Archaeological science meets Maori knowledge to model pre-Columbian sweet potato (Ipomoea batatas) dispersal to Polynesia's southernmost habitable margins.

Most scholars of the subject consider that a pre-Columbian transpacific transfer accounts for the historical role of American sweet potato Ipomoea batatas as the kumara staple of Indigenous New Zealand/Aotearoa Maori in cooler southwestern Polynesia. Archaeologists have recorded evidence of ancient Polynesian I. batatas cultivation from warmer parts of generally temperate-climate Aotearoa, while assuming that the archipelago's traditional Murihiku region in southern South Island/Te Waipounamu was too cold to grow and store live Polynesian crops, including relatively hardy kumara. However, archaeological pits in the form of seasonal Maori kumara stores (rua kumara) have been discovered unexpectedly at Purakaunui on eastern Murihuku's Otago coast, over 200 km south of the current Polynesian limit of record for premodern I. batatas production. Secure pit deposits that incorporate starch granules with I. batatas characteristics are radiocarbon-dated within the decadal range 1430-1460 CE at 95% probability in a Bayesian age model, about 150 years after Polynesians first settled Te Waipounamu. These archaeological data become relevant to a body of Maori oral history accounts and traditional knowledge (matauranga) concerning southern kumara, incorporating names, memories, landscape features and seemingly enigmatic references to an ancient Murihiku crop presence. Selected components of this lore are interpreted through comparative exegesis for correlation with archaeological science results in testable models of change. In a transfer and adaptation model, crop stores if not seasonal production technologies also were introduced from a warmer, agricultural Aotearoa region into dune microclimates of 15th-century coastal Otago to mitigate megafaunal loss, and perhaps to support Polynesia's southernmost residential chiefdom in its earliest phase. A crop loss model proposes that cooler seasonal temperatures of the post-1450 Little Ice Age and (or) political change constrained kumara supply and storage options in Murihiku. The loss model allows for the disappearance of kumara largely, but not entirely, as a traditional Otago crop presence in Maori social memory.

Comparative aquatic toxicity of the pyrethroid insecticide lambda-cyhalothrin and its resolved isomer gamma-cyhalothrin.

In this review we compare the sensitivity of a range of aquatic invertebrate and fish species to gamma-cyhalothrin (GCH), the insecticidally active enantiomer of the synthetic pyrethroid lambda-cyhalothrin (LCH), in single-species laboratory tests and outdoor multi-species ecosystem tests. Species sensitivity distribution curves for GCH gave median HC(5) values of 0.47 ng/L for invertebrates, and 23.7 ng/L for fish, while curves for LCH gave median HC(5) values of 1.05 ng/L and 40.9 ng/L for invertebrates and fish, respectively. A model ecosystem test with GCH gave a community-level no observed effect concentration (NOEC(community)) of 5 ng/L, while model ecosystem tests with LCH gave a NOEC(community) of 10 ng/L. These comparisons between GCH and LCH indicate that the single active enantiomer causes effects at approximately one-half the concentration at which the racemate causes similar effects.

Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests.

The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC(50): 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC(50) acute toxicity data for eight species, gave a median HC(5) value for GCH of 2.12 ng/l. The NOEC(community) derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC(5), based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOEC(community) for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC(5) and NOEC(community)) were consistent with expectations when compared to the equivalent endpoints for the racemate LCH.

The soil ecotoxicology of 1,3-dichloropropene under commercial growing conditions.

Soil fumigants are used extensively in the protection of crops against parasitic nematodes and other soil borne pests. The active ingredient in Telone II soil fumigant is 1,3-Dichloropropene (1,3-D) which has a wide range of uses in Europe as a pre-plant nematocide. During the use of soil fumigants such as 1,3-D a range of non-target soil dwelling organisms has the potential to be exposed and impacted. We report here the results of a field study conducted in Italy to assess the impact of 1,3-D applications to soil-dwelling non-target organisms. This study was conducted under conditions of commercial tomato growing either without (untreated control) or with an application of 1,3-D at 224 kg a.i./hectare. Samples of arthropods and earthworms were taken before and up to 12 months after application to measure season long effects. A soil sample was taken at 4.5 months and a soil function test performed. By evaluating the effects of 1,3-D both in the Laboratory and under field conditions equivalent to commercial practices it was concluded that applications of 1,3-D would not adversely effect soil arthropods, but may have an effect on earthworms and soil microflora. These effects were, however, transient as full recovery was observed within six months of application for earthworms and 4.5 months for soil microflora. Consequently, the risk to non-target soil micro- and macro-organisms was considered acceptable according to current risk assessment guidelines within the European Union.

Exposure of small mammals, in particular the wood mouse Apodemus sylvaticus, to pesticide seed treatments.

Field exposure of small mammals to fungicide-treated wheat seed was investigated over three weeks following drilling on fields near York, United Kingdom. Seed consumption by small mammals trapped on and immediately adjacent to the drilled fields was quantified by measuring the amount of seed in the stomach. In addition, exposure to one seed-treatment, fluquinconazole, was quantified by measuring residues of the fungicide in the stomach, liver, and intestine. The wood mouse, Apodemus sylvaticus, was the dominant species caught on the fields and the only species found to have consumed measurable quantities of seed. Voles, Microtus agrestis and Clethrionomys glareolus, were caught in small numbers, almost exclusively in the field hedge, and showed no evidence of having consumed seed. Stomach-contents analysis revealed that more than 80% of animals trapped in the hedge adjacent to the field had consumed no wheat seed, whereas 98% had consumed less than 10% (by stomach volume). Ninety percent of animals trapped on the field had consumed seed, although 90% of these animals had less than 20% seed in the stomach. Residues of the fungicide in the stomach, intestine, and liver were lower than would be expected for the amount of seed consumed, possibly because of dehusking of the seeds by mice. The relevance of these findings when assessing exposure (and risk) posed by seed treatments to wild mammals is discussed.