Eustachio Tarasco

Franca de Luca

Monica Oreste

English

Archivio istituzionale della ricerca - Università di Bari

Microbial and Nematode Control  of Invertebrate Pests IOBC-WPRS Bulletin Vol. 129, 2017 pp. 74-76  74   Potential of entomopathogenic fungi and nematodes  against the two cryptic species Parahypopta caestrum  and Cossus cossus in laboratory assays  Eustachio Tarasco, Monica Oreste University of Bari Bari “Aldo Moro” – DiSSPA, Dipartimento di Scienze del Suolo, delle Piante e degli Alimenti, Via Amendola 165/a, 70100 Bari, Italy e-mail: eustachio.tarasco@uniba.it   Abstract: Preliminary assays were performed in laboratory conditions in order to evaluate the infectivity of several entomopathogenic fungi (EPFs) and entomopathogenic nematodes (EPNs) autochthonous strains against P. caestrum and C. cossus larvae. Results revealed the efficacy of these microbial control agents in killing the larvae, although a wide inter- and intra-specific variability in virulence was detected among different microbial strains. Considering the lack of effective chemical control means, the microbial control of the Asparagus moth and the goat moth by EPNs and EPFs reveals promising perspectives and needs further investigations.   Key words: Cossus cossus, Parahypopta caestrum, microbial control   Introduction   Parahypopta caestrum (Hübner) and Cossus cossus (L.) (Lepidoptera, Cossidae) are highly-destructive cryptic pests in Europe. P. caestrum can be considered the key pest of  Asparagus spp. in Italy, due to its high destructiveness and the lack of effective control options available. The soil-borne larvae bore mines into the roots and the shoots, causing the total destruction of plantations after 2-3 years. The goat moth C. cossus (L.) is a wood-boring pest whose larvae bore large galleries under the bark and even deeply into trunks and branches of fruit and forest trees, reducing plant growth and vigour, and causing limbs and branches to fall. Pests residing in cryptic habitats, as insects which bore into the plant tissue (wood-boring insects) or under the bark (bark beetles) or in the soil (wireworms) are very difficult to control because chemical pesticides are not able to reach the target (Gumus et al., 2015). Usually, the only option to reduce infestations is the removal and destruction of infested or injured plants (Gumus at al., 2015). One potential alternative to chemical insecticides for the control of cryptic insects can be the use of  microbial control agents, as entomopathogenic nematodes (EPNs) and fungi (EPFs), because they may be able to penetrate into cryptic habitats and to be horizontally transmitted within the pest populations (Kreutz et al., 2004; Marannino et al., 2007; Demibilio et al., 2010; Ashtari et al., 2011; Gumus et al., 2015).     75    Material and methods   III instar larvae of P. caestrum (collected from infested Asparagus plantation) and C. cossus (from infested cherry orchard) were treated with 5 nematodes (Steinernema feltiae,  S. carpocapsae, S. arenarium, S. affine, H. bacteriophora) and 3 fungal (B. bassiana) entomopathogenic autochtonous strains. The experiment agaist P. caestrum was carried out in pots (16 cm diameter) containing field soil collected from asparagus plantations. In each pot, 5 larvae of P. caestrum were introduced. After 24 hours (all the larvae had deepened in the soil), each pot was inoculated with 100 ml of nematodes (300,000 Ijs) or fungal  (2 × 108 conidia/ml) suspension, while the control pots were treated with 100 ml of sterile water. The pots were then incubated at 25 °C for 7 days, irrigated daily with water in order to avoid the soil drying. The assay agaist C. cossus was carried out in Petri dishes provided, with filter paper and cherry bark pieces. In each dish, 5 larvae were introduced. Larvae were treated with single nematodes (300 Ijs/larva) or fungal (immersion for 20 seconds in  2 × 108 conidia/ml suspension) strain. The Petri dishes were then incubated at 24 °C for  7 days, recording the daily mortality. The following data were recorded: alive larvae, larvae with signs of fungal outgrwoth, larvae infected by nematodes, dead larvae due to other causes (natural mortality). Mortality caused by the entomopathogenic nematodes and fungal strains was confirmed by re-isolation of nematodes and fungi. Data were submitted to the logistic regression and means were then compared with the least-squares means statistics (P < 0.05).   Results and discussion   As shown in Figure 1, all the nematodes and fungal strains affected the Asparagus moth and the Goat moth survival. Steinernema feltiae, M. anisopliae and B. bassiana showed the best performances against both the pests, killing more than the 90% of the treated larvae. Considering the lack of effective chemical control means, the microbial control of the cryptic species by EPNs and EPFs reveals promising perspectives and needs further investigations. Nematodes and fungi are able to penetrate the cryptic habitats because they are living organisms and may be horizontally transmitted by infected hosts; nevertheless, their effectiveness as bio-agents against P. caestrum and C. cossus needs to be confirmed in the field.  76    Figure 1. Effect of EPFs and EPNs on P. caestrum and C. cossus final cumulative mortality.   References   Ashtari, M., Karimi, J., Rezapanah, M. R., Hassani-Kakhki, M. 2011: Biocontrol of leopard moth, Zeuzera pyrina L. (Lep.: Cossidae) using entomopathogenic nematodes in Iran. IOBC-WPRS Bulletin 66: 333-335. Dembilio, O., Quesada-Moraga, E., Santiago-Alvarez, C., Jacas, J. A. 2010: Potential of an indigenous strain of the en-tomopathogenic fungus Beauveria bassiana as a biological control agent against the red palm weevil, Rhynchophorus ferrugineus. Journal of Invertebrate Pathology 104: 214-221. Gumus, A., Karagoz, M., Shapiro-Ilan, D., Hazir, S. 2015: A novel approach to biocontrol: Release of live insect hosts pre-infected with entomopathogenic nematodes. Journal of Invertebrate Pathology 130: 56-60. Kreutz, J., Zimmermann, G., Vaupel, O. 2004: Horizontal transmission of the entomo-pathogenic fungus Beauveria bassiana among the spruce bark beetle, Ips typographus (Col., Scolytidae) in the laboratory and under field condi-tions. Biocontrol Science and Technology 14(8): 837-848. Marannino, P., Santiago-Alvarez, C., De Lillo, E., Quesada-Moraga, E. 2007: Evaluation of Metarhizium anisopliae (Metsch) Sorok. to target larvae and adults of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) in soil and fiber band applications. Journal of Invertebrate Pathology 97(3): 237-44. 

Potential of entomopathogenic fungi and nematodes against the two cryptic species Parahypopta caestrum
and Cossus cossus in laboratory assays

https://ricerca.uniba.it/bitstream/11586/209132/1/2017.%20IOBC%20tblisi.%20Oreste%20%26%20Tarasco.pdf

Potential of entomopathogenic fungi and nematodes against the two cryptic species Parahypopta caestrum and Cossus cossus in laboratory assays

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Archivio istituzionale della ricerca - Università di Bari