Effects of single and mixed infections with wild type and genetically modified Helicoverpa armigera nucleopolyhedrovirus on movement behaviour of cotton bollworm larvae

Naturally occurring insect viruses can modify the behaviour of infected insects and thereby modulate virus transmission. Modifications of the virus genome could alter these behavioural effects. We studied the distance moved and the position of virus‐killed cadavers of fourth instars of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) infected with a wild‐type genotype of H. armigera nucleopolyhedrovirus (HaSNPV) or with one of two recombinant genotypes of this virus on cotton plants. The behavioural effects of virus infection were examined both in larvae infected with a single virus genotype, and in larvae challenged with mixtures of the wild‐type and one of the recombinant viruses. An egt‐negative virus variant caused more rapid death and lower virus yield in fourth instars, but egt‐deletion did not produce consistent behavioural effects over three experiments, two under controlled glasshouse conditions and one in field cages. A recombinant virus containing the AaIT‐(Androctonus australis Hector) insect‐selective toxin gene, which expresses a neurotoxin derived from a scorpion, caused faster death and cadavers were found lower down the plant than insects infected with unmodified virus. Larvae that died from mixed infections of the AaIT‐expressing recombinant and the wild‐type virus died at positions significantly lower, compared to infection with the pure wild‐type viral strain. The results indicate that transmission of egt‐negative variants of HaSNPV are likely to be affected by lower virus yield, but not by behavioural effects of egt gene deletion. By contrast, the AaIT recombinant will produce lower virus yields as well as modified behaviour, which together can contribute to reduced virus transmission under field conditions. In addition, larvae infected with both the wild‐type virus and the toxin recombinant behaved as larvae infected with the toxin recombinant only, which might be a positive factor for the risk assessment of such toxin recombinants in the environment.     

Dutch observation scales to assess cognitive abilities of the aged

Assessment of complex geriatric health problems by nurses is important for diagnosis, especially assessment of cognitive functioning through daily observations. However, it is unclear which Dutch observation scales are available to assess cognitive abilities. In this study, we present an overview of these scales. A systematic review was performed. Beforehand we determined criteria for inclusion of scales and we searched through Dutch and English databases up till May 2005. Thirteen behavioural observation scales were found. The number of dimensions of cognitive functioning assessed in the scales varied greatly, from two to eight in number. Memory and psychomotor behaviour were always included; consciousness and thinking were frequently included, while alertness, perception, executive functions and language were least included. Extensive assessment of cognitive functioning is highly relevant for a geriatric hospital ward in which patients are admitted for diagnosis. Of all scales that we traced, the A-one is the most extensive: all eight dimensions are included. Little is known about the potential for using the A-one scale in nursing practice; further exploration is indicated. For now, nurses should become acquainted with the different dimensions of cognitive functioning and start to integrate observations in these dimensions in their reporting.