摘要:

When mated femaleT. urticaewere allowed to feed freely on individual variegated leaves ofEuonymus japonica, they preferred to forage on the green tissue. Green tissue of variegated leaves had 1.6% phenolics on a dry-weight basis, which represents 18.4% more than yellow tissue. Over the 9-d observation period, females on variegated leaves maintained the same fecundity as a cohort feeding on entirely green leaves with average phenolic content only 5.6% greater than that of variegated leaves. These results contrast with those where herbivores avoided green tissue of a variegated plant because of more substantial (140.6%) differences in the phenolic content of green and variegated tissue. We conclude that in the absence of a phenolic defense, the potential for pest injury is acute in variegated plants. On an undefended variegated plant, feeding is focused on the diminished green area that is critical for growth. The nature of phenolic production in plant tissue in relation to the resource-balance theory of plant defense, and its effectiveness in variegated plants is discussed.

DOI:10.1093/ee/21.4.827

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Artemia salina(L.) specimens were fed ad libitum toToxorhynchites splendens(Weidemann) larvae held at concentrations of 0-12‰ sea salt. Above 8‰, salt concentrations adversely affected both pupal weight and mean larval developmental period significantly. Adverse effects on postlarval stages included an expanded pupal period and decreased reproductive capacity. When nectar feeding was discontinued 24 h after the onset of reproduction, overall egg production was higher for adults resulting from larvae fedA.salinaat 8‰ than for adults resulting from larvae fed mosquitos in deionized water. Sugar deprivation significantly decreased both the survival and reproduction ofT. splendensreared at 10 and 12‰ salt more than other treatments.A. salinaappears to be a prey candidate for mass production ofT. splendensat saline levels<10‰. Reproductive potential and rate of increase were higher for predators given brine shrimp in 8‰ salt water than for those given mosquito larvae in deionized water.

DOI:10.1093/ee/21.4.832

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

In laboratory choice and no-choice tests, an aqueous extract of tansy,Tanacetum vulgareL. (Compositae), reduced feeding on cabbage leaf disks by imported cabbageworms,Artogeia(=Pieris)rapae(L.). Imported cabbageworms reared on cabbage leaves treated with tansy extract took longer to develop to pupation, and pupae weighed less than insects reared on control leaves. In oviposition choice tests, imported cabbageworms laid three times as many eggs on control (water-sprayed) cabbage plants as on tansy-treated plants. Diamondback moths,Plutella xylostella(L.), laid more than twice as many eggs on control as on tansy-treated plants. In both spring and fall cabbage field trials, 1 and 5% tansy treatments reduced insect numbers significantly on at least some dates. Insect damage ratings at harvest were significantly lower for tansy-treated plants than for plants treated with either water or water plus surfactant, although higher than damage ratings forBacillus thuringiensis-treated plants. The surfactant used with the tansy treatments, 1% (vol/vol) Triton B-1956 (now Latron B-1956), reduced cabbage head weights substantially in water plus surfactant control treatments compared with the water-only treatment.

DOI:10.1093/ee/21.4.837

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Cytological analysis of wheat infested by the Hessian fly,Mayetiola destructor(Say), indicated that on susceptible plants, virulent larvae (biotype L, virulent to resistance genes H3,5,6,7/8) caused a generalized increase in cuticular-membrane permeability of cells in the lower leaf sheath. On resistant plants, feeding by avirulent larvae (biotype GP, no genes for virulence) resulted in localized responses. This suggests that plant responses limited the ability of avirulent larvae to elicit generalized changes in cell permeability. Analyses of plant protein patterns by polyacrylamide gel electrophoresis and immunoblots indicated that separate changes in protein metabolism occurred in susceptible versus resistant wheat in association with Hessian fly infestation. In susceptible wheat, ribulose-l,5-bisphosphate carboxylase (Rubisco) increased in the lower leaf sheath in association with infestation. In resistant wheat (cv. Caldwell, H6gene for resistance), proteins of low molecular weight appeared in the lower leaf sheath in association with infestation by avirulent larvae. Protein changes associated with infestation were not elicited by physical wounding of plants. Protein changes detected in resistant wheat infested by avirulent larvae (biotype GP) did not appear when the plants were infested with virulent larvae (biotype L). Results support the hypothesis that hypersensitivity is the phenotypic basis of resistance in the Hessian fly-wheat interaction and involves “recognition” of an avirulence gene product or process.

DOI:10.1093/ee/21.4.845

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Collections of volatile chemicals emitted from flowers of night-blooming jessamine,Cestrum nocturnumL., yielded three principal chemicals; benzaldehyde, benzyl acetate, and phenylacetaldehyde. Female cabbage looper moths,Trichoplusia ni(Hübner), exhibited upwind oriented flight and contact with dispensers that released an artificial blend of synthetic compounds similar to the natural blend from jessamine flowers. Observed behaviors in response to phenylacetaldehyde alone were not Significantly different from those to the complete blend, although moths also oriented to benzyl acetate. Based on these results, phenylacetaldehyde alone may provide optimum attraction of cabbage looper moths to the flowers and to artificial lures. The plants displayed a diel periodicity in the release of these compounds coincident with the diel pattern of feeding activity of cabbage looper moths. Moth feeding occurs principally at and immediately after dusk, and the production of the floral odor peaked in the first 2 h of the scotophase.

DOI:10.1093/ee/21.4.854

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Since 1986 perizin has been used in many European countries to combat the miteVarroa jacobsoni, a parasite of the honeybee. We have studied the long-term presence of coumaphos, the active ingredient of perizin, by analyzing honey and wax for residues. We distinguished between the direct transfer of coumaphos into wax by contamination during treatment and the indirect transfer through wax production by bees. To study the indirect transfer, we treated colonies with perizin and removed the combs, thus forcing the bees to produce new wax. The newly produced wax and honey were analyzed for the presence of coumaphos. Wax from colonies that had not been treated with perizin for 6 mo and up to 18 mo still contained coumaphos (7 and 1 μg/g wax, respectively). Moreover, newly produced wax from the colonies that had not been treated with perizin for 6 mo also contained coumaphos (≍17% of the amount found in old wax). No residues were found in honey. Only small amounts of coumaphos (±l‰ of the amount administered) were found in newly produced wax when colonies were fed a perizin-sugar solution. The largest amounts of contamination were found in the first samples secreted; samples taken 3-4 d after application contained only 1-5% of the amount secreted on the 1st d. Coumaphos is transferred mainly into the wax directly as a consequence of the application of perizin to combs, and the acaricide is persistent in the wax.

DOI:10.1093/ee/21.4.860

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

We demonstrate that the red imported fire ant,Solenopsis invictaBuren, is attracted to electric fields. Attraction is directly proportional to field strength (determined by voltage and distance between charged disks) for both direct (DC) and alternating (AC) current. Direct and alternating current attracts approximately equal numbers of ants at the same voltage and distance between charged disks. The only difference observed between the two types of current is that ants leave AC-charged disks at a much lower rate when the circuit is opened. We have not yet determined how or why ants detect and are attracted to electric fields. This attraction results in problems when ants invade, short-circuit, and destroy electrical equipment.

DOI:10.1093/ee/21.4.866

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Dung from cattle injected with a single dose of either 20 μg ivermectin/kg of body weight or the recommended therapeutic dose of 200 μg/kg was bioassayed in the laboratory weekly for 10 wk with the horn fly,Haematobia irritans(L.), and two species of dung-burying Scarabaeidae,Euoniticellus intermedius(Reiche) andOnthophagus gazella(F.). Dung from the same cattle was also bioassayed for 6 wk with two species of predaceous Staphylinidae,Philonthus flavolimbatusErichson andP. longicornisClark. Emergence of adult horn flies was reduced 42.3–100% for 6 wk when reared on dung from cattle that received the 20 μg/kg dose and compared with emergence of horn flies reared on dung from untreated cattle. When reared on dung from cattle that received a dose of 200 μg/kg, horn fly emergence was reduced 78.7–100% for 8 wk. The two treatment levels had no apparent effect on the production of brood balls by either species of dung beetle. However, emergence of adultE. intermediusandO. gazellafrom brood balls made with dung from cattle that received the 200 μg/kg dose was reduced for 1 and 2 wk, respectively. There was no reduction in the emergence of adults of either beetle species at the 20 μg/kg dose. The number ofP.flavolimbatusprogeny reared on dung from cattle that received the 200 μg/kg dose was reduced for 1 wk compared with the number of progeny reared on untreated dung. There was no apparent effect on the number ofP. longicornisprogeny when reared on dung from cattle that received the 200 μg/kg dose of ivermectin. Dung from cattle that received the 20 μg/kg dose had no apparent effect on the number of progeny of either predator species.

DOI:10.1093/ee/21.4.871

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

The second generation ofAnisopteromalus calandrae(Howard) collected from commercial stored com in South Carolina was reared at constant temperatures of 20, 25,30, and 35°C at 63% RH and a 12: 12 (L:D) photoperiod. Hosts were medium to large larvae ofSitophilus zeamaisMotschulsky reared on corn (21–23 d old at 25°C, 63% RH). Daily production of viable progeny, sex ratio, adult female survivorship, and development time were measured to calculate net reproductive rate (Ro), generation time (T), intrinsic rate of increase (Rm), and female adult life expectancy. Female longevity was greatest at 20°C (14.5 d median) and shortest at 30 and 35°C (6 d). Median female development time ranged from 44 d at 20°C to 10 d at 35°C. Mean number of progeny produced per female over her lifetime increased from 10.4 at 20°C to 42.6 at 35°C. Progeny sex ratio was much lower at 20°C (33% female) than at the other temperatures (63–71% female). Intrinsic rate of increase was lowest at 20°C (0.028 female per female per day) and greatest at 35°C (0.250),Roincreased from 4.5 female per female at 20°C to 27.7 at 35°C, andTdecreased from 53.5 to 13.3 d.

DOI:10.1093/ee/21.4.877

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Fall armyworm,Spodoptera frugiperda(J. E. Smith), larvae were collected from 24 May to 28 August 1990 and from 20 May to 17 June 1991 to determine parasitoid distribution of fall armyworm on resistant and susceptible com genotypes. Resistant corn genotypes were ‘MpSWCB-4’ and ‘Pioneer X304C’ and susceptible genotypes were ‘Pioneer 3192’ and ‘Cacahuacintle X’s'. In 1990,Cotesia marginiventris(Cresson) was the most prevalent parasitoid in early season, parasitizing 34% of fall armyworm larvae, and it continued to be present in low numbers throughout the summer. On only one collection date (24 May 1990) did corn genotype have a significant effect on parasitism rates. On that date, significantly moreC. marginiventriswere reared from hosts obtained from resistant corn genotype ‘MpSWCB-4’ than from the other three genotypes. In 1991,Archytas marmoratus(Townsend) was the most abundant parasitoid, attacking an average of 13.6% of fall armyworm recovered. Corn genotype had a significant effect on the incidence of parasitism throughout 1991. Fall armyworm collected from the susceptible genotype ‘Pioneer 3192’ were parasitized significantly less frequently (8.3%) than were the larvae collected from the susceptible corn genotype ‘Cacahuacintle X’s' (9.8%) or the resistant genotype ‘MpSWCB-4’ (9.6%).

DOI:10.1093/ee/21.4.888

出版商:Oxford University Press    

年代:1992

数据来源: OUP