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Start Over Creator Niemeyer, Hermann M.

1. Pattern of cell punctures by the aphid Sitobion fragariae (Sternorrhyncha: Aphididae) and cell arrangement in the leaf tissues of wheat, Triticum aestivum

Creator:
Ramírez, Claudio C., Olea, Nancy, and Niemeyer, Hermann M.
Type:
article, model:article, and TEXT
Subject:
Aphididae, Sitobion fragariae, cell punctures, EPG, leaf tissue, and wheat
Language:
English
Description:
The pattern of cell punctures in the electrical penetration graph was studied from the start of a probe leading to the first phloem phase by the aphid Sitobion fragarine (Walker) (Sternorrhyncha: Aphididae) on two cultivars of the wheat, Triticum aestivum L., differing in hydroxamic acid concentration. In addition, the spatial arrangement of cells in the leaf of the host plant was histologically observed and the number of cells between the epidermis and phloem counted. The results suggest a feeding deterrent effect of hydroxamic acids and a constant styler puncturing activity into plant cells.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Sequestration of aristolochic acids from meridic diets by larvae of Battus polydamas archidamas (Papilionidae: Troidini)

Creator:
Pinto, Carlos F., Urzúa, Alejandro, and Niemeyer, Hermann M.
Type:
article, články, model:article, and TEXT
Subject:
Zoologie, entomologie, Lepidoptera, Papilionidae, Battus polydamas archidamas, Aristolochia chilensis, aristolochic acids, sequestration of toxins, uptake of toxins, 2, and 59
Language:
English
Description:
Larvae of the butterfly, Battus polydamas archidamas (Papilionidae: Troidini) feed exclusively on aristolochic acid (AAs)-containing Aristolochia species (Aristolochiaceae). The distribution of sequestrated AAs in the tissues (body, integument and osmeterial secretions) of B. polydamas archidamas larvae during their development, when fed on a meridic diet containing either a higher or lower concentration of AAs (AAI and AAII) than occurs naturally in the aerial tissues of their host plant, was determined. Accumulation of AAs in the body and integument was proportional to the weight of larvae and greater in the larvae that fed on the diet containing the higher concentration of AAs. Phenolic AAs (AAIa and AAIVa) not present in the diets were found in all larval tissues examined. Integument and body extracts had a higher AAI/AAII ratio than in the original diet and also a relatively high AAIa/AAIVa ratio, suggesting a preferred AAII to AAIa transformation in those larval tissues. In the osmeterial secretion, the value of the AAI/AAII ratio was similar to that in the diets and the AAIa/AAIVa ratio close to 1, which suggests that hydroxylation of AAI to AAIVa and of AAII to AAIa occur to similar extents. The higher accumulation of AAs and the relatively higher proportion of AAI, one of the most toxic AAs, in the integument, suggest that their role is to deter attacks by natural enemies. and Carlos F. PINTO, Alejandro URZÚA, Hermann M. NIEMEYER.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. The Argentine ant, Linepithema humile (Hymenoptera: Formicidae: Dolichoderinae) is sensitive to semiochemicals involved in the spacing behaviour in the bird cherry-oat aphid Rhopalosiphum padi (Sternorrhyncha: Aphididae)

Creator:
Córdova-Yamauchi, Leslie, Gianoli, Ernesto, Quiroz, Andrés, and Niemeyer, Hermann M.
Type:
article, model:article, and TEXT
Subject:
Aphididae, Formicidae, semiochemicals, spacing behaviour, olfactometry, Argentine ant, and aphid tending
Language:
English
Description:
The behavioural response of an aphid-tending ant, the Argentine ant Linepithema humile, to semiochemicals related with spacing behaviour in the aphid Rhopalosiphum padi (L.) was evaluated. The compounds involved were 6-methyl-5-hepten-2-one (MHO), 6-methyl-5-hepten-2-ol (MHOH), and 2-tridecanone (2-T). Hexane solutions of these semiochemicals either singly or mixed, and extracts obtained by trapping volatile compounds from wheat seedlings either alone or infested with two different densities of aphids were used as stimuli in olfactometric bioassays. Ants showed attraction to volatile extracts from plants infested at both densities, and slightly preferred volatile compounds from lightly over heavily infested plants in a choice test. On the other hand, while a dose-dependent repellence response was elicited by the naturally-occurring mixture of MHO, MHOH and 2-T, single compounds did not elicit significant responses in olfactometric bioassays. The function of these semiochemicals as indicators of quality of the aphid colonies as trophic resource to ants is discussed.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public