Habitat usage of Rattus rattus in Australian macadamia orchard systems: implications for management

doi:10.1016/S0261-2194(98)00029-5

Crop Protection

Volume 17, Issue 4, June 1998, Pages 359-364

https://doi.org/10.1016/S0261-2194(98)00029-5 Get rights and content

Abstract

Rattus rattus is the main species responsible for causing damage to Australian macadamia crops and previous studies have shown that these animals utilise both the orchard and adjacent non-crop habitats. Australian macadamia orchards are a three compartment system consisting of the orchard (tree and ground layers) and the adjacent non-crop habitat. The development of an effective management strategy to reduce damage due to rodents requires an understanding of the utilisation of and interactions between the different habitat compartments of the system. The use of tetracycline as a biomarker revealed a strong two-way interaction by rodents between the orchard and the temporally stable adjacent habitats. This interaction was consistent within orchards in Queensland and New South Wales. Nut damage was found to occur within the canopy of the tree indicating that the interaction occurs between the adjacent habitat and the tree layer of the orchard. Capture and biomarker studies suggest that the observed bi-directional movement of rodents between the orchard and the adjacent habitat actually consist of two separate processes: bi-directional foraging into the edge of the orchard by individuals from the large population stratum in the adjacent habitat and uni-directional dispersal and accumulation of individuals from the orchard interior into the adjacent habitat. As the adjacent habitat supports high numbers of rodents and is implicated in both processes, that is, as a source for foragers which results in high edge damage and as a sink for orchard dispersers, it is central to the damage process and should be the focus for control programs.

References (7)

M.E. Tobin et al.
Bait placement and acceptance by rats in macadamia orchards
Crop Protection
(1997)
J. White et al.
The role of adjacent habitats in rodent damage levels in Australian macadamia orchard systems
Crop Protection
(1997)
G. Caughley et al.

There are more references available in the full text version of this article.

Cited by (20)

Population demography and fecundity do not decline with habitat fragmentation in the rainforest tree Macadamia integrifolia (Proteaceae)
2010, Biological Conservation
Citation Excerpt :
The negative relationship observed between addition of foreign materials and plant density may be due to an associated reduction in suitable seedling establishment sites and/or an increase in safe sites for predators. In studies into nut predation by Rattus rattus in commercial macadamia orchards, the highest damage levels were recorded for orchards adjacent to habitat that provided a high degree of aerial and lateral cover (Horskins et al., 1998; Elmouttie and Wilson, 2005). An association between foreign materials and reduced seedling recruitment is supported by the observed positive relationship between foreign materials and plant height.
Habitat fragmentation is often associated with reduced levels of fitness and local extinction of plant species, and consequently poses a major threat to the persistence of species worldwide. The majority of demography-based fragmentation studies to date have focussed primarily on fragmentation impacts on individual plant fecundity. Here we investigate the impact of habitat fragmentation on the demography (plant height classes and density) and key population dynamic processes for the rainforest tree species Macadamia integrifolia (Proteaceae). Raceme and fruit production and seedling emergence across fragmented sites exceeded that in more intact sites with no apparent difference in short-term mortality rates. Fecundity of flowering trees did not appear to be affected by fragmentation. Instead, overall reproductive output in fragmented sites was enhanced relative to undisturbed sites due to a higher proportion of reproductively active individuals. The probability of flowering and fruiting was negatively correlated with the projected foliage cover (PFC) surrounding individual trees, and average PFC was significantly lower in small and medium fragments, suggesting light availability as a potential contributor to the trends observed here.
This study demonstrates that the short-term effects of habitat fragmentation on population viability may not necessarily be detrimental for some species, and highlights the importance of assessing not only the fecundity of flowering individuals but also the proportion of individuals reproducing within fragments.
The potential importance of nut removal by rodents from Australian macadamia orchards
2005, Journal of Environmental Management
Extensive crop damage due to rodents, predominantly the black rat (Rattus rattus) is a major concern to both the Hawaiian and Australian macadamia industries. Within Australian systems, White et al. (1997) indicated the importance of adjacent non-crop habitats in the damage process with damage being directly related to the size and temporal stability of these habitats. It was also suggested that the current estimates of crop loss might be underestimates as R. rattus may remove nuts into adjacent non-crop habitats, however, the economic significance of nut removal was not investigated.
This study has determined that the crop loss due to nut removal is equivalent to the crop loss due to in-crop feeding within the first row of the orchard, with nuts being removed and consumed under the cover provided by weedy adjacent habitats. Previous studies (White et al., 1997; Horskins et al., 1998; White et al., 1998) investigating the impact of rodents on crop damage have ignored the nut removal component of the damage process and hence rodents have a far greater impact on the Australian macadamia industry than previously suggested.
This study also indicates that the cost-benefit of habitat manipulation as a rodent management strategy is much greater than that suggested by Horskins and Wilson (1999). Habitat manipulation is not only a cost-effective means of damage control but is also sustainable, having none of the potentially adverse public health and environmental effects of continual rodenticide use.
Cost-effectiveness of revegetating degraded riparian habitats adjacent to macadamia orchards in reducing rodent damage
2003, Crop Protection
The cost-effectiveness of habitat manipulation as a management strategy for the control of rodent pests in Australian macadamia (Macadamia integrifolia) orchards was investigated in a 3-yr study that combines a pest management strategy with a conservation outcome. The manipulation involved the total removal of exotic weeds from an adjacent non-crop riparian habitat, which harboured a high density of the native rodent, Uromys caudimaculatus, and the planting of species common to an endangered rainforest ecosystem. Over a 3-yr period, orchard trees adjacent to the restored habitat received 50% less rodent damage than trees adjacent to non-manipulated habitats.
A cost–benefit analysis (based on both contractor and farm rates) of the damage reduction obtained after the initial manipulation indicated a break-even point (based on farm rates and a nut in shell price of $2.80/kg) of 3.4 yr. After break-even, this represents an economic benefit to growers that will result in an additional return of approximately $4500 per annum per km of orchard frontage.
Cost-effectiveness of habitat manipulation as a method of rodent control in Australian macadamia orchards
1999, Crop Protection
Previous studies (White et al., 1998) have shown that the manipulation of habitats adjacent to Australian macadamia orchards can result in a reduction in damage due to rodents of up to 65% and that damage was most severe in the first three rows of orchards adjacent to temporally stable large habitats (TSL_1–3) (White et al., 1997). Cost-effectiveness is the ultimate test of any control strategy, as control practices represent a cost to the industry that must be balanced by a benefit to production. The cost-effectiveness of habitat manipulation as a control strategy was determined in 54 macadamia orchard blocks in Queensland and New South Wales that were representative of the range of adjacent habitat types and damage levels found within major growing areas. The financial break-even point of habitat manipulation (whereby costs and benefits were equal) was dependent on the level of damage in TSL_1–3 and ranged between 5 and 15% with a mean of 9%. These levels are well within the range of damage levels that exist within the industry. Where damage in the first three rows of orchards adjacent to TSL habitats ranged between 15 and 25%, habitat manipulation was shown to be cost-effective in all orchard blocks. The cost-effectiveness of habitat manipulation was reduced to 59% of blocks at damage levels of 10% and it was never cost-effective at damage levels of 5% in TSL_1–3. A comparison of the savings from habitat manipulation and current strategies (baiting with anti-coagulant rodenticides) showed that baiting was unlikely to be as cost-effective at damage levels in TSL_1–3 of greater than 5%. It is only when a control strategy has been shown (a) to reduce damage levels in a cost-effective manner and (b) comply with social and ecological constraints, that it can be classed as effective and acceptable for adoption by the industry. Habitat manipulation, as a strategy for the control of rodents in Australian macadamia orchards, has met these requirements.
Impact of contraceptive hormones on the reproductive potential of male and female commensal black rats (Rattus rattus)
2022, Integrative Zoology
Rodent Damage and their Control for Attacking Seeds of Rhamnus cathartica (Buckthorn) Plants in Rural Areas, Upper Egypt
2021, Journal of Plant Protection and Pathology

View all citing articles on Scopus

View full text

Research paperHabitat usage of Rattus rattus in Australian macadamia orchard systems: implications for management

Abstract

Crop Protection

Crop Protection

Research paper
Habitat usage of Rattus rattus in Australian macadamia orchard systems: implications for management