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111.
Antonio López-Carretero Magdalena Cruz & Astrid Eben 《Entomologia Experimentalis et Applicata》2005,115(1):27-31
The effect of a non‐host plant, Solanum myriacanthum, on ovarian dynamics and longevity of Leptinotarsa undecimlineata (Stål) (Coleoptera: Chrysomelidae) was studied under laboratory conditions. Females reared on the natural host, S. lanceolatum, served as controls. Female beetles did not accumulate eggs on the non‐host. After continuous exposure to S. myriacanthum, the production of basal oocytes was diminished and oocytes were reabsorbed. Oocyte size, however, was not affected when compared to females fed with S. lanceolatum. In control females, the first mature eggs appeared at 34 days old. No eggs matured in females fed with the non‐host in the 54‐day duration of our experiment. Continuous exposure to the non‐host resulted in significantly less resorption of reproductive resources than a stress period of 20 days on the non‐host. Egg resorption was completely reversible after the preferred host was re‐offered for another 20 days. Further studies under field conditions will be necessary to understand why this Leptinotarsa species uses only one of two sympatric Solanum species. 相似文献
112.
Birds free from nest predators for long periods may either lose the ability to recognize and respond to predators or retain antipredator responses if they are not too costly. How these alternate scenarios play out has rarely been investigated in an avian community whose members have different evolutionary histories. We presented models of two nest predators (rat and snake) and a negative control (tree branch) to birds on Hawai?i Island. Endemic Hawaiian birds evolved in the absence of terrestrial predators until rats were introduced approximately 1,000 years ago. Introduced birds evolved with diverse predator communities including mammals and snakes, but since their introduction onto the island approximately one century ago have been free from snake predation. We found that (a) endemic and introduced birds had higher agitation scores toward the rat model compared with the branch, and (b) none of the endemic birds reacted to the snake model, while one introduced bird, the Red‐billed Leiothrix (Leiothrix lutea), reacted as strongly to the snake as to the rat. Overall, endemic and introduced birds differ in their response to predators, but some endemic birds have the capacity to recognize and respond to introduced rats, and one introduced bird species retained recognition of snake predators from which they had been free for nearly a century, while another apparently lost that ability. Our results indicate that the retention or loss of predator recognition by introduced and endemic island birds is variable, shaped by each species' unique history, ecology, and the potential interplay of genetic drift, and that endemic Hawaiian birds could be especially vulnerable to introduced snake predators. 相似文献
113.
Travis Longcore Christine S. Lam Patrick Kobernus Eben Polk John P. Wilson 《Journal of Insect Conservation》2010,14(4):335-346
Managers surveyed for sensitive butterfly species in the San Bruno Mountain Habitat Conservation Plan area between 1982 and
2000 using an opportunistic “wandering transect” method. To extract as much valuable information as possible from the data
collected by this method we analyzed patterns of surveys and butterfly presence and absence within 250 m square cells gridded
across the area within a Geographic Information System. While estimates of butterfly abundance were not possible, the data
could be tested for trends in butterfly occupancy. For those cells surveyed during at least 10 years, no trends in the total
number of occupied cells was evident for either Callippe silverspot or mission blue butterfly. There were cells, however,
that showed positive or negative trends (P < 0.20) in occupancy for each species (Callippe silverspot: 14 positive, 15 negative, 6 cells occupied all years; mission
blue butterfly: 40 positive, 40 negative, 2 cells occupied all years). We conclude that for the period 1982–2000 the population
of each species was stable in overall total distribution, but indicate geographic areas of concern for each, specifically
the edges of the northeast ridge for Callippe silverspot butterfly and the northwest of the study area for mission blue butterfly.
Vegetation composition analysis using orthophotography with field corroboration indicates that those areas with declines in
occupancy for these species experienced native coastal scrub succession and a corresponding loss in grassland butterfly habitat,
while positive trending and stable cells had stable grassland proportions. Habitat managers at San Bruno Mountain should therefore
incorporate programs for protecting grassland butterfly habitat not only from invasive weeds but also from succession to native
coastal scrub. This approach illustrates the feasibility of using occupancy as an indicator to track butterfly status in a
protected area even when suboptimal data collection methods are used, but the difficulties of using these data also reinforces
the need for managers to devise monitoring schemes appropriate for their objectives before implementing them. 相似文献
114.
A new tremorgenic metabolite from Penicillium paxilli 总被引:1,自引:0,他引:1
115.
A diarrheagenic toxin from culture extracts of Aspergillus wentii Wehmer isolated from weevil-damaged Chinese chestnuts was identified as emodin (2-methyl-4,5,7-trihydroxyanthraquinone). The orange-red, crystalline toxin (mp 255 to 257 C) showed ultraviolet absorption maxima in ethyl alcohol at 223, 250, 267, 290, and 442 nm, and infrared absorption maxima at 3,400 cm-1 (OH), 1,635, and 1,625 CM-1. Chemical shifts and coupling constants of the proton magnetic resonance spectra of the A. wentii toxin and of authentic emodin agreed. Mean lethal dose of emodin orally administered to 1-day-old DeKalb cockerels was 3.7 mg/kg. 相似文献
116.
A practical method of screening fungi for toxin-producing potential uses day-old cockerels dosed via crop intubation with chloroform extracts of mold cultures and extracted culture residues mixed with ration fedad libitum. Advantages of the method are worker safety, simplicity, and economy. The method detected mycotoxin-producing fungi from several genera commonly found contaminating peanuts. 相似文献
117.
R J Cole J W Kirksey H G Cutler D M Wilson G Morgan-Jones 《Canadian journal of microbiology》1976,22(5):741-744
Two new isomeric metabolites, toxins A and B, were isolated from culture extracts of Penicillium islandicum. Both toxins had a molecular formula of C16H15O2N2Cl, and physical and chemical analyses indicated that they were indole alkaloids. LD50 of toxin A was about 75-125 mg/kg in day-old cockerels. Insufficient toxin B was available to determine accurate LD50 values. Toxin A moderately inhibited growth of wheat coleoptiles but did not inhibit growth of week-old intact corn and bean plants. Toxin B showed no plant-growth inhibition. 相似文献