Mortality,progeny production and preference of Sitophilus zeamais adults to wheat from integrated and alternative production systems

The objectives of this study were to assess the effects of the production systems of wheat from different production systems on the mortality, progeny production and preference of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). The factors tested were production system (integrated [INT], organic [ORG], biodynamic [BD] and control), which differed in plant protection and fertiliser procedures during plant growth and development; exposure interval (7, 14 and 21 d); relative humidity (r.h.) (55% and 75%) and temperature (20°C, 25°C and 30°C). Mortality after 7 d increased with the temperature increase and decreased with the increase in r.h. in most of the tested combinations. The mortality of weevils was higher in ORG compared to INT-produced wheat after 7 d. Progeny production was recorded 56 d after removal of parental adults and was higher at 75% r.h. in comparison to 55% r.h. At 55% r.h. and 20°C, progeny was 60.8% higher when S. zeamais were exposed to ORG in comparison to INT-produced wheat. Wheat from different production systems influenced mortality rates which were higher in alternative compared to INT production systems under optimal conditions for wheat storage (low temperature and r.h.). The reverse was recorded for temperature and r.h. increase. Progeny was not affected by wheat from various production systems. Significantly more S. zeamais adults were found in traps containing wheat from BD and control in comparison to INT. An understanding of the agricultural processes, biotic and abiotic factors which alter the post-harvest response of storage pests could be useful for the development of efficient post-harvest strategies for ORG and BD farms and the processing industry.     

Enzyme-linked immunosorbent assay with single or combined antisera for viruses S and X in potato tubers and plants

Enzyme-linked immunosorbent assay (ELISA), with single or combined antisera was effective for diagnosing potato virus S (PVS), potato virus X (PVX) or both viruses in plants grown in the greenhouse or field. In dormant tubers, stolon, middle and apical end composite sampling with or without eyes and sprouted tubers produced reliable positive assays for PVX. Only tuber pieces with sprouts resulted in consistently reliable assays for PVS. Composite sampling of potato foliage was effective for detecting one PVX infected plant in a total of 100 Kennebec, Norland, or Russet Burbank plants. There were some false negative results and greater variability in composite PVS assays, but on average, one PVS infected plant can be detected in composites of 10 Kennebec, Norland, or Russet Burbank plants. Sodium diethyldithiocarbamate (0.01M NaDIECA) in phosphate buffered saline + 0.5% Tween (PBS-T) added to plant extracts enhanced specific reactions for either virus. Onceor twiceused enzyme conjugate was effective in ELISA of either virus from potato foliage.     

Evaluation of sprinkler application of fungicides for control of potato early blight in Colorado

Sprinkler application of four fungicides, Du-Ter 47.5% W.P. (0.70 kg/ha), Difolatan 4F (3.51 1/ha), Bravo W-75 (1.68 kg/ha) and Bravo 500 (1.17 1/ha, 1.761/ha and 2.341/ha) were evaluated in Colorado for control of potato early blight caused byAlternaria solani (Ellis & G. Martin) L.R. Jones and Grout and compared to the conventional method of airplane application. Fungicides applied through center pivot irrigation systems generally achieved disease control equal to airplane application. Application of fungicides through both center pivot sprinklers and by airplane effectively reduced early blight infection. Control of early blight by airplane or sprinkler application of fungicides significantly (P = 0.05) increased potato yields in 1978. In other years (1977, 1979 and 1980) fungicide applications which reduced disease severity generally increased tuber yields but the increases were not significant when compared to the control.     

Translocation and mechanical spread of a Minnesota isolate of potato virus S in potatoes

Potato cultivars Norland, Kennebec, and Russet Burbank were inoculated with a Minnesota isolate of potato virus S (PVS) in the field. The incidence of secondary infection, measured by enzyme-linked immunosorbent assay (ELISA), indicated that significantly more PVS infection occurred in Russet Burbank than Norland or Kennebec, and that Norland had significantly more infection than Kennebec (P≤ 0.01). Mature plant resistance was not observed. Rapid reinfection of PVS-free seedlots resulted from inoculum point-sources when routine cultivation practices were followed. Reinfection rates were significantly greater for seedlots grown at Grand Forks, ND, when compared with seedlots grown at Becker, MN, during both years of the study (P≤ 0.01). After two years in the field, reinfection rates for Norland (71.8%) and Russet Burbank (73.0%) did not differ significantly, but were significantly greater than the reinfection rate for Kennebec (29.5%) (P≤ 0.01). In greenhouse-grown plants, PVS moved out of rub-inoculated leaves within 24 hr, however, 13 and 20 days were required before PVS was detected with ELISA in foliage above and below the inoculated leaf, respectively. The frequency of PVS detection was significantly greater in foliage above the inoculated leaf compared to foliage below the inoculated leaf (P≤ 0.05). Translocation of PVS from inoculated leaves to daughter tubers occurred within 13 days for Russet Burbank and Norland and within 20 days for Kennebec.     

Frequent recombination in a saltern population of Halorubrum

Sex and recombination are driving forces in the evolution of eukaryotes. Homologous recombination is known to be the dominant process in the divergence of many bacterial species. For Archaea, the only direct evidence bearing on the importance or natural occurrence of homologous recombination is anecdotal reports of mosaicism from comparative genomic studies. Genetic studies, however, reveal that recombination may play a significant role in generating diversity among members of at least one archaeal group, the haloarchaea. We used multi-locus sequence typing to demonstrate that haloarchaea exchange genetic information promiscuously, exhibiting a degree of linkage equilibrium approaching that of a sexual population.     

Antigenotoxicity and Antioxidant Activity of Acerola Fruit (Malpighia glabra L.) at Two Stages of Ripeness

Genotoxic and antigenotoxic effects of acerola fruit at two stages of ripeness were investigated using mice blood cells. The results show that no ripeness stage of acerola extracts presented any genotoxic potential to damage DNA (Comet assay) or cytotoxicity (MTT assay). When antigenotoxic activity was analyzed, unripe fruit presented higher DNA protection than ripe fruit (red color) extract. The antioxidant capacity of substances also showed that unripe samples inhibit the free radical DPPH more significantly than the ripe ones. The results about determination of compounds made using HPLC showed that unripe acerola presents higher levels of vitamin C as compared to ripe acerola. Thus, vitamin C and the complex mixture of nutrients of Malpighia glabra L., and especially its ripeness stages, influenced the interaction of the fruit extract with the DNA. Acerola is usually consumed when ripe (red fruit), although it is the green fruit (unripe) that has higher potential as beneficial to DNA, protecting it against oxidative stress.     

Comparison of the activity of selamectin, imidacloprid and fipronil for the treatment of dogs infested experimentally with Ctenocephalides canis and Ctenocephalides felis felis.

Twenty-four beagles were randomly allocated into four groups of six and housed in separate cages. Each dog was infested with 25 Ctenocephalides canis and 25 Ctenocephalides felis felis and two days later (day 0) the dogs in groups 1, 2 and 3 received a spot-on application of selamectin (6 mg/kg), imidacloprid (10 mg/kg), or fipronil (6-7 mg/kg), respectively, while the dogs in group 4 were not treated. The dogs were combed 48 hours later, the fleas were removed, counted and their species were determined. All the dogs were reinfested with the same number of the two species of fleas on days 7, 14, 21, 28 and 35, and the efficacy of the treatments was calculated 48 hours after each infestation. The mean numbers of fleas on the control dogs were 19.8 C. canis and 14.7 C. felis felis. The three treatments were effective for the full 35 days of the trial; over the first 28 days, the efficacy of selamectin ranged from 81 to 100 and 92 to 99 per cent against C. felis felis and C canis, respectively, the efficacy of imidacloprid ranged from 98 to 100 per cent and the efficacy of fipronil was 100 per cent against both species. There were no significant differences between the three treatments.