<p>German cockroach (<i>Blattella
germanica</i> L.) is an important urban pest that poses health risks. They
carry pathogenic microorganisms, and the allergens present in their feces and
cast skins can trigger asthma attacks. Gel bait formulations containing
insecticides (indoxacarb and fipronil) have been used for German cockroach
control for more than a decade. However, historical data suggests that
cockroaches can develop resistance to insecticides that are repeatedly used.
Therefore, we investigated the status and inheritance patterns of fipronil and
indoxacarb resistance in cockroach strains collected from the state of Indiana
and Illinois. In the first objective, topical dose-response bioassays were
performed to determine fipronil and indoxacarb resistance levels in adult males
of three field strains (D-IL, I-IN, and S-IN) and the laboratory-susceptible
Orlando strain. Comparison of LD<sub>50</sub> (median lethal dose) values
between the susceptible and field strains revealed that resistance to both
insecticides in the D-IL and I-IN strains was <10-fold. However, fipronil
and indoxacarb resistance levels in the S-IN strain were 20- and
>10,000-fold, respectively. </p>
<p> </p>
<p>In the second objective, choice feeding bioassays were
performed to test the performance of the resistant S-IN strain (adult males) on
commercial fipronil and indoxacarb baits. Complete (100%) mortality of the S-IN
strain was observed on fipronil baits. However, average mortality on indoxacarb
baits was ~20% at 14d. In the third objective, synergist bioassays were done
with PBO and DEF to investigate the mechanism of indoxacarb resistance. PBO did
not significantly increase mortality in the S-IN strain at LD<sub>50</sub>, but
DEF did, suggesting increased hydrolase activity as a potential mechanism of
indoxacarb resistance. In the last objective, reciprocal crosses were performed
between the resistant S-IN strain and the susceptible Orlando strain to
determine patterns of insecticide resistance. Topical bioassays and associated
LD<sub>50</sub> values for the F1 generation adult males indicated that
fipronil resistance was inherited as an incompletely dominant trait with sex-linkage.
In contrast, indoxacarb resistance was inherited as a codominant trait and was
not sex-linked. Our results indicate that resistance can evolve independently
in different field strains. High-level indoxacarb resistance observed in the S-IN
strain warrants additional research on the indoxacarb target-site as a possible
resistance mechanism.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/7427708 |
| Date | 17 January 2019 |
| Creators | Ashari Zain (5930951) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Status_Inheritance_Pattern_and_Mechanism_of_Field-Evolved_Resistance_to_Gel_Bait_Insecticides_in_The_German_Cockroach/7427708 |
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