Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes

Closed for proposals

Project Type

Coordinated Research Project

Project Code

D41026

CRP

2126

Approved Date

3 September 2015

Status

Closed

Start Date

18 March 2016

Expected End Date

17 September 2021

Completed Date

10 November 2021

Participating Countries

Argentina
Austria
Bangladesh
Canada
Chile
China
Guatemala
India
Israel
Mauritius
New Zealand
South Africa
Syrian Arab Republic
Tunisia
United States of America

Description

Lepidoptera are key pests that require control to avoid significant losses in many cropping systems worldwide. Failure to control key species can result in crop losses and jeopardise the economics of production. Many major lepidopteran pests are also undergoing geographical range expansion. Control options exist for moth pests but most have issues of cost, efficacy or non-target impacts. For example, while insecticides are widely used, there is increasing opposition to residues on food and in the environment. The sterile insect technique (SIT), which involves mass rearing and release of sterile insects to overflood a wild population of the pest, has been used successfully against a number of moth species. However, despite successes, the wider development and deployment of SIT has important issues that need further investigation.  Previous coordinated research projects (CRP) have addressed a number of constraints. Despite excellent progress by a previous CRP, there remains a need for progress in a number of practical areas that limit expansion of SIT for Lepidoptera. Quality can be badly degraded during many processes involved with the mass rearing, handling and release of sterile insects. These processes would be just as important for programs using other sources of sterility than irradiation, from transgenic, RNAi or other novel approaches. Processes which need to be improved and tied to field performance of the insects include: improved rearing and maintenance of colonies based on selection for favourable behaviours, better collection and irradiation methods to enhance results, the application of two-sex or male-only release strategies, improved handling, transport and release methods, practical and effective methods for quality assessment, and better deployment strategies to improve cost-effectiveness and outcomes. A new CRP is proposed to enable collaborators in Member States to benefit from the expansion of the SIT concept to target destructive and invasive lepidopteran species. This objective will be met by:1. Determining the impact of different rearing parameters and behavioural traits that have an impact on competitiveness of sterile moths, by correlation of laboratory and semi-field  and open-field performance2. Determining the impact of adult and pupal collection and irradiation methods on field competitiveness 3. Determining the effect of sterile females on population suppression4. Determining best practice methods of handling, transporting and releasing sterile moths to maintain field competitiveness 5. Determining the relative effectiveness of different methods for assessing quality and performance of sterile and wild moths 6. Developing best practice deployment of sterile insects in relation to hotspots, taking into account moth competitiveness and field performance. 

Objectives

To provide the basis for agricultural food security and safety through long term area-wide integrated pest management of key moth pests with prospects for SIT application, focussing on the field competitiveness of sterile moths.

Specific objectives

Deployment strategies. Develop best practice deployment of sterile moths in relation to hotspots, taking into account insect quality and performance.

Handling, Transporting and Release. Determine best practice methods of handling, transporting and releasing sterile moths to maintain field competitiveness.

Two-sex or male-only release. Determine the relative effects of sterile males and females on population suppression, and the potential for the efficient separation of sexes.

Methods for Quality Assessment. Determine the relative effectiveness of different methods for quality assessment and performance of sterile and wild moths.

Collection and irradiation methods. Determine the impact of adult and pupal collection and irradiation methods on field competitiveness.

Rearing and Behaviour. Determine the impact of different rearing parameters and behavioural traits that have an impact on competitiveness of sterile moths, by correlation of laboratory and semi-field and open-field performance.

Deployment strategies. Develop best practice deployment of sterile moths in relation to hotspots, taking into account insect quality and performance.

Handling, Transporting and Release. Determine best practice methods of handling, transporting and releasing sterile moths to maintain field competitiveness.

Two-sex or male-only release. Determine the relative effects of sterile males and females on population suppression, and the potential for the efficient separation of sexes.

Methods for Quality Assessment. Determine the relative effectiveness of different methods for quality assessment and performance of sterile and wild moths.

Collection and irradiation methods. Determine the impact of adult and pupal collection and irradiation methods on field competitiveness.

Rearing and Behaviour. Determine the impact of different rearing parameters and behavioural traits that have an impact on competitiveness of sterile moths, by correlation of laboratory and semi-field and open-field performance.

Impact

Moth quality and competitiveness are the most important prerequisites for successful SIT programmes. Important factors and parameters were studied in this CRP that were not very well understood but that may have had a significant impact on moth competitiveness. Examples were the effect of chilling, variations in temperature regimes, different diet components, radiation and its effect on pheromone titers and clock genes, radiation hormesis to improve moth quality etc. Better knowledge obtained during the CRP on these parameters will allow the development of methods to address some of these issues and obtaining better quality moths.
Other parameters related to handling and release were likewise studied in this CRP, e.g. the effect of releasing moths with drones compared to ground releases on moth quality provides important guidelines for future release strategies. In addition, first data were obtained in the laboratory indicating that the release of sterile females and males brings benefits to programmes and would make the development of genetic sexing strains obsolete.
Finally, a new F1 sterility strategy was tested (mating of P sterile males with fertile females, hatching of the F1 eggs and ultimate release of the untreated but sterile F1 males) in field cages with very encouraging results. This would make F1 sterility approaches possible for those organizations that have no radiation facility on site

Relevance

Mass-rearing and release of high-quality insects is at the core of agency programmes in SIT and other approaches to biological control. Lepidoptera are among the most damaging insect pests on this planet with some of them developing resistance to existing or even new insecticides in a few generations. The programmes against the codling moth in Canada, the false codling moth in South Africa, the pink bollworm in the US and Mexico and several other programmes have clearly indicated the potential of the SIT as an efficient control tactic against these pests. The results of this CRP will contribute to making some of these programmes more efficient and cost effective and will allow others to be initiated.

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