Application of three entomopathogenic fungi for aphid control

Application of three entomopathogenic fungi for aphid control

Introduction

• Aphids (Homoptera: Aphididae) are sap-sucking insect pests that feed on several plants of agronomical importance • Chemical pesticide application is the most

commonly used method for aphid control • Integrated pest management including

biological control is now promoted • Entomopathogenic fungi are valuable

tools for potential aphid control

Results

1 _{Functional and Evolutionary Entomology – University of Liege (GxABT) – Gembloux (Belgium)} 2 _{Reproductive biology – University Cheikh Anta Diop – Dakar Fann (Senegal)}

3 _{Bio-Industries/CWBI – University of Liege (GxABT) – Gembloux (Belgium)} Email: entomologie.gembloux@ulg.ac.be

Materials & Methods

media in flasks up to sporulation • The solid media were washed with

aqueous solutions containing 0.05% Tween 80 before filtration

• The content of conidia in filtrates was determined by haemocytometer • Doses ranging from 103 _{to 10}7 _conidia/ml

were then sprayed on young plants with 20 adult parthenogenetic aphids • Batches were incubated at a 16L/8D

photoperiod, 25±2°C and 75-80% RH

Survey data

1. Adult mortality was assessed and corrected with Abbott formula in order to determine LD50, LD90 and LT50 values 2. The number of nymphs produced was

daily recorded and expressed as intrinsic growth rate

Objectives

As part of a selection process, 3 new isolated fungal strains (Metarhizium and Aspergillus genus) are tested against Acyrthosiphon

pisum aphids and compared regarding their:

1. insecticidal activity 2. impact on adult’s fitness

Conclusions

1. Fungal isolates induced A. pisum mortality with a similar impact 2. A. clavatus infection statistically seemed to alter adults’ fitness  This suggests that these fungi may be candidates for aphid control

Perspectives

• Further investigations should be made in order to assess their host range specificity

• Toxic metabolites leading to death have to be identified and their safety towards non-target organisms confirmed

• Their persistence in the environment as well as the compatibility with over means of aphid control must be verified in a view of a broad integrated pest management

65th International Symposium on Crop Protection – May 2013 – Ghent University Aspergillus clavatus

Metarhizium anisopliae

Metarhizium sp. Acyrthosiphon pisum

0 10 20 30 40 50 60 70 80 90 100 Mo rta lity + SD (% ) 10^3 10^4 10^5 10^6 10^7

1. Acyrthosiphon pisum aphids mortality after 5 days of exposure to Metarhizium and Aspergillus strains depending on tested doses

Metarhizium sp. LD50 = 1.23 x 103 LD90 = 1.34 x 107 *LT50 = 2 days M. anisopliae LD50 = 3.67 x 103 LD90 = 9.71 x 107 *LT50 = 4 days Aspergillus clavatus LD50 = 4.95 x 102 LD90 = 5.65 x 107 *LT50 = 3 days

Metarhizium sp. M. anisopliae Aspergillus clavatus

* * * Spores/ml 103 104 105 106 107

2. Acyrthosiphon pisum aphids growth rate after 5 days of exposure to Metarhizium and Aspergillus strains depending on tested doses

-0,05 0,00 0,05 0,10 0,15 0,20 G ro w th ra te + SD Control 10^3 10^4 10^5 10^6 10^7 Spores/ml Control 103 104 105 106 107