Pathogenicity test of the fungus Aspergillus
clavatus on aphid Acyrthosiphon pisum
(Aphididae)
SEYE Fawrou1,2, BAWIN Thomas2, DELVIGNE Frank3, FRANCIS Frédéric2
1- U.E.R.BV, Laboratory of Reproductive Biology, Department of Animal Biology, Faculty of Science and Technology,University Cheikh Anta Diop of Dakar, PO Box 5005, Dakar Fann, Senegal
2- Department of Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés 2, B-5030 Gembloux, Belgium
3- Bio-Industries Unity, University of Liège-Gembloux Agro-BioTech. F.R.S-FNRS., Passage des Déportés, 2. B-5030 Gembloux, Belgium.
Acyrthosiphon pisum (Homoptera : Aphididae) called also pea aphid is a pest of many cultivated and wild plants, but also a vector of some viral diseases. For the control of these pests, the most widely used methods are physical, chemical and more recently integrated approches that include biological control. With the use of pathogenic agents against insects, entomopathogenic fungi are among the most promising. Their use against aphids should be beneficial in biological control.
The aim of this study is to demonstrate the possibility of using an entomopathogenic strain of Aspergillus clavatus (already test on mosquitoes) against pea aphid.
I- Introduction
III- Materials and methods
II- Objectives
IV- Results
2b- On the other hand, doses ranging from 104 to 106 conidia / ml were applied on the individual young plants before deposing 20 adult aphids. 2a- On the one hand, 20 aphids
were in contact with different concentrations ranging from 102 to 104conidia/cm2.
3- In the two cases, aphids are incubated at 8D/16L photoperiod, and 25oC. The mortality were recorded daily and corrected with Abbott formula.
1- Fungus was grown on wheat bran. The spore content of the aqueous formulation was determined by
haemocytometer.
IV- Results
0 5,26 5,26 10,52 31,57 0 0 10 20 30 40 50 6,14 E2 8,19 E2 1,2 E3 2,4 E3 2,4 E4 Control
Percent of aphid mortality 24 h after fungal treatment in the Petri dishes
6,6 6,6 10 0 20 0 13,3 23,3 23,3 40 43,3 0 27,5 44,8 31 48,27 55,1 5 31 51,7 51,7 62 79,3 5 34,5 65,5 58,6 72,4 89,6 5 0 10 20 30 40 50 60 70 80 90 100
3,90E+04 5,20E+04 7,80E+04 1,50E+05 1,50E+06 Control Doses (conidia/ml)
Percent of aphid mortality whithin 5 days after conidial treatment on the plants
D1
D2
D3
D4
D5
In the Petri dishes, Aphids were infected with fungus by contact. In 24h, mycelia have penetrate the cuticle and fungal tubes appear on the dead aphid (a). Sporulation continues within 48 h (b), and 72 h (c) after incubation at 75% RH showing early formation of A. clavatus conidia. Also, the conidial attack can stop mycosis of the aphids causing death (d). haemocytometer.
24th International Congress of Entomology, Daegu, Korea: International Congress of Entomology (ICE) August 2012
Conclusion: The entomopathogenic fungus Aspergillus clavatus is susceptible against A. pisum. Investigations should be made to study its action on the reproduction. Therefore, it could be introduced along with other fungi found in the literature as a biological control agent against aphids.
Aphids in contact with treated plants are infected. Mycelia that appear within 24 hours (e) continue to sporulate in 48 and 72 h (f and g).
1- Fawrou Seye 1(a),Oumar Faye 2(b), Mady Ndiaye 1(c), Ebrima Njie 3(d) and José Marie Afoutou 2(e), 2008. Pathogenicity of the fungus, Aspergillus clavatus, isolated from the locust, Oedaleus senegalensis, against larvae of the mosquitoes Aedes aegypti, Anopheles gambiae and Culex Quinquefasciatus. Journal of Insect Science: Vol. 9 | Article 53
2-CHEN Chun & FENG Mingguang, 2002. Evidencefor
transmission of aphid
pathogenic fungi by migratory flight of Myzus persicae alates Chinese Science Bulletin Vol. 47 No. 23