摘要:

The cumulative effects of low prey densities on predation and ovipositon ofZetzellia mali(Ewing) were tested. Prey were eggs ofPanonychus ulmi(Koch) andTetranychus urticaeKoch. Predators exposed to low prey densities disproportionately reduced their predation and oviposition rates as compared with high densities. The effects were cumulative; the longer the predators were exposed to low prey densities the lower were their rates of predation and oviposition. These decreases were not permanent.Z. maliincreased both responses when prey were available.Z. maliwas also cannibalistic and survived without prey for 23.6 days. These phenomena may explain whyZ. malisurvives on apple leaves when few prey are present.

ISSN:0046-225X    

DOI:10.1093/ee/11.4.972

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Studies were conducted to examine effects of feeding injury by the spider mite,Tetranychus urticaeKoch (Acari: Tetranychidae), on diurnal transpiration and daytime leaf water status in peppermint,Mentha piperitaL. A new approach to investigate mite injury of the leaf epidermis and cuticle is presented. Feeding injury significantly affected daytime stomatal transpiration and nighttime cuticular transpiration. High rates of nighttime transpiration that resulted from mite injury to leaf epidermal cells and overlying cuticle caused leaf water stress during the day. Differences in rates of transpiration during the day and night, between uninjured and injured leaves. were correlated with a leaf injury index developed for this study. Water stress (more negative leaf osmotic potential) developed in injured leaves during the day and the magnitude of stress was correlated with our leaf injury index. Continued water loss at night from mite-injured leaves is discussed in terms of the underlying cause of water stress during the day.

ISSN:0046-225X    

DOI:10.1093/ee/11.4.975

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Host acceptance and development ofHeliothis subflexa(Guenee),H. virescens(F.), their hybrid, and backcross (BC) progeny on several plant species were studied. Backcrossing hybrids toH. virescensresulted in progeny behaviorally similar to their recurrent parent. The BC progeny were able to utilize host plants that were acceptable toH. virescens. AlthoughH. subflexaexhibited growth and development on some atypical host plants under forced conditions, none have been verified as specific hosts in the field.

ISSN:0046-225X    

DOI:10.1093/ee/11.4.979

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Aspects of the reproductive biology of the larviparous tachinid parasitoidBonnetia comtawere evaluated under laboratory conditions. Adult survivorship and age-specific fecundity curves were developed. Mean fecundity was 413 planidia per female; a small positive correlation was found between female size and fecundity. Thermoperiodic conditions and behavioral responses to photophase were shown to determine diel reproductive cycles. The intensity of larviposition by the fly was found to be governed by the quantity and quality (species) of larvipositional stimulant (host fecal pellets) present. The results demonstrate how a diurnally active parasitoid may obtain access to a nocturnally active, diurnally concealed host, and how certain physical and biological factors are involved in the allocation of reproductive resources in time and space.

ISSN:0046-225X    

DOI:10.1093/ee/11.4.981

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

A sex pheromone component for the webbing coneworm,Dioryctria disclusa, has been identified as (Z)-9-tetradecenyl acetate. Traps baited with rubber septa impregnated with this compound at loadings of 30 to 300 μg caught the same as or significantly better than traps baited with two virgin female moths. Addition of 3 to 30% of theE isomerdid not increase trap catch, and only (Z)-9-tetradecenyl acetate was found in the female extract.

ISSN:0046-225X    

DOI:10.1093/ee/11.4.986

出版商:Oxford University Press    

年代:1982

数据来源: OUP