Laboratory efficacy of mycoparasitic fungi (Aspergillus tubingensis and Trichoderma harzianum) against tropical bed bugs (Cimex hemipterus) (Hemiptera: Cimicidae)

ABSTRACT

Objective:To test the effectiveness of conidial spore formulations [Aspergillus tubingensis (A.tubingensis) and Trichoderma harzianum (T.harzianum)] against tropical bed bugs,Clnex hemipterus.Methods:Spore formulations were made from two fungal strains,T.harzianum and A.tubingensis.The bed bugs were exposed to the conidial spores placed soaked onto a fabric cloth for 1 h and the mortality counts were recorded daily until 14 days.Results:Mean survival times based on Kaplan-Meier survival analysis showed no significant differences between all the concentrations in both the fungal isolates:T.harzianum and A.tubingensis.However,the evaluation of both the isolates in terms of virulence resulted in low lethal hours in all the concentrations except for the high concentration ofA.tubingensis (LT50 =44.629 h) at the conidial exposure of 1 × 106 spores/mL.Rapid mortality of the bed bugs was observed from Day 6 to Day 12,ranging from 13％ to 90％ in all three concentrations of A.tubingensis.With reference to the T.harzianum exposure,the concentration of 1 × 104 spores/mL displayed a gradual increase in the percentage mortality of 90 on Day 14.Conclusions:Approaches to the bed bugs treatment should be explored in-depth using a natural biological agent like fungus especially A.tubingensis to reduce this pest population,in order to replace chemical methods.