Altruistic self‐removal of health‐compromised honey bee workers from their hive

Social insect colonies represent distinct units of selection. Most individuals evolve by kin selection and forgo individual reproduction. Instead, they display altruistic food sharing, nest maintenance and self‐sacrificial colony defence. Recently, altruistic self‐removal of diseased worker ants from their colony was described as another important kin‐selected behaviour. Here, we report corroborating experimental evidence from honey bee foragers and theoretical analyses. We challenged honey bee foragers with prolonged CO₂ narcosis or by feeding with the cytostatic drug hydroxyurea. Both treatments resulted in increased mortality but also caused the surviving foragers to abandon their social function and remove themselves from their colony, resulting in altruistic suicide. A simple model suggests that altruistic self‐removal by sick social insect workers to prevent disease transmission is expected under most biologically plausible conditions. The combined theoretical and empirical support for altruistic self‐removal suggests that it may be another important kin‐selected behaviour and a potentially widespread mechanism of social immunity.     

Habitat selection at multiple spatial scales by foraging Glossy Black‐cockatoos

Abstract: Habitat selection among vertebrates entails decision making at a number of spatial scales. An understanding of factors influencing decisions at each of these scales is required for the effective management of wildlife populations. This study investigates the foraging ecology of a population of Glossy Black‐cockatoos in central New South Wales. We took advantage of the characteristic feeding sign produced by Glossy Black‐cockatoos to examine factors influencing habitat selection at multiple spatial scales. Birds preferred to forage at sites where food was abundant and avoided open sites where the predation risk may be greater. Their two food species, Allocasuarina diminuta and Allocasuarina gymnanthera, differed in profitability (kernel intake rate as measured by the ratio of seed weight to total seed and cone weight), as did trees within a species. Both species were utilized extensively, although foraging intensity was greater at sites where the more profitable species was present. In order to maximize their food intake, birds selected individual trees on the basis of cone abundance and profitability. Cones produced in the previous year were preferred.     

An artificial intergeneric hybrid derived from sexual hybridization between the distantly related Arabidopsis thaliana and Pachycladon cheesemanii (Brassicaceae)

An artificial intergeneric hybrid derived from sexual hybridization between Arabidopsis thaliana (female) and Pachycladon cheesemanii (male) is characterized and formally named as ×Pachydopsis hortorum. A hybrid origin for ×Pachydopsis is supported by a chromosome number of 2n = 15, with this comprising haploid gametes from A. thaliana (n = 5) and P. cheesemanii (n = 10). DNA fingerprinting using amplified fragment length polymorphism data also confirmed the parentage of the hybrid, as it comprised the additive total of all of the fragments scored for P. cheesemanii and most of those scored for A. thaliana. ×Pachydopsis is a robust perennial herb with numerous leafy rosettes and long inflorescences like P. cheesemanii, and floral parts that are intermediate between the parents. ×Pachydopsis produces sterile pollen. Female function of ×Pachydopsis is partially normal, with the pollen of A. thaliana and several species of Pachycladon readily germinating on the stigma, and pollen tubes growing down the style and transmission tissue into the ovary. No seed was formed from these pollinations, although one embryo developed but subsequently aborted at the torpedo stage. Colchicine was used to induce polyploid inflorescences, and these were confirmed by the size and density of the stomata and pollen diameter. Flowers from the polyploid inflorescences of ×Pachydopsis were backcrossed with A. thaliana Landsberg erecta and 11 seeds were produced. Four backcross hybrid plants were raised and two of these had a chromosome number of 2n = 20, consistent with a haploid gamete (n = 15) from polyploid × Pachydopsis being fertilized by a haploid pollen gamete (n = 5) from A. thaliana Landsberg erecta. Polyploid × Pachydopsis flowers backcrossed with P. cheesemanii and crossed with P. novae‐zelandiae did not produce any seeds. The partially fertile intergeneric hybrid described here between Arabidopsis and Pachycladon is remarkable in that, although the two genera occur in an Arabidopsoid clade, they are separated by a reasonable phylogenetic distance. This relationship suggests that Pachycladon and ×Pachydopsis have the potential to be employed in the study of evolutionary and ecological processes using the wide array of Arabidopsis resources. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 533–544.     

Effects of fertilization and herbicides on growth of young loblolly pine and infestations of Nantucket pine tip moth（Lepidoptera： Tortricidae）

A 2-year-old pine plantation was selected to receive treatments of fertilizers and herbicides to evaluate effects on Nantucket pine tip moth infestations and the tree growth parameters of height, diameter and volume increment. Nitrogen and phosphorus fertilizers, and hexazinone and sulfometuron methyl herbicides were used in creating six treatments： （i） control; （ii） phosphorus; （iii） nitrogen and phosphorus; （iv） phosphorus and herbicide; （v） nitrogen, phosphorus and herbicide; and （vi） herbicide. Treatments were applied in 1987 and 1988. In 1987, trees treated with nitrogen, phosphorus and herbicide had significantly greater height, diameter and volume growth than trees not receiving fertilizer treatments, but did not have significantly higher tip moth infestations than control trees. Treatments receiving phosphorus only had much lower tip moth infestation rates than other treatments except nitrogen and phosphorus. In 1988, tip moth infestations were uniformly low, with no differences in treatment effects observed.