Laboratory efficacy of mycoparasitic fungi (Aspergillus tubingensis and Trichoderma harzianum) against tropical bed bugs (Cimex hemipterus) (Hemiptera: Cimicidae)
Objective: To test the effectiveness of conidial spore formulations [Aspergillus tubin- gensis (A. tubingensis) and Trichoderma harzianum (T. harzianum)] against tropical bed bugs, Cimex 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 con- centration of A. tubingensis (LT 50 = 44.629 h) at the conidial exposure of 1 × 10 6 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 × 10 4 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.
Supported by Universiti Sains Malaysia (Grant No. 304/PBIOLOGI/6313030).