Wet litter – factors associated with the shed micro-environment and litter properties

Wet litter in meat chicken sheds occurs as the result of multiple, interrelated causes. This paper discusses some of the sources of water in meat chicken sheds, the properties of litter and the contribution of the shed micro-environment. By increasing awareness of the factors associated with wet litter, it will empower the chicken meat industry with knowledge to identify causes and address local incidences through improved litter management. In general, wet litter will be caused by excess water going into the litter, insufficient evaporation and/or limited water holding capability of the litter. Some strategies to improve the effectiveness of ventilation to maintain litter dryness are discussed

Influence of phosphine resistance genes on flight propensity and resource location in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae): the landscape for selection

Phosphine resistance in Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) has evolved through changes to enzymes involved in basic metabolic pathways. These changes impose metabolic stress and could affect energy-demanding behaviours. We therefore tested whether phosphine resistance alleles impact the movement of these insects in their quest for new resources. We measured walking and flight parameters of four T. castaneum genotypes: (1) a field-derived population, (2) a laboratory cultured, phosphine-susceptible reference strain, (3) a laboratory cultured, phosphine-resistant reference strain, and (4) a resistant introgressed strain that is almost identical genetically to the susceptible population. The temporal pattern of flight was identical across all populations, but resistant beetles took flight significantly less, walked more slowly, and located resources less successfully than did susceptible beetles. Also, the field-derived beetles (proved not to be carrying resistance genes) walked significantly faster and more directly towards food resources, and had a higher propensity for flight when compared to the susceptible laboratory beetles. These negative effects suggest survival of beetles with the resistance alleles will be compromised should they leave phosphine application sites. The field for selection therefore extends beyond the site at which phosphine fumigant imposed its effect, and other mutations are also likely to be affected in this way.