Sustainable management of coffee green scales in Papua New Guinea

The project has the following objectives:

1. Assess the nature of the problem to understand a) the biological factors influencing scale insect infestations (occurrence of different scales, lifecycle, extent/pattern of colonisation, role of ants in protecting/encouraging infestations, status of parasitoids released in 1986, b) the potential for use of additional biocontrol agents

2. Assess and understand the socio-economic constraints to fostering participatory involvement and uptake of integrated pest management by smallholders.

3. Develop additional IPM approaches (including possible strategic use of pesticides and ant control strategies) that accommodate smallholder needs and aspirations and optimise the chance of success of biological approaches.

2. Project initiation
Baker and Murphy travelled to PNG Aiyura in October 2007 to hold start-up workshops.
Objectives of the visit were:
1) To formally open the project with all main project partners
2) To agree key milestones within main project objectives
3) Establish sampling methods for CGS and socio-economic surveys
4) Establish priorities and methodologies for ecological studies
5) Establish a viable work-plan for the first 6 months of the project
6) Establish responsibilities for specific work-plan actions

An intention of the project is to capitalise on synergies with the two other ACIAR-funded coffee projects being carried out at the same time: ASEM/2004/042 on marketing and PHT/2004/017 on postharvest quality management. To this end a joint meeting was held at Aiyura in February 2007 under the facilitation of Tony Marsh.

The joint meeting: clearly the combining of the socio-economic surveys, together with the work already carried out by Batt & Murray-Prior are the main area of synergy for the present project. This was subsequently discussed at length with CIC personnel and it is clearly established that parts of socio-economic surveys serve all projects. From the discussions, it seems clear from Batt & Murray-Prior's work that the socio-economic limitations on coffee production presently dwarf any biotic or abiotic constraints. Transport and labour shortages, combined with a significant coffee theft problem in some areas (berries stolen
from trees) must conspire to limit smallholders' interest in investing more time in coffee to increase yields by controlling pests and diseases for example.

What the socio-economic state of affairs may mean for the present project:
* Costly and/or time-consuming ways of controlling CGS are very unlikely to be adopted; quite probably even a very simple form of IPM could be beyond the great majority of smallholder farmers - even if substantial efforts were put into farmer training, it seems unlikely that they would adopt any measures that involved extra work, since other constraints are so great. This suggests that the emphasis on classical biocontrol is the best policy to adopt. ??CGS seems to presently have the most noticeable effect on seedlings, which suffer a high mortality through CGS attack. If CGS control by classical biocontrol is successful, coffee production would rise and replanting costs would fall for no additional farmer inputs. If later campaigns to replant coffee were to be realized, effective control of CGS would be a boon.

* When coffee berry borer (CBB) arrives in PNG (it could be soon, it is very close to the PNG border) farmers at all but the highest altitudes will have to invest more time in their crop if they are to get any sort of return from growing coffee. This will entail more pruning to control the size of trees to make them easier to manually control the CBB infestations. If CGS is not under control, it will most likely cause great difficulties by attacking the new growth flushes.

The CGS team have made good progress on the survey, have recently hired an entomologist to take charge of rearing and are making progress with preparing stock plants and laboratory facilities to receive future shipments of parasitoids. If work continues to advance on this over the next few months, we should have some good baseline data on socio-economic parameters. Some initial experimental exclusion work could be started to sort out methodological problems.

But efforts should concentrate on making culture facilities ready to receive regular parasitoid shipments with a considerable and compatible stock plant material of citrus and gardenia - i.e. a similar scheme to that successfully employed in Australia. This especially since after Batt et al's socio-economic surveys, biological control seems even more so than before, to be the most viable way of controlling this pest for the smallholder. I.e. there is little chance of any time-consuming or product-based approach being adopted by the majority of smallholder farmers. Curtailed field work during election times should allow plenty of time to concentrate on the improvement of laboratory rearing conditions and analyse the recent survey.

The incidence and impacts of coffee green scales (CGS) and their associated insects were recorded via major surveys in Eastern Highlands Province (EHP) in 2006/2007. The results of this study show that CGS infestations were highest at 1500m, above and below this, infestations were much lower. The impact of this data is not restricted to this project alone, but can be used in conjunction with future studies targeting areas of high infestations.
There is scientific evidence that the removal of ants reduces scale infestations. It is thought that ants provide key services that augment CGS populations. Since 2007 an additional research station study examined the effect of excluding ants on CGS infestation levels. This has shown that excluding ants reduces infestation rates over time.
A survey examining the species diversity, abundance and distribution of ants and CGS has been completed. The mortality of young coffee trees and shoots is greater than mature infested coffee trees. The effect on young trees is compounded when CGS are attended by ants because ants can prevent natural enemies thereby increasing CGS survival leading increased damage. It has become clear that native ant species do not appear to be a major issue. Exotic invasive species appear to be the problem. This could impact on future biological control as some of these ant species maybe very closely associated with CGS and their biocontrol agents. Further investigations will be needed, specifically the provenance of these ant species, their ability to harass CGS predators and to asses the potential for the control of ants.
The intention was to import available parasitoids from Australia and switch them to coffee in the quarantine facility, planned for September 2007. A 'citrus system' should have been ready, but due to a CGS population crash it was not. After reviewing the situation a series of possible causes were identified and have been rectified.
The Aiyura quarantine facility will be the receiving unit for biocontrol agents so a thorough review of its current status was carried out. Whilst it was clear that significant progress had been made the persistent problem of inadequate light and overheating was evident. After extensive reconstruction the resulting facility has been significantly improved in terms of light and temperature control, and can accommodate purpose built cages. Despite excellent progress the facility was still not of a suitable quarantine standard in terms of security. However, structural improvements and procedural changes have been implemented.
Preliminary and large scale socio-economic surveys to examine current control methods, constraints to farmers and available support services were completed in 2006/2007. Participatory extension is the main tool used by PNG farmers. However, there is clearly a lack of knowledge amongst farmers on CGS, especially smallholders. Many farmers were unaware of what CGS was, and as such this lack of knowledge made it difficult to determine control methods and yield loss. This indicates that there had been a shortfall of information from extension programmes. Extension officers are interested in learning, and can be advised on new approaches tailored to local needs.
Both human mediated and natural pathways appear to be involved in CGS spread. Nurseries grow and supply seedlings which happen to be infested with CGS. Simple sanitation could provide clean plants available for farmers. However, another common route is via infested farms where farmers propagate their own seedlings. With the natural spread possibly being mediated via invasive ants, both ecological and anthropogenic issues need to be resolved.
In order to provide more clarity from these surveys a scoping study was conducted in late 2007 to pave the way for more detailed case studies. These principally address; farmer practices, awareness and extension, and incorporate the whole family. The scoping study was conducted on the sites that were identified as high risk zones.
Farmers were first briefed on CGS in 1994, by the Coffee Research Institute. However, limited knowledge and educational material negated its impact such that until recently, farmers were not aware of CGS as a problem. Extension officers also learnt from the previous project surveys and are now able to provide information during the current Participatory Rural Appraisal Programme (PRAP). Recent exposure to awareness material has enabled farmers to identify CGS as a problem such that they discuss CGS with PRAP officers. As such, the PRAP programme has improved the relationship between CIC-Extension and farmers. This programme has helped them to understand CGS and clearly shows that the current extension has great potential.