Essential oils and Beauveria bassiana against Dermanyssus gallinae (Acari: Dermanyssidae): Towards new natural acaricides.
Essential oils (EOs) and entomopathogenic fungi such as Beauveria bassiana (Bb) strains have the potential to be used as alternative insecticides and acaricides for controlling ectoparasites as Dermanyssus gallinae. These compounds have some limitations in their use: the acaricidal effect of EOs is rapid, but short-lived, whilst that of Bb is delayed, but long-lived. To evaluate the effect of both compounds combined against D. gallinae, the non-toxic dose of Eucalyptus globulus, Eucalyptus citriodora, Thymus vulgaris and Eugenia caryophyllata essential oils were firstly calculated for "native" strains of Bb. Subsequently, the effects of the combination of selected EOs with Bb against nymph and adult poultry red mites (PRMs) was assessed. EO concentrations ranging from 0.0015 to 8% v/v (i.e., nine double dilutions) were used to evaluate their effect on germination, sporulation and vegetative growth rates of native strains of Bb. A total of 1440 mites (720 nymphs and 720 adults) were divided into three-treated group (TGs) and one control group (CG). In TGs, mites were exposed to Bb in combination with the selected EO (TG1), EO alone (TG2) or Bb (TG3) alone. In the CG, mites were exposed to 0.1% tween 80 plus EO solvent (CG). E. globulus and E. citriodora were toxic for Bb in concentrations higher than 0.2% and 0.003% respectively, whilst E. caryophyllata and T. vulgaris were toxic at all concentrations tested against Bb. Based on the results of the toxicity assays against Bb, E. globulus was chosen to be tested as acaricide resulting non-toxic for Bb at concentration lower than 0.4%. Increased mortality of D. gallinae adults was recorded in TG1 than those in other TGs from 4days post-infection (T+4DPI). A 100% mortality of D. gallinae was recorded in adults at T+9DPI and at T+10DPI in nymphs in TG1 and later than T+11DPI in the other TGs. Used in combination with E. globulus, Bb displayed an earlier acaricidal effect towards both haematophagous D. gallinae stages. The combination of B. bassiana and E. globulus at 0.2% might be used for controlling arthropods of medical and veterinary importance as D. gallinae.
Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Italy.
Davide
D
Immediato
Departamento de Imunologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, 50670-420 Recife, Brazil.
Luciana Aguiar
LA
Figueredo
Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Italy.
Roberta
R
Iatta
Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Italy.
Antonio
A
Camarda
Departamento de Imunologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, 50670-420 Recife, Brazil.
Rafaela Lira Nogueira
RLN
de Luna
Dipartimento di Scienze Agrarie, degli Alimenti e dell'Ambiente, Università degli Studi di Foggia, 71121 Foggia, Italy.
Annunziata
A
Giangaspero
Departamento de Imunologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, 50670-420 Recife, Brazil.
Sinval Pinto
SP
Brandão-Filho
Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Italy.
Domenico
D
Otranto
Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, 70010 Valenzano, Italy. Electronic address: claudia.cafarchia@uniba.it.
Claudia
C
Cafarchia
D056810:Acaricides / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D052982:Beauveria / Q000502:physiology*; D005052:Eucalyptus / Q000737:chemistry; D008925:Mites / Q000187:drug effects* / Q000382:microbiology; D009822:Oils, Volatile / Q000008:administration & dosage / Q000494:pharmacology*; D010572:Pest Control, Biological; D010938:Plant Oils / Q000494:pharmacology*; D027842:Syzygium / Q000737:chemistry; D046930:Thymus Plant / Q000737:chemistry
D056810:Acaricides; D009822:Oils, Volatile; D010938:Plant Oils
Acaricide effect; Beauveria bassiana; Combined treatment effect; Dermanyssus gallinae; Eucalyptus globulus