Boric acid, imidacloprid, and thiamethoxam in sucrose aqueous baits had different delayed toxicities to worker Argentine ants, Linepithema humile (Mayr). The concentrations required to produce an LT50 (time required to produce 50% mortality) within 1-4 d were 3.63-0.55% boric acid, 9.2 x 10(-3) to 7.1 x 10(-4)% imidacloprid, and 3 x 10(-4) to 2 x 10(-5)% thiamethoxam. The three toxicants were not repellent. Other laboratory trials showed that 1% boric acid, 5 x 10(-4) to 5 x 10(-3)% imidacloprid, and 1 x 10(-5) to 1 x 10(-3)% thiamethoxam had delayed toxic effects, whereas 0.5% boric acid and < 5 x 10(-3)% imidacloprid did not. Baits that provided an LT50 between days 1 and 4 were considered to have delayed toxic effects. The utility of aqueous sucrose baits and toxicants soluble in such systems and the negative impact of fast-acting toxicants on trail following, recruitment, trophallaxis, and control of Argentine ants are discussed.
Physicians in the United States should familiarize themselves with "kissing bugs" endemic to their area of practice and appreciate the medical implications of their bites. Bite victims often seek advice from physicians about allergic reactions as well as the risk of contracting Chagas disease. Physicians are generally knowledgeable about the role of kissing bugs in the transmission of Trypanosoma cruzi in Latin America. However, they may be unaware of (1) severe allergic reactions to kissing bug salivary antigens, (2) the widespread occurrence of T. cruzi amongst vertebrate hosts of kissing bugs, and (3) the incidence of T. cruzi among kissing bugs (T. cruzi may infect >50% of sampled bugs). Despite the potential for Chagas disease transmission, the major concern regarding kissing bugs in the United States is anaphylactic reactions to their bites resulting in frequent emergency department visits, especially in areas of endemicity in the Southwest.
A high proportion of triatomine insects, vectors for Trypanosoma cruzi trypanosomes, collected in Arizona and California and examined using a novel assay had fed on humans. Other triatomine insects were positive for T. cruzi parasite infection, which indicates that the potential exists for vector transmission of Chagas disease in the United States.
Clinicians should be aware that a common illness, infection with B. henselae, can be transmitted by arthropod vectors and a history of an animal scratch or bite is not necessary for disease transmission.
Control of Argentine ants, Linepithema humile (Mayr), around structures in urban settings requires an extensive and thorough use of existing registered sprays and baits. Barrier sprays must be thoroughly applied at maximum label rates to prevent ants from accessing structures. Although insecticides with systemic activity such as imidacloprid and thiamethoxam may ultimately reduce homopteran food sources for L. humile, quantifying the impact of such reductions has been difficult. Applications of bifenthrin and deltamethrin granules provide short-term reductions. Most commercial baits available for L. humile are not readily consumed by foragers, or they provide too rapid kill of workers. Consequently, none of the baits are consistently effective. Potential new active ingredients for baits such as fipronil, imidacloprid, and thiamethoxam provide about 50% kill within 3 days and are readily accepted by foragers. These toxicants are extremely promising in liquid bait formulations. No single control strategy or treatment has been consistently effective.
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