摘要:

Studies were conducted to examine the physiological response of peppermint,Mentha piperitaL., to leaf water stress induced by feeding of the twospotted spider mite,Tetranychus urticaeKoch (Acari: Tetranychidae). Levels of mite injury were estimated by a leaf injury index developed for these studies. Symptoms of water stress in mite-injured leaves were: a significant reduction in leaf fresh weight; reduced leaf specific weight (mg of fresh weight per cm2of leaf area); and accumulation of soluble leaf carbohydrates. Soluble leaf carbohydrates of peppermint are sucrose (ca. 50%) and the galactosyl oligosaccharides raffinose and stachyose. Leaf starch content was unaffected by injury at all injury levels. Accumulation of soluble leaf carbohydrate in water-stressed leaves may help mite-injured leaves maintain cell turgor pressure through an osmotic adjustment (osmoregulation) mechanism. A new method for in situ starch hydrolysis for quantitative analysis of leaf starch also is presented.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.336

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Field studies were conducted in 1979 and 1980 to determine whether differences exist in feeding behavior between black cutworm,Agrotis ipsilon(Hufnagel), larvae reared 1, 12, and 24 generations. Larvae were released on corn at three developmental stages (coleoptile, two leaf, and four leaf). Damage was more severe during the coleoptile stage. Also, corn seedlings in the two-leaf stage had significantly more damage than corn in the four-leaf stage of development. Irrespective of corn developmental stage, however, more damage occurred on corn after weed seedling removal than on corn adjacent to weed seedlings. The feeding behavior of larval populations of black cutworm reared for one or multi-generations in the laboratory was not significantly different

ISSN:0046-225X    

DOI:10.1093/ee/12.2.340

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Effects of feeding injury by the twospotted spider mite,Tetranychus urticaeKoch (Acari: Tetranychidae), on 14-CO2assimilation (net photosynthesis), leaf conductance to gas exchange, and leaf chlorophyll in peppermint,Mentha piperitaL., were investigated. Rates of 14-CO2, assimilation were reduced in proportion to degree of sustained injury and probably were the result of reduced leaf conductance to gas exchange, which inhibited influx of carbon dioxide to chloroplasts. Assimilation rates for both uninjured and variously injured leaves were correlated with leaf conductance. Inhibition of gas exchange in injured leaves was the predominant factor responsible for reduced photosynthesis. Extractable leaf chlorophyll was reduced in proportion to the degree of injury sustained. Leaf injury was estimated by using an injury index developed for these studies

ISSN:0046-225X    

DOI:10.1093/ee/12.2.345

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

This study further confirms that nectariless cultivars of cotton are less attractive than the near-isogenic nectaried cultivars when grown in small plots. The results also indicate that pest and beneficial arthropods are not reduced to the same degree. Of the 15 pest categories, 7 were little reduced by the nectariless cultivar, whereas the remaining eight had reductions of 24 to 42% averaged for the 4-year study period. All 15 beneficial species categories showed a significant (P<0.05) reduction on the nectariless cultivar (38 to 69% four year averaged reduction), these being affected to a greater degree than the pest. A disturbing question that remains is whether the utility of nectariless cultivars for reducing pest pressures is afforded at commercial levels of planting. As plot size increased from 0.11 to 4.05 ha, the reduction on the nectariless cultivar decreased from ca. 38 to 32%. The rate at which the differences between the nectaried and nectariless cultivars decreases implies that the advantage with the nectariless cultivar might disappear with commercial scale plantings. Further large-scale trials would however be required for confirmation of this trend

ISSN:0046-225X    

DOI:10.1093/ee/12.2.349

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The nectariless, near-isogenic cultivar of ‘Stoneville 7A' produced a higher yield than its nectaried counterpart due to: (1) an intrinsically greater yield potential, and (2) a reduced attractiveness to insect pests which resulted in a reduction in pest damage. The greatest yield advantage occurred with the unsprayed field comparison where the nectariless cultivar had ca. 40% less damaged fruit over each of the 4 years. The nectariless cultivar also matured earlier, as much as 18 days with the unsprayed field comparison. The reduction in pest damage and earlier maturity for the nectariless cultivar has considerable significance for cotton crop production

ISSN:0046-225X    

DOI:10.1093/ee/12.2.353

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Development, oviposition, and mortality rates for Banks grass mite,Oligonychus pratensis(Banks) feeding on blue grama grass,Bouteloua gracitis(H.B.K.) Griffiths, were measured at constant temperatures of 19, 25, and 31°C. Complete life tables were computed from these data for each of the three temperatures. Developmental, survival, and ovipositional curves are given in both tabular and graphical form. It is apparent that the optimum temperature forO. pratensisis greater than 31°C. Population growth rate forO. pratensisfeeding on blue grama was similar to that previously reported for populations feeding on sorghum and barley.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.359

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The mean consumption rate after 72 h in the laboratory ofIps grandicollis(Eichhoff) eggs byLyctocoris elongatus(Reuter) was significantly higher (P<0.05) for all feeding life stages than that byScoloposcelis mississippensisDrake and Harris. Both anthocorid species fed on bark beetle eggs, larvae, and pupae and showed evidence of cannibalism and territoriality. AdultS. mississippensisalso fed on several associated insect predators and parasites of bark beetles. Fifth-instar nymphs ofS. mississippensisdid not differ significantly (P<0.05) in consumption rates forI. grandicollisandDendroctonus frontalisZimmermann eggs

ISSN:0046-225X    

DOI:10.1093/ee/12.2.363

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Guinea pigs, mice, and rats were exposed toXenorhabdus nematophilus, the entomopathogenic bacterial symbiont ofNeoaplectana bibionis, by oral, intradermal, subcutaneous, and intraperitoneal routes, and by inhalation and skin contact. Rabbits were exposed by conjunctival inoculation. There was no evidence of infectivity, pathogenicity, or toxicity in any of the test animals.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.368

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The effects of pheromone trap design and trap placement on collections of male San Jose scale,Quadraspidiotus perniciosus(Comstock), were studied over a 3-year period in California, Oregon, and Washington. Open (tent) trap designs were more efficient than closed traps, with small tent traps as good as larger tent traps. Trap placement in the north or east tree quadrants consistently produced the highest collections of male scale, but these catches are probably influenced by local meteorological conditions at the time of male flight. Collections of male scale increased as trap height increased into the upper tree canopy. Comparisons of the three pheromone isomers showed isomer SJS-3 generally to be more attractive than either SJS-1 or SJS-2. Pheromone dispenser load rates of 100 to 1,000 μg of SJS-2 showed no significant reduction in scale collections with 300- to 1,000-μg rates, compared with fresh 300-μg loads after 8 weeks of field exposure. Fresh, 300-μg loads were significantly better than all dispensers aged 16 to 19 weeks in the field

ISSN:0046-225X    

DOI:10.1093/ee/12.2.371

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

A method for screening seedling and older rice plants for resistance toMythimna separata(Walker) andSpodoptera mauritia acronyctoides(Guenee) was developed. In all seedling stage tests, many entries were readily fed upon, and when the most susceptible entries were consumed, the nonpreferred varieties were also heavily damaged. The most resistant varieties in the seedling stage were those belonging to the wild rice groups, especially group II, which has a different genomic constitution thanOryza sativa.In tests involving older plants, IR20, IR46, and B-441-B-126-1-2-3 were heavily damaged when infested with 2nd- and 3rd-instar larvae

ISSN:0046-225X    

DOI:10.1093/ee/12.2.376

出版商:Oxford University Press    

年代:1983

数据来源: OUP