摘要:

The role of leptine glycoalkaloids in resistance toLeptinotarsa decemlineata(Say) was studied withSolanum chacoenseBitt. clones that had been selected for extremes of leptine level. Three high-leptine (120–306 mg/100 g fresh weight) clones, one from each of three accessions, were compared with three low-leptine (0–51 mg/100 g) sib-clones for number of adults and feeding damage in the field, adult feeding rate on leaf disks, and larval development on detached foliage. Number of adults per plant on the six clones ranged from 1.5 for the clone with the highest leptine level (306 mg/100 g) to 37.5 for a clone lacking even a trace of these rare glycoalkaloids. There were also wide and significant differences among the six clones for adult feeding damage, adult feeding on leaf disks, larval development rate on detached foliage, and survival to adult eclosion. Differences between the high- and low-leptine clone from each accession were significant for all five resistance parameters, and these differences appeared to be directly related to the concentration of foliar leptines.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1057

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

(E)-11-tetradecenyl acetate and (Z)-11-tetradecenyl acetate have been identified as sex pheromone components of the banded sunflower moth,Cochylis hospesWalsingham. Identifications were made on the basis of capillary gas chromatography, electroantennogram measurement, and mass spectrometry data; the proportion ofE- andZ-isomers present in female abdominal tip extracts was ca. 5:1. In field experiments, traps baited with either component alone captured few or no target adults but isomeric blends ranging from 9:1 to 4:1 (E/Z) resulted in strong and specific attraction ofC. hospesmales. Additions of 5% (E)- or (Z)-11-tetradecen-1-ol to the basic attractant lures resulted in lower captures. Pheromone-baited traps were used to survey adult male populations at several southeastern Saskatchewan locations during 1984 and 1985. In 1984, high captures were observed at only one location, but in 1985 high captures were recorded at all locations.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1063

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Low-intensity radiation at night prevented diapause in larvae of the predatory midgeAphidoletes aphidimyza(Rondani) under environmental conditions (9:15 [L:D] photoperiod and 2l:l5°C [T:C]thermoperiod) that induced 100% diapause when “night” was dark. Diapause incidence was negatively related to radiation per unit area at levels<48 µW/cm2(50% of larvae within a 10-m radius.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1067

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Five entomopathogenic Hyphomycetes were tested under field conditions for biological control of brown planthopper,Nilaparvata lugens(Stål), in rice. Suspensions of conidia ofMetarhizium anisopliae(Metsch.) Sorokin,M. flavovirideGams&Roszypal,Beauveria bassiana(Bals.) Vuill., andHirsutella citriformisSpeare were applied at a rate of 4–5.1012conidia per ha. In addition,M. anisopliaeandPaecilomyces lilacinus(Thorn) Samson were applied as preparations of dry mycelium at a rate of 1.5–2 kg/ha. Mortality due to fungus infection ranged from 63 to 98% 3 weeks after application. There were no consistent differences between fungus species. The mycelium preparation sporulated on the plant and was as effective as the conidia suspension in infecting brown planthopper. Hyphomycetous fungi should be evaluated further for control of brown planthopper in rice.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1070

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Adult black vine weevils,Otiorhynchus sulcatus(F.), were fed ‘Totem’ strawberry or clone CL-5 of the wild beach strawberry,Fragarta chiloensis(L.) Duchesne weekly for 14 weeks after eclosion. Amounts of leaf provided were varied to give a food supply ranging from insufficient to abundant. In general, amount of leaf eaten increased, preoviposition period decreased, and number of eggs laid increased as leaf disk size increased. With equal food supply, feeding was less, preoviposition period was longer, and oviposition was less on CL-5 than on ‘Totem’. This indicated that resistance is due in part to less feeding on CL-5 than on ‘Totem’. However, preoviposition period was longer and fewer eggs were laid on CL-5 than on ‘Totem’ even when daily food intake was equal, indicating that factors in addition to antixenosis are involved in resistance of CL-5 to adult black vine weevil.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1074

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

The cotton tipworm,Crocidosema plebejana(Zeller), has periodically caused serious damage to seedling cotton in Southeast Queensland. An analysis of data over 11 years revealed that outbreaks of this pest are weather related. A heat/precipitation ratio (weather index) was calculated and compared with population levels of the tipworm. Outbreaks were strongly correlated to cool and wet weather during March–November, the principal growth period of the weed hostMalva parviflora(L.). Infestations were minor when conditions were dry. A prediction based on this index is compared with field infestation levels in 1984.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1078

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Differences in fall armyworm (FAW),Spodoptera frugiperda(J. E. Smith), larval preference for and development on fungal endophyte-infected (high incidence of infection) and uninfected (low incidence of infection) tall fescue,Festuca arundinaceaSchreb., at three relative leaf ages were examined. Neonate larvae significantly preferred older, uninfected leaves to equivalent age infected leaves and fed more upon them in paired choice tests. Fourth-instar preference and consumption were not affected by infection status of leaves of equivalent age in 6- or 16-h choice tests. Eight-day larval weights were significantly higher for larvae reared on infected older leaves. Percent wet weight of fescue leaves was significantly higher in infected older leaves. Water-soluble carbohydrate and crude protein content did not differ between infected and uninfected leaves at any leaf age, although crude protein was significantly higher in young leaves. Loline alkaloid content was significantly higher in infected leaves and decreased as leaf age increased. The data suggest that both larval age and relative leaf age affect FAW response to endophyte-infected tall fescue.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1083

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

This study demonstrates thatHylastes nigrinus(Mannerheim),Pissodes fasciatusLeConte, andSteremnius carinatus(Boheman) are vectors ofVerticicladiella wageneriKendrick, the causal agent of black-stain root disease of Douglas-fir,Pseudotsuga menziesii(Mirbel) Franco. These insects, known associates of diseased hosts, wound and create suitable infection courts in susceptible hosts, carry inoculum in the field, and transmit the pathogen to hosts under laboratory conditions. Root systems of 12-year-old Douglas-fir, cut during precommercial thinning, were infested by these insects and were susceptible toV. wageneriinfection for at least 7 months, confirming thatV. wagenerimay be introduced to thinned stands via these hosts. Male and female H.nigrinuscreated wounds suitable as infection courts on roots and root collars of crop trees for 1–2 years after precommercial thinning and may, therefore, introduceV. wagenerito thinned stands via these hosts. Insect-mediated transmission ofV. wagenerito Douglas-fir byH. nigrinusin the field is documented.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1090

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Development, natality, and survivorship rates of the aphidRhopalosiphum nymphaeae(L.) were measured at six constant temperatures with a photoperiod of 12:12 (L:D). The time required for development from first instar to adult ranged from 10.3 days at 18.3°C to 6.8 days at 30.6°C. No adults developed at 10 and 32.2°C. An additional instar was noted at 18.3°C. Longevity was highest at 10°C and lowest at 32.2°C. Natality rates ranged from 2.4 to 4.0 nymphs per aphid per day or 7.8–53.1 nymphs per female. Optimal tested temperatures forR. nymphaeaewere 21.1 and 26.7°C.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1096

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Populations of sugarcane delphacid,Perkinsiella saccharicidaKirkaldy, increased during summer months in Florida sugarcane to mean peaks of 7.5 per shoot in 1983 and 2.9 per shoot in 1984. In laboratory tests, mortality of all stages of sugarcane delphacid increased significantly at temperatures below freezing. Also, it was found that the egg stage was the most temperature-resistant stage from an extreme high of 45°C and low of −7.5°C. Our study, which included field population data, microclimate data, lethal temperature data, and long-term weather data, showed that sugarcane delphacid populations could be reduced by low winter temperatures in southern Florida sugarcane fields.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1100

出版商:Oxford University Press    

年代:1986

数据来源: OUP