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Image copyright: Whitney Cranshaw, Colorado State University, Bugwood.org

Lettuce

Map icon France (South)
Arthropod Pests

Comparing methods of releasing biocontrol (Chrysoperla) to control aphids in lettuce

Partner(s) : CTIFL

Performance assessment

The aim of the trial is to compare a biological control strategy for aphids on lettuce using a mass release of Chrysoperla (pulverisation of eggs) with a conventional release strategy. The aim will also be to see whether the introduction of flower strips can optimise chrysoperla release and management of aphids.

Common name Scientific name Pest type

Aphid

Macrosiphum euphorbiae

Arthropod Pests

Aphid

Nasonovia ribisnegri

Arthropod Pests

Aphid

Aulacorthum solani

Arthropod Pests

Standard practice: standard release of Chrysoperla (larvae) and use of spirotetramat two weeks after planting

ADOPT-IPM solution: pulverization (spraying) of eggs on the lettuce

Factor A: release strategy of Chrysoperla with 3 modalities (1 per tunnel)

  1. No Chrysoperla
  2. Standard release of larvae
  3. Pulverization of eggs

Factor B: presence of flower strips with 2 modalities (each tunnel is divided into 2 parts)

  1. Presence
  2. Absence

6 modality pairs

Replication

2 replicates of the trial over time
Plot size

3 unheated tunnels (160m2 each)
Trial Duration

Planned start date: March 2024

Planned end date: October 2024

Location

South of France, Baladran Center, CTIFL 751 chemin de Balandran, 30127 Bellegarde

Randomization Procedure

No randomisation, 1 tunnel per release strategy

Data Collection

Number of aphids, Number of Chrysoperla

Statistical Methods

Poisson distribution model for counting variables

Overall Performance

Packages are compared by their Performance (displayed in the bar charts and summarised by the Utility score) and their Pesticide Load Index (PLI). Higher Performance/Utility and lower PLI indicate more favourable results.

Compare Packages

Package Utility Pesticide Load Index

Baseline

90%

-

Adopt-IPM

71%

-

Summary

The ADOPT-IPM package was not as effective overall as the Current Commercial Practice (CCP). This was largely due to comparatively higher losses, higher direct costs, alongside greater time and management and coordination requirements.

Performance by indicator

Compare Packages
Package Utility

Baseline

95%

ADOPT-IPM

70%
Notes
For the ADOPT package, the trial results showed reasonable protection from losses but medium confidence reflected variability in the result due weather, skill, etc. Results become more acceptable for organic production where some level of low infestation is tolerated.

Compare Packages
Package Utility

Baseline

74%

ADOPT-IPM

98%
Notes
For CCP the slightly increased physical risk compared with the ADOPT packages was attributable to physical discomfort for PPE required for pesticide applications. For the ADOPT package physical risks were negligible.

Compare Packages
Package Utility

Baseline

74%

ADOPT-IPM

50%
Notes
For CCP, the costs are predictable and well accepted by grower though Spirotetramat is more expensive than other conventional pesticides. In the ADOPT package, CBAs are more expensive (double or triple cost). Flower strip seeds have costs. Flower strips take up growing area. Flower strip irrigation and weeding could add management costs. Chrysoperla costs is more significant that flower strips

Compare Packages
Package Utility

Baseline

98%

ADOPT-IPM

98%
Notes
In the ADOPT package, flower strips enhance natural systems

Compare Packages
Package Utility

Baseline

95%

ADOPT-IPM

50%
Notes
For CCP, scouting can increase time and management requirements, hence not VH confidence and not everyone uses pest scouting. For the ADOPT package, scouting, planting. purchasing, managing flower strips add to requirements. Extra management requirements may put some growers off adoption

Compare Packages
Package Utility

Baseline

98%

ADOPT-IPM

30%
Notes
None are required for CCP however the ADOPT package is dependent on fresh Chrysoperla egg availaibity and extension services. Medium confidence in ADOPT rating was based on some organic growers may already be experienced in the required methods but new adopters would have higher coordination needs and greater dependency on extension