Search

Agrichemical usage on cereal crops grown in New Zealand was assessed from spray diaries for 45 barley fields and 81 wheat fields. From the 2008–09 growing season, 2.13 kg ai/ha (0.35 kg ai/t grain) and 2.93 kg ai/ha (0.31 kg ai/t grain) of agrichemicals of low-moderate human toxicity were applied to barley and wheat fields, respectively. For each crop, 0.31 and 0.33 kg ai/ha of fungicides, 0.14 and 0.28 kg ai/ha of insecticides, 1.46 and 1.47 kg ai/ha of herbicides and 0.22 and 0.85 kg ai/ha of plant growth regulators were applied. The data were reviewed with respect to pesticide resistance management guidelines. Although more than half of the agrichemical active ingredients (ai) applied, mostly herbicides, were classified by the Hazardous Substances and New Organisms (HSNO) Act 1996 as having high water or soil eco-toxicity, the amounts applied to the cereals on a per hectare basis were small (1.14 and 0.84 kg ai/ha, respectively) compared with that applied to comparable horticultural crops. Agrichemical use in cereal crops in New Zealand has remained generally static since 1998 despite incremental increases in yield, reflecting the arable sector's focus on protecting and building farm biodiversity, integrated pest management and agrichemical management. [ABSTRACT FROM PUBLISHER]

Abstract: Over two seasons (2002–03; 2003–04) at Pukekohe in the North Island and three seasons (2002–03; 2003–04; 2004–05) at Lincoln in the South Island of New Zealand, a common calendar-based insecticide regime was compared with a targeted insecticide regime for control of aphids on potatoes, and for any subsequent change in potato virus transmission by aphids. Treatments were an untreated control (1), calendar-applied fortnightly applications of methamidophos to foliage grown from untreated seed (2) and seed treated with imidacloprid (3), λ-cyhalothrin applied at an aphid threshold to foliage from untreated (4) or imidacloprid-treated seed (5) and pymetrozine at an aphid threshold to foliage from untreated seed (6). The action threshold for spraying was when apterous aphid populations exceeded 10 per 150 potato leaves. As indicated from suction traps at the trial sites, aphid flights peaked in autumn and spring. At Pukekohe in both years, aphids were not found on the potato foliage in any treatments until late January (midsummer), making 3–4 of the 5–7 methamidophos applications for the season unnecessary. Further applications of methamidophos kept apterous aphid populations at negligible levels until late summer, but populations in autumn tended to be higher than in untreated plots, due probably to the suppression of aphid predators (syrphids and lacewings) by the insecticide. No apterous aphids were found on potato foliage above the threshold in imidacloprid-treated or untreated plots until 3 weeks before desiccation of the foliage, necessitating only one application of λ-cyhalothrin or pymetrozine for each season. At Lincoln over all years, the imidacloprid seed treatment and the calendar-based 7–11 foliar applications of methamidophos kept plots free of aphids. However, the imidacloprid seed treatment alone, or one foliar application of λ-cyhalothrin alone or pymetrozine alone, were all that were required to keep aphid populations below the threshold during two of the three seasons, and were not required in the 2003–04 season. The incidence of tubers infected with potato leafroll virus (PLRV) and potato virus Y (PVY) at both sites was not significantly reduced by any insecticide treatment compared with the untreated control. The insecticide treatments also had no significant effect on total potato yields. In New Zealand, an imidacloprid seed treatment followed by a foliar application of λ-cyhalothrin or pymetrozine whenever apterous aphid populations exceed 10 per 150 potato leaves appears sufficient to maintain aphid populations below the action threshold, without compromising yields or increasing virus risk in tubers. [Copyright &y& Elsevier]

Tomatoes are an important source of antioxidant compounds, such as lycopene, phenolics and ascorbic acid. The main objective of this study was to determine the accessibility (availability for absorption) of the antioxidant compounds (total phenolics, total flavonoids, lycopene, ascorbic acid) and the antioxidant activity in fresh tomatoes of three cultivars (Excell, Tradiro and Flavourine) grown in New Zealand. The tomatoes were subjected to an in vitro digestion method, in which the pH, temperature, enzymes and chemical conditions were maintained according to human gastrointestinal conditions. The results showed that a high amount of the total phenolics and total flavonoids (71-77%) were released from tomatoes during digestion. However, only 3.2-4.5% of the total lycopene was released. No ascorbic acid could be detected after completion of in vitro digestion, probably due to degradation. After completion of digestion, the in vitro digestion extracts were found to have 45-50% antioxidant activity compared with the total antioxidant activity of fresh tomatoes (as measured by the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid diammonium salt radical decolourization assay). This study shows that the antioxidant components of tomatoes were affected by the in vitro digestion conditions depending on the type of compound. This in vitro digestion method gives an estimate of the release of antioxidant components in tomato, which may predict their in vivo behaviour. [ABSTRACT FROM AUTHOR]

Abstract: The prevalence of insecticide resistance mechanisms in populations of Myzus persicae on potatoes in New Zealand was determined in five parthenogenetic aphid lineages raised from individuals collected from Pukekohe in the North Island, and 66 from Canterbury and one from the West Coast in the South Island during mid-summer (January) to early autumn (March) 2005. For each lineage, the genotypes, determined using four microsatellite loci, were compared with the presence or absence of resistance mechanisms assessed using a combination of biochemical tests, polymerase chain reaction-based allelic discrimination and diagnostic dose bioassays. The 72 lineages comprised 23 genotypes (defined using microsatellite markers), with 60% containing one or more mechanisms that confer resistance to between one and three of any of four insecticide classes. In all, 38% contained high or extreme elevated carboxylesterases (E-Carb-R2 and -R3) that confer resistance primarily to organophosphates, and some resistance to carbamates and pyrethroids; 19% contained modified acetylcholinesterase (MACE) that gives strong resistance to the di-methyl carbamates, pirimicarb and triazamate; 54% contained a mutation in a voltage-gated sodium channel gene, called knockdown resistance (kdr), that confers resistance to pyrethroids; and 36% contained a second mutation of the gene (super-kdr) that gives enhanced resistance to pyrethroids. In all, 10% of the lineages also showed low-level resistance to neonicotinoids, as shown in imidacloprid diagnostic dose bioassays. Most of the microsatellite genotypes appeared to disclose cycles of sexual reproduction, the clones of which were susceptible to all classes of insecticide chemistry, except two that had acquired MACE possibly by breeding with an invasive MACE genotype or an individual carrying a locally derived MACE mutation. However, lineages carrying multiple resistance mechanisms belonged to two resistant genotypes that formed widely distributed clones. Behavioural bioassays on selected lineages from New Zealand and Europe showed that M. persicae clones from both regions carried E-Carb R3, or kdr/s-kdr, and showed consistently low responses to the aphid alarm pheromone (E)-β-farnesene. Methods are discussed for exploiting such putative fitness costs of resistance traits in M. persicae aphids to minimise the development of resistance and restore efficacy to insecticide programmes. [Copyright &y& Elsevier]

The objective of this study was to compare the antioxidant activities, total phenolics, lycopene and ascorbic acid content of four commercial tomato cultivars (Excell, Tradiro, Flavourine and Campari) of New Zealand, grown under similar hydroponic conditions. The mean antioxidant activity of the four cultivars, as measured with the ABTS radical decolourization assay, ranged from 2329 to 3268 µmole TEAC/100 g dry matter (DM) in the hydrophilic extracts and from 178 to 303 µmole TEAC/100 g DM in the lipophilic extracts. The major antioxidant components per 100 g DM were phenolics (343–451 mg gallic acid equivalents in hydrophilic extract and 53–74 mg gallic acid equivalents in lipophilic extract), flavonoids (175–204 mg rutin equivalents), ascorbic acid (153–195 mg) and lycopene (33–54 mg). Ascorbic acid and flavonoids were found to contribute 28–38% and 29–34%, respectively, to the antioxidant activity of the hydrophilic extract of tomatoes. The results showed that the smallest cultivar (Campari) had significantly ( P 0.05) higher antioxidant activities, total phenolics and flavonoids than the larger sized cultivars (Excell, Tradiro and Flavourine). This could be attributed to the significantly ( P 0.05) higher surface area/volume ratio of the small cultivar (0.15) when compared with the large-sized cultivars (0.10–0.12). The tomato cultivar (Flavourine) with a brighter red colour (higher a */ b * value), had a higher lycopene content as well, which suggests that the a */ b * value of tomatoes can be used as an indicator of their lycopene content. The phenolics ( r =0.84**) and flavonoids ( r =0.88**) were significantly related to the antioxidant activity of the hydrophilic extract, which suggests that measurement of total phenolics or flavonoids can be used as indicators of the antioxidant activity of tomatoes. [ABSTRACT FROM AUTHOR]