摘要:

The response of sunflower (Helianthus annuusL.) to feeding damage by insects and to mechanical damage was studied in the leaves of the plant. One class of chemicals found to accumulate after stress, the coumarins, was quantified by analysis with HPLC. Sunflowers were damaged by sunflower beetle,Zygogramma exclamationis(F.), flower thrips,Frankliniella tritici(Fitch), or by mechanical puncture. Scopoletin concentrations were 252μg/g fresh weight at 22 d and ayapin concentrations were 165μg/g at 25 d, in beetle-damaged sunflowers. The scopoletin concentration was three times higher and the ayapin concentration five times higher than that in control sunflowers (P<0.05). Thrips induced significantly higher scopoletin concentrations at 11 d and higher ayapin concentrations at 16 d after feeding began (P<0.05). Mechanical damage induced significantly higher scopoletin concentrations 11 d after the damage was inflicted. The initial type of induced response in sunflower was of the “halo type”; that is, highest in successive concentric circles approaching the wound site. A 3-mm puncture induced coumarins within a diameter of at least 1 cm at 1 wk. A systemic response may have begun after the first week. To study the effects of coumarin on host acceptability to the sunflower beetle, coumarins were applied to unstimulated sunflower leaf disks. Beetles chose between treated or control disks in a closed arena. The control disks were preferred over treated disks when 20μg/ml of scopoletin or coumarin and 100μg/ml of ayapin or scopoletin were sprayed onto leaves. The coumarins are apparently induced by insect feeding and slowly increase in sunflower tissue. Induced coumarins may subsequently deter additional feeding of sunflower beetles.

DOI:10.1093/ee/20.4.1166

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Adults of several species of cucumber beetles compulsively eat bitter triterpene cucurbitacins, but it is unknown if their larvae exhibit the same behavior. The affinity of spotted cucumber beetle larvae to cucurbitacins was tested by performing feeding choice experiments using bitter (Cucurbita andreanaNaudin) and nonbitter (C. palmeriBailey) root cuttings and nonbitter roots ofCucumis sativasL. coated exogenously with cucurbitacin B. Within a 24-h period, larvae ate significantly more of the bitter than the nonbitter roots in both experiments.

DOI:10.1093/ee/20.4.1173

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The effects of temperature, food type, and sucrose feeding on longevity of house flies,Musca domesticaL., were studied. Longevity decreased with increasing temperature. Flies fed cattle manure, poultry manure, or nothing had similar lifespans, which were lower than lifespans of flies fed milk. Sucrose increased longevity for flies on all diets except milk. Addition of poultry feed to a diet of poultry manure also increased longevity. Variation in longevity was highest for flies that were fed milk or sucrose. The intercept (but not the slope) of the relationship between longevity and temperature was affected by diet, indicating that the overall level of the response of fly longevity to temperature was governed by diet. Sugar feeding was detected in 12% of female flies captured in three dairies, and occurred at similar levels among dairies.

DOI:10.1093/ee/20.4.1176

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Clover stem borers,Languria mozardiLatreille, were reared at constant temperatures ranging from 12° to 39°C on artificial diet. Development times were inversely proportional to temperature between 12 and 35°C and increased above 35°C. The duration of preimaginal development (egg to adult) varied from 90.5 d at 15°C to 20.9 d at 35°C. The optimal temperature for development was about 30°C. Parameter values were reported for the Weibull distribution fitted to mean normalized development times (r2= 0.993–0.998) and for a biophysical model fitted to development rates of each stage (r2= 0.991–0.999). A six parameter model with high- and low-temperature inhibition was derived for the egg stage. Four parameter models with high-temperature inhibition were proposed for development rates of the larvae and pupae. The predictions of these models, combined with estimates of oviposition rates, should facilitate development of efficient sampling protocol for all stages of clover stem borers.

DOI:10.1093/ee/20.4.1181

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The host specificity ofEustenopus villosus(Boheman) was studied in the laboratory using field-collected adults from Greece and overwintered progeny of these adults. No-choice and two-choice host specificity tests were carried out in the laboratory. Thirty-four plant species, in addition to yellow starthistle (Centaurea solstitialisL.) (as the control) from Greece and the United States, were tested. Under no-choice test conditions in the laboratory, adults showed to some degree a rather broad feeding spectrum but with heaviest feeding on yellow starthistle. Oviposition was restricted to some species in the genusCentaurea, with heaviest oviposition on yellow starthistle. Under two-choice conditions (test plant caged with yellow starthistle control), oviposition occurred only on yellow starthistle. The literature on field hosts and host specificity tests indicate a high level of larval host specificity to yellow starthistle. A laboratory study showed that the combined effects of adult and larval feeding on yellow starthistle can reduce seed production by 98.8% under laboratory conditions; this also indicates that the species has excellent potential as a biological control agent.

DOI:10.1093/ee/20.4.1187

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The longevity and fecundity of the parasitoidDiglyphus intermedius(Girault) and the host mortality induced by the parasitoid were studied at five constant temperatures from 15.6 to 31.1°C. Third instars ofLiriomyza trifolii(Burgess) were provided as hosts. The median longevity (L50) of the adult female at temperatureT(°C) is described by the equation 1/L50=e0.088(T−47.98)−1. The predicted lifelong total number of eggs (F) per female is given by the equationF= −196.11 + 42.65T− 1.1T2, and the lifelong total number of hosts killed (Hm) is given by the equationHm= 721.97 – 19.1T. The cumulative distributions of adult longevity, host mortality, and fecundity in relation to physiological age are described.

DOI:10.1093/ee/20.4.1195

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The effects of a maize,Zea maysL., genotype, ‘Zapalote Chico’ 2451#(P)(C3), resistant to the corn earworm,Helicoverpa zea(Boddie), alone and in combination with cytoplasmic polyhedrosis virus (CPV) on the growth and development of corn earworm were investigated. Corn earworm fed ‘Zapalote Chico’ silks incorporated into a laboratory diet were significantly smaller, had higher mortality, and required longer to complete each developmental stage when compared to those on control diet. CPV significantly reduced corn earworm larval and adult weights, prolonged larval developmental period, and adversely affected percentages of pupation and adult emergence. ‘Zapalote Chico’ and CPV interacted synergistically with respect to pupal and adult weights and antagonistically with respect to larval weight. Nevertheless, adults from treatment combinations of CPV and silk weighed up to 41% less than those of control diet. ‘Zapalote Chico’ and CPV were independent in action with respect to percent larval survival, percent pupation and percent adult emergence of corn earworm. The effects of silk and CPV on developmental times were most severe for the larval stage. Larval period was prolonged 5.3 d when larvae were fed ‘Zapalote Chico’ alone; but, in combination with CPV (which increased larval period by 1.6 d), duration of larval stage was synergistically prolonged 10.8 d (mean larval period, 23.8 d) when compared to that of the control diet. Pupal period in the treatment with combined silk and CPV was 13.2 d, which was significantly longer than the 11.8 d on control diet. The mean developmental period from neonate to adult for corn earworm fed silk was 30.3 d; but it synergistically increased to 37.4 d when CPV was given together with ‘Zapalote Chico’, as compared to 24.8 d in the control. The potential use of maize resistance and CPV in the integrated pest management of corn earworm is discussed.

DOI:10.1093/ee/20.4.1200

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The ubiquitous entomopathogenic fungusBeauveria bassiana(Balsamo) Vuillemin was applied to whorl-stage corn plants,Zea maysL., by foliar application of a granular formulation of conidia and by injection of a conidial suspension. Plants were analyzed at harvest for presence ofB. bassianaand for the amount of tunneling by laboratory-reared European corn borer larvae,Ostrinia nubilalis(Hübner). In 1989, 98.3% of the foliarly treated plants, 95.0% of the injected plants, and 33.3% of the nontreated plants were colonized byB. bassianaat harvest. In 1988, there were no significant differences between treatment effects onO. nubilalistunneling in plants. In 1989, when environmental conditions were more conducive to fungal growth, tunneling was significantly greater in the control plants, followed by the injected and foliarly treated plants. When applied to foliage,B. bassianaprovided the greatest amount ofO. nubilalissuppression. The entomopathogenic fungus colonized the corn plant at whorl stage, moved within the plant, and persisted to provide season-long suppression ofO. nubilalis.

DOI:10.1093/ee/20.4.1207

出版商:Oxford University Press    

年代:1991

数据来源: OUP

DOI:10.1093/ee/20.4.1212

出版商:Oxford University Press    

年代:1991

数据来源: OUP

DOI:10.1093/ee/20.4.1213

出版商:Oxford University Press    

年代:1991

数据来源: OUP