摘要:

Xylem-limited bacteria (XLB) were recovered from the sharpshooter leafhoppers,Homalodisca coagulata(Say),Oncometopia orbona(F.), andParaulacizes irrorata(F.), and cultured on artificial agar medium. Seasonal occurrence of XLB inH. coagulataand its plant hosts were determined by in vitro isolations and enzyme-linked immunosorbent assays (ELISA) for XLB. XLB were recovered frequently fromH. coagulatafrom numerous feeding hosts soon after they moved into peach orchards. Highest recoveries of XLB from host plants were from commercial plums,Prunus salicinaL. (70.1%), that showed visible leaf scald symptoms, followed by peaches,Prunus persica(L. [Batsch[) (31.4%).

ISSN:1754-5692    

DOI:10.1093/ee/16.1.68

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Amblyseius fallacis(Garman) diapause as inseminated adult females. Two aspects of diapause induction were investigated. First, I tested the effect of fluctuating temperatures on diapause induction, under conditions in which cryophase coincided with scotophase and daylength was 12 h, a photophase slightly longer than that previously reported as critical for diapause induction in this species. Second, I determined whether ovipositing female mites would diapause either when a 12:12 (L:D) photoperiod was continued, or when they were transferred from this cycle to photophases shorter than critical daylength. When reared with a 12:12 photoperiod, very few mites were in diapause on reaching the adult stage. Fluctuating thermoperiods of 25:20, 25:15, 25:10, 25:5, 20:15, 20:10, or 20:5 rarely induced diapause in any of the developing mites. Only one thermoperiod, a constant 15°C, served as a diapause-inducing stimulus in a significant number of mites. If mites were reared and maintained in a 12:12 photoperiod at 15°C throughout their lives, all females entered diapause after an oviposition period lasting ≤33 d, then resumed oviposition 34–88 d later. Transferring adult females from 12:12 to either 11:13 or 8:16 photoperiods after 10, 14, 17, or 21 d as adults also induced diapause, usually in a shorter period of time than was required for mites continuously exposed to a 12-h photophase.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.72

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Temperatures of wheat in the top meter in on-farm cylindrical metal bins in Kansas were uniform and within a favorable range of 27–34°C for the first 12 wk and then declined at rates ranging from 1.3 to 2°C/wk. Cooling of grain from the outside and surface inward and downward resulted in temperature gradients. Grain moisture in the top 0.5 m declined during the first 12 wk and then increased to levels well above initial moisture. Elsewhere in the top meter, wheat retained its initial moisture level except for the tendency of grain near the bin wall to be drier. Population growth rate of the dominant species,Cryptolestes ferrugineus(Stephens), declined over the wheat storage period in the top meter of grain as a result of first the parasiteCephalonomia waterstoniGahan and then falling temperatures.C. ferrugineusadults showed only a slight tendency to move toward the warmer or moister parts of the bin.Trogoderma glahrum(Herbst) adults and larvae andTrogoderma inclusumLeConte adults, the next most abundant species, were found mainly near the bin wall.Rhyzopertha dominica(F.) were first detected after 12 wk and were found only in the center.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.77

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A rapid technique using sex pheromone and insecticide-laced traps was developed for measuring insecticide resistance in pink bollworm moth,Pectinophora gossypiella(Saunders). This method was developed in the laboratory by allowing males to fly upwind to a sex-pheromone source in a wind tunnel, and then trapping them on sticky cards (laced with various doses of pyrethroid insecticides) inserted into standard delta traps. Using this technique, populations of adult maleP. gossypiellatrapped in the field were shown to be more resistant to permethrin and fenvalerate in fields frequently treated with pyrethroids than in fields with little or no exposure to these insecticides. The new method eliminates handling of insects that is involved in other methods of assessing toxicity, and is compatible with the current practice of monitoring populations with pheromone traps. It was important to test and standardize duration of males' postcapture exposure to insecticide-laced sticker, temperature that males were exposed to after capture, quantity of sticker used, and age of males when captured.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.84

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A stocking technique was used during 1977–81 to assess predation on egg masses of the Douglas-fir tussock moth,Orgyia pseudotsugata(McDunnough), in Oregon, Idaho, and California. Predators removed ca. 14% of stocked egg masses. The remainder of the egg masses not completely destroyed lost ca. 38% of their original complement of eggs. Three species of birds, the red-breasted nuthatch,Sitta canadensisL.; the dark-eyed junco,Junco hyemalisL.; and the Nashville warbler,Vermivora ruficapilla(Wilson); and a treeforaging ant,Camponotussp. probablymodocWheeler, are implicated as primary predators.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.90

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Direct observation and radiolabeling techniques were used to investigate movement and burrowing activity of prepupalHeliothis zea(Boddie) released in the field. Microenvironmental conditions as a function of tillage method influenced prepupa behavior differently in successive years. In a moist year, prepupae tended to burrow closer to the release site in no-tillage plots than in conventionally tilled plots; in a dry year, this trend was reversed. Distance that prepupae moved on the soil surface and time they required for burrowing were influenced by both soil type and moisture conditions. Overall, prepupae traveled greater distances and spent more time on the soil surface when the soil was smooth or crusted. Ant attacks were more frequent on prepupae in no-tillage treatments than in conventional tillage. A field cage study revealed no differences in survivorship between insects released in the two tillage treatments.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.94

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Replicated plots (112.2 m2) of Kentucky bluegrass turf were maintained for 4 yr on a schedule of fertilizer, herbicide, and insecticide treatments, or were unmanaged except for mowing. Impact of the high-maintenance program on predators, decomposers, and nontarget herbivorous insects was determined from pitfall-trap collections, soil and thatch extractions, and sweep-net and formalin-drench samples. Trap catches of predaceous arthropods, specifically Araneae, Staphylinidae, and Carabidae, were significantly reduced by insecticides, particularly late-summer soil treatment with diazinon. Predators repopulated treated plots by the following spring. Chrysomelidae were more abundant on high-maintenance plots in spring. Soil and thatch pH decreased significantly and thatch accumulation more than tripled under the high-maintenance program. However, earthworms were relatively unaffected, and oribatid mites were generally more abundant in high-maintenance plots. This suggests that thatch accumulation was probably more a consequence of increased vegetative production than of decreased decomposition due to depletion of soil invertebrates. Although high-maintenance lawn-care programs affect many groups of nontarget invertebrates, this study suggests that the effects are variable and in some cases less severe than would be expected, given the quantity and frequency of pesticide and fertilizer use.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.100

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Plant age of a moderately resistant rice cultivar, ‘IR36’, had a distinct effect on the level ofNephotettix virescens(Distant) resistance. Plants at 10 d after sowing (DAS) were preferred over those at 20, 40, or 60 DAS.N. virescenssurvival, growth index, and adult weight were higher on plants 20 DAS than on plants 40, 60, or 80 DAS. Although the total amount of honeydew excreted was similar for ‘IR36’ plants of all ages, the reaction of honeydew on filter paper treated with bromocresol green indicated that feeding in the nutrient-rich phloem was highest on the younger plants. Tungro virus transmission was related to extent of phloem feeding and the percentage of infection was highest on young plants.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.106

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The flowerhead weevilRhinocyllus conicus(Froelich) was introduced from Europe into California in the early 1970's for biological control of weedy thistlesCarduus nutansL.,Carduus pycnocephalusL., andSilybum marianum(L.) Gaertn. (Cardueae). In this study, adultR. conicuswas reared from flowerheads collected from natural populations of 12 species of native, nontargetCirsiumthistles in California:Cirsium andersonii(Gray) Petrak,C. brevistylumCronq.,C. californicumGray,C. campylonH. Sharsm.,C. callilepis(Greene) Jeps.,C. ciliolatum(L. Henders.) J. T. Howell,C. cymosum(Greene) J. T. Howell,C. douglasiiDC.,C. hydrophilum(Greene) Jeps. var.vaseyi(Gray) J. T. Howell,C. pastorisJ. T. Howell,C. proteanumJ. T. Howell, andC. tioganumCongd. These are new host records for this weevil. This extension of its host range is not surprising because EuropeanCirsiumwas known to be within the host range ofR. conicus. The impact, if any, of these new host associations is not yet known. The weevil was also reared from the naturalized weedy thistlesC. nutans,C. pycnocephalus,C. tenuiflorusW. Curt.,Cirsium arvense(L.) Scop.,Cirsium vulgare(Savi) Tenore, andS. marianum. Quantitative rearing data are reported for each thistle host.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.111

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Development, longevity, and reproduction of fall armyworms,Spodoptera frugiperda(J. E. Smith), from Louisiana (LA) and Puerto Rico (PR) were studied on an artificial diet and on rice foliage. PR larvae developed more slowly than LA larvae and produced lighter adult females. This difference did not extend to adult longevity or reproductive parameters, but the next generation of first instars was smaller. Developmental parameters were not influenced by diet. The results suggest the possibility of a genetic difference between the two populations, indicating some degree of reproductive isolation.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.116

出版商:Oxford University Press    

年代:1987

数据来源: OUP