Recent studies have shown an insecticidal effect of Tithonia diversifolia (Hemsl.) Gray (Asterales: Asteraceae) foliage on workers of Atta cephalotes L. and inhibitory effects of this plant on the growth of the symbiotic fungus Leucoagaricus gongylophorus (A. Müler) Singer. To evaluate the potential of T. diversifolia as a biological control treatment of this important pest, we assessed the effect of green manure (mulch) of this plant on natural nests of A. cephalotes, in Cali, Colombia. Three treatments were randomly assigned to 30 nests: 1) green mulch of T. diversifolia, 2) green mulch of Miconia sp., Ruiz & Pav. and 3) unmulched control. Every 2 wk for 6 mo, the surface of the nests was completely covered with leaves. Physical and chemical parameters of nest soil were assessed before the first and after the last application of the mulch. Ant foraging in T. diversifolia-treated nests decreased by 60% after the initial applications of the mulch, while nest surface area decreased by 40%. When the nests covered with T. diversifolia were opened, it was observed that the superficial fungus chambers had been relocated at a greater depth. In addition, microbial activity and soil pH increased by 84% and 12%, respectively, in nests covered with plant residues. In conclusion, the continued use of T. diversifolia mulch reduces foraging activity and negatively affects the internal conditions of the colonies, thereby inducing the ants to relocate the fungus chambers within the nests.
The genus Attaphila, comprising minute myrmecophilous cockroaches, is revised, including now six previously known (A. aptera, A. bergi, A. flava, A. fungicola, A. schuppi, A. sexdentis) and three new species (A. multisetosasp. nov. Bohn and Klass, A. paucisetosasp. nov. Bohn and Klass, A. sinuosocarinatasp. nov. Bohn and Klass). All species are described or redescribed and depicted with their main characteristics; determination keys allow the identification of males and females. Especially the male characters allow a distribution to two species-groups with differing host specificity: bergi-group associated with Acromyrmex (and possibly Amoimyrmex) ants, fungicola-group associated with Atta ants; the former appears paraphyletic, the latter monophyletic. The genus Attaphila is characterised emphasising its unique features: (1) insertion of antennae at the bottom of a wide funnel-shaped deepening; (2) antenna with the possibility of a rectangular bending between scapus and pedicellus (associated with a distal excavation of the scapus) and (3) with an unusual shape and low number of antennomeres; (4) femora of legs with a ventral groove allowing a close spacing of femur and tibia during a strong flexion; (5) a complex and unusual shape of the laterosternal shelf area of the female genitalia (lack of shelf, presence of a pair of complicated tubular invaginations); and (6) lateral parts of abdominal tergite T9 of male ending in a pair of ventromesally directed arms, which contact the lateral margins of the subgenital plate. Functional aspects and the possible biological roles of these features are discussed. Older biological data are summarised and new observations are presented. The position of Attaphila within Blattodea is discussed. Like a recent molecular study, the morphology of the male genitalia places the genus in the Blaberoidea. The molecular result of Attaphila being closest to three particular blattellid genera, however, is conflictual from the morphological perspective.
Leaf-cutter ants are agricultural and urban pests that defy chemical control methods. Laboratory and field studies have revealed repellent and insecticidal activity by the extracts of Tithonia diversifolia (Asteraceae), known as Mexican sunflower, as a promising alternative for the control of the leaf-cutter ant Atta cephalotes. This study evaluated the effects of different extracts (non-polar and polar) of T. diversifolia dry leaves on worker ants from laboratory colonies of A. cephalotes through ingestion and contact. In addition, the biological activity of the extracts as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was evaluated. A dichloromethane extract at 1000 ppm presented the highest insecticidal activity through ingestion, causing 70% and 90% worker ant mortality after five and seven days of treatment, respectively. The acetylcholinesterase inhibition values showed that the dichloromethane presented the best AChE concentration of inhibition (IC50) at 73.9 ± 11.06 μg/mL, compared to its fractions, which demonstrates that its activity is potentiated when the crude extract is used. Our results can be attributed to the existence of terpenes and sesquiterpene lactones, which are likely inhibitors of AChE, in T. diversifolia.
Adoption of a surrogate artificial queen in a colony of Atta cephalotes (L.) (Hymenoptera: Formicidae) in Colombia The colonies of Atta cephalotes (L.) are monogynous: i.e. has a single queen, fed and protected by thousands of workers. It is estimated that a queen lives for 15 years and is irreplaceable, that is, when it dies, the colony disappears (Hölldobler & Wilson, 2011). The workers, especially the soldiers, are territorial and defend the colony from the presence and or attack of intruders, even those of the same species (Whitehouse & Jaffe, 1995). In the same way, the workers reject winged queens from other colonies that approach their territory. They are attacked, and in most cases, dismembered (C. Giraldo, Foundation Center for Research on Sustainable Farming Systems (CIPAV) personal communication, August 21, 2013). At present, it is unknown whether the foundation of nests of A. cephalotes with more than one queen occurs, or if A. cephalotes workers have the ability to adopt new queens into their nest without altering the work within the colony and/or affecting the surrogate queen. Recently, the queen of a colony of A. cephalotes with eight years of establishment under
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.