Susceptibility of nymphs and adults of Blattella germanica (Dictyoptera: Blattellidae) to Aspergillus terreus (Eurotiales: Trichocomaceae) infested via oral ingestion, contact, and bait methods: a comparative study [Erratum: May 2022, v.57(2); p.147-149]
2022
Djouhri, Yamina | Saidi-Touati, Mahdia | Benelmouffok, Amina | Bouchtout, Mohamed Nadji
Blattella germanica Linnaeus (Dictyoptera: Blattellidae) is a household pest that transmits pathogens to humans. Aspergillus terreus Thom (Eurotiales: Trichocomaceae) is an entomopathogenic fungi potentially useful in biological control. The present paper evaluates the susceptibility of nymphs and adults of B. germanica to A. terreus. Two concentrations of fungi spores (1 × 10⁶ and 1 × 10⁸ spores/mL) were administered to cockroaches through different routes (ingestion, direct contact and bait) and mortality was monitored for 15 days. Ingestion of A. terreus spores at concentration 1 × 10⁶ spores/mL showed mortalities of 16.67% on nymphs and 71.48% on adults. With the higher concentration, mortality reached 37.78% on nymphs and 82.22% on adults. Treatment by direct contact with 1 × 10⁶ spores/mL resulted in mortalities of 27.41% and 71.48% on nymphs and adults, respectively, whereas the infestation with 1 × 10⁸ spores/ml yielded greater mortality rates (38.15% in nymphs and 92.96% in adults). Baits had insignificant effects on B. germanica. In conclusion, our study showed the existence of a lethal effect of A. terreus spores on B. germanica and that the observed effect varies depending on the insect developmental stage, the administered concentration, and the mode of contamination, with a maximum effect recorded in adults infested with 1 × 10⁸ spores/mL via direct contact.
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