A comparison of insecticide susceptibility levels in 12 species of urban pest ants with special focus on the odorous house ant, Tapinoma sessile

Abstract

BACKGROUND Many ant species are pests in urban, agricultural, and natural habitats around the world. The primary means of reducing or eliminating ant infestations utilizes chemical control, mainly applications of residual insecticides. Control failures with residual insecticides are common, driven in part by a lack of understanding of basic biological and life history characteristics, including interspecific variation in susceptibility to insecticides. The current study evaluated the susceptibility of 12 species of urban pest ants to three classes of insecticides. RESULTS Results show significant variation in susceptibility across species. Contrary to the hypothesis of proportionality, no significant relationship was detected between body mass and median lethal time (LT50) or time to 100% mortality. The odorous house ant (Tapinoma sessile) was consistently the least susceptible to all insecticides, as indicated by the highest LT50 values and the greatest amount of time required to reach 100% mortality. Comparatively low susceptibility to commonly used spray insecticides may explain why T. sessile is such a persistent pest. Broadcast applications of spray insecticides may kill off the most susceptible species, leaving behind T. sessile. Lack of competition from other ant species, combined with increased access to nesting and feeding resources may allow T. sessile to fill a vacant ecological niche and expand its range. CONCLUSION Considering T. sessile's relatively low susceptibility to insecticides, its ability to become established in areas colonized by other invasive ants, and its highly invasive behaviors, it should be watched for by biosecurity programs as it has high potential to become a globally invasive pest. © 2021 Society of Chemical Industry.

Regional and caste‐specific variation in insecticide susceptibility in odorous house ants, Tapinoma sessile (Hymenoptera, Formicidae)

“…It is capable of long-distance jump-dispersal and becoming established in areas previously invaded by other invasive ants (Buczkowski and Krushelnycky, 2012). Additionally, T. sessile has low susceptibility to insecticides relative to other pest ants (Buczkowski, 2021). The ability of T. sessile to invade new habitats, form large supercolonies, display elevated insecticide tolerance relative to other ants, display elevated insecticide tolerance in queens relative to workers, and display significant variation in insecticide susceptibility across colonies make T. sessile a strong contender in global invasions.…”

“…Recently, a non-native, supercolonial population of T. sessile was discovered in Hawaii, demonstrating its potential global threat (Buczkowski and Krushelnycky, 2012). Among ants, T. sessile is infamous for being very hard to control (Buczkowski, 2021;Paysen, 2019). Tapinoma sessile consistently ranks as the #1 "call-back" ant among pest management professionals (Robbins, 2015).…”

“…Additionally, a recent study evaluated insecticide susceptibility in 12 species of urban pest ants, and T. sessile were consistently the least susceptible to all insecticides (Buczkowski, 2021). Comparatively, low susceptibility may be part of the reason why T. sessile is so persistent and so difficult to control.…”

“…Despite the tremendous economic and ecological impact of pest ants, effective management still faces many challenges and control failures with liquid spray insecticides are well‐documented in urban (Rust et al, 1996) and natural areas (Hoffmann et al, 2016; Silverman & Brightwell, 2008). The prevailing treatment strategies and product label rate determinations are not entirely compatible with the biology of many species (Buczkowski, 2021; Silverman & Brightwell, 2008) for several reasons; (1) cryptic nesting behaviours prohibit the direct treatment of colonies (Rust & Su, 2012), (2) colonies are typically very numerous which limits treatment performance and confounds monitoring effects (Hoffmann et al, 2011), (3) large‐scale treatments in natural areas with broad‐spectrum insecticides are problematic because of non‐target effects (Buczkowski & Wossler, 2019; Schläppi et al, 2021) and (4) there is large variation in susceptibility to insecticides across different ant species (Buczkowski, 2021).…”

“…Among ants, T . sessile is infamous for being very hard to control (Buczkowski, 2021; Paysen, 2019). Tapinoma sessile consistently ranks as the #1 “call‐back” ant among pest management professionals (Robbins, 2015).…”