailer–shelters were moved. A short discussion of nest orientation requirements expressed byOsmiais included.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.590

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The biology, effect on plant growth, and control of the azalea leafminer,Caloptilia azaleella(Brants), in container-grown nursery stock and landscape azaleas are reported. Azalea leafminer females survived for 5.3 d and oviposited 5.3 eggs/d. Fifty percent of the eggs were oviposited singularly on leaves. Egg development required 4.2 d at 25°C. Larval development appears to proceed through four and sometimes five instars. In the nursery and landscape, azalea leafminer populations peaked in January–March, but continuous generations occurred throughout the year. Nine species of parasitic Hymenoptera were reared from azalea leafminer larvae or pupae.Sympiesissp. (neardolichogastor) andParoligonerussp. emerged from azalea leafminer pupae and were the most abundant parasitoids. Azalea leafminer damage to azalea did not affect plant growth. Plant nutritional status and cultivar affected the infestation rate of azalea leafminer. Male response to pheromone production by female azalea leafminer was demonstrated.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.597

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

In a series of laboratory experiments, larvae ofSpodoptera frugiperda(J. E. Smith) were exposed to median lethal concentrations ofS. frugiperdanuclear polyhedrosis virus (NPV), and the survivors were reared to the adult stage and mated. Larvae, pupae, and, in later experiments, adults of the second-generation (F1) insects were then examined for signs of nuclear polyhedrosis. When natural isolates of NPV were fed to third instars in the first generation, total infection rates in F1S. frugiperdalarvae and pupae ranged from o to 0.89%. When fifth instars were fed virus in the first generation, infection rates in F1S. frugiperdaranged from 3.35 to 4.32% in larvae, from 0.75 to 2.08% in pupae, and from 8.05 to 9.92% in adults. NPV was selected for an increased rate of vertical transmission by isolation of virus from infected F1pupae. The selected NPV exhibited significantly (P<0.05) better vertical transmission than did the wild isolate. When fifth instars were fed selected virus in the first generation, infection rates in F1S. frugiperdawere 7.85–12.73% in larvae, 0.73–5.93% in pupae, and 9.72–10.45% in adults. Vertically transmitted NPV caused F1mortality mainly in early-instar larvae and in prepupae and pupae; there was little F1mortality in late-instar larvae or adults.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.603

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Laboratory experiments were conducted to measure the functional response ofPodisus maculiventris(Say) in a simplified arena. Predators were isolated singly for 24 h in 9-cm Petri dishes with either 1, 2, 4, 8, 12, or 16 third-instar larvae of Mexican bean beetle (Epilachna varivestisMulsant). Results showed a typical type II response, with up to 9 prey attacked when 16 were provided. Holling's disk equation was fitted to the data to give estimates of handling time and the maximum number of prey that could be attacked in 24 h. The results differed sharply with previous field measures of predation byP. maculiventris, indicating that attack rates in a simple laboratory arena are limited by different behaviors than are important in the field. As a result we suggest that measuring functional response must be done in an appropriate test arena if the results are to be used to predict the impact of the predator on field populations of prey.

ISSN:0046-225X    

DOI:10.1093/ee/20.2.610

出版商:Oxford University Press    

年代:1991

数据来源: OUP