Chemical Control of Loxosceles intermedia (Araneae: Sicariidae) with Pyrethroids: Field and Laboratory Evaluation

• Published in: Journal of economic entomology Vol. 103; no. 1; pp. 166 - 171
• Main Authors: Navarro-Silva, M. A, Duque, J.E.L, Ramires, E. N, Andrade, C.F.S, Marques-Da-Silva, E, Marques, F. A, Delay, C. E, Fontana, J. D, Silva, A.C.S, Fraguas, G. M
• Format: Journal Article
• Language: English
• Published: Lanham, MD Entomological Society of America 01-02-2010
• Subjects: Animals; application rate; Arachnida; Araneae; arthropod pests; Biological and medical sciences; Blaberidae; Control; cypermethrin; deltamethrin; field experimentation; Fundamental and applied biological sciences. Psychology; Generalities; Insect Control; Insecticide Resistance; Insecticides - pharmacology; Invertebrates; lambda-cyhalothrin; lethal concentration 50; Loxosceles; Loxosceles intermedia; loxoscelism; MEDICAL ENTOMOLOGY; microencapsulation; mortality; pest control; pesticide resistance; Phoetalia circumvagans; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; public health; Pyrethrins - pharmacology; pyrethroid insecticides; pyrethroids; Sicariidae; spider bites; Spiders - drug effects; temporal variation; venoms; Brazil; Laboratory study; Evaluation; Loxosceles; Pyrethroids; Araneida; Arachnida; Pest management; Arthropoda; Chemical control; Sicariidae; loxoscelism; Invertebrata; pest control
• ISSN: 0022-0493; 1938-291X; 0022-0493
• DOI: 10.1603/EC09092

Bites from the recluse or brown spiders (genus Loxosceles) can cause necrotic lesions and systemic effects in humans throughout the world. In the state of Paraná, Brazil, loxoscelism is considered a serious public health problem, and Loxosceles intermedia Mello-Leitão (Araneae: Sicariidae) is associated with the majority of reported accidents. In the present research we evaluated the susceptibility of L. intermedia to pyrethroid insecticides currently used for the control of spiders in both field and laboratory conditions. In laboratory tests, the most active pesticides in descending order were microencapsulated lambda-cyhalothrin (LC50 = 0.023 mg/kg), nonmicroencapsulated lambda-cyhalothrin (LC50 = 0.047 mg/kg), deltamethrin (LC50 = 0.26 mg/kg), and Cypermethrin (LC50 = 1.38 mg/kg). Cockroaches, Phoetalia circumvagans (Burmeister) (n = 30), killed with microencapsulated lambdacyalothrin, were offered to the spiders. L. intermedia fed on 63.3% of the dead cockroaches during the first 6 h of experiment; none of the spiders died during the subsequent 15 d. Microencapsulated lambdacyalothrin was chosen for application in two contiguous houses. The mean volume applied was 22.8 mg (AI) /m2. Dead spiders were found during all the inspections up to 60 d after the initial application. In total, 297 dead spiders were collected; 65.7% in the attic shared by the two homes, 10.8% inside the house that had most cracks and crevices sealed and 23.6% in the control house. The use of lambda-cyhalothrin-based products for L. intermedia control is discussed.