International Union for the Study of Social Insects (IUSSI2018), August 5-10, 2018 in Guarujá, Brazil.

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COMPLEMENTARY DEFENSE MECHANISM IN THE TWO GUARD PHENOTYPES OF THE STINGLESS BEE TETRAGONISCA ANGUSTULA

Author(s):
Luana Leite Guimarães Santos, Luana Leite Guimarães Santos , Sidnei Mateus , Fábio Santos do Nascimento
Institution(s):
Programa de Pós-Graduação em Entomologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto/USP - Ribeirão Preto, SP - Brasil; Programa de Pós-Graduação em Entomologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto/USP - Ribeirão Preto, SP - Brasil ; Laboratório de Comportamento e Ecologia de Insetos Sociais, FFCLRP/USP, Ribeirão Preto, SP - Brasil ; Programa de Pós-Graduação em Entomologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto/USP - Ribeirão Preto, SP - Brasil
Tetragonisca angustula has aged- and morphological polyethism. Two types of guards are observed: hovering guards (HG-hover near the nest entrance) and stand guards (SG–stay fixed over the entrance tube). These two phenotypes seem to be complementary in colony defense, as they respond differently in some situations. This work investigated the proximal mechanisms that guards respond to distinct types of threat and modalities of approach. We evaluated the behavioral response of guards against N potential threat species, N non-aggressive species and a control group (filter paper with superglue). We used freshly anesthetized specimens, fixed to a flexible rod in tripod. The modalities of presentation were: placed on the substrate (Walking-W) 5 to 3 cm from the entrance tube, and diagonally to the entrance tube (Flying-F), 3 cm from the substrate. Wingless individuals were presented only in W. We made totally 366 trials. Both kind of guards were indifferent (~70%) toward control and Acromyrmex subterraneum. However, both modes of presentation with Scaptotrigona postica caused approach (F- HG 73% x W SG 33%) and attack (F and W- SG 21%) without recruitment. The responses to Trachypus boharti was moderately aggressive, while Lestrimelitta limao caused a longer and quicker aggressive response. To the non-aggressive ant Atta sexdens, there was agitation and approaches, this alarm response could be caused by citral isomers present in this threat. When offered a jumping spider, SGs moved to the opposite tube side (42%) and HG moved away from the entrance. In addition, SGs quickly entered the tube (36%) whit Camponotus ants. We concluded that the approach modality strongly influenced the decision of which group of guards attacked. Types of threats have promoted differential responses, aggressive or indifference. Our work also highlights the exclusivity of a more aggressive response toward L. limao, suggesting a selection directed to the defense against this cleptoparasite.
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