No abstract

A well known case of ineffective natural biological control: the puzzling coexistence of the coffee leaf miner, Leucoptera coffeellum (Guérin-Mèneville), and its natural enemies was analyzed. Despite being a suitable prey to eight parasitoid species and three wasp species, all occurring simultaneously, the coffee leaf miner too often presents populations far above the damaging level for the coffee plantation. It is demonstrated that predatory wasps and parasitoids interact negatively, possibly because predatory wasps kill parasitized miner's larvae. In doing so, predatory wasps indirectly kill parasitoids, thereby impairing the efficacy of the natural biological control. It is warned that biological control programs should be based on knowledge of food web interactions, rather than simply on strategies involving introduction of exotic natural enemies.

The objective of this research was to develop a methodology to describe the movement of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae) in the field through: (i) the evaluation of allele variation of a microsatellite marker on polymorphic Colombian H. hampei populations; (ii) the invention of a device for releasing H. hampei adults; (iii) the standardization of a release-recapture technique for H. hampei populations; (iv) the estimation of the flight distance of the insect; and (v) the calculation of a mathematical expression that describes the movement of H. hampei in space over time. The results indicated that: (i) the microsatellite molecular marker HHK.1.6 was exclusively present in a population from Guapotá-Santander, was dominant and allows the evaluation of H. hampei movement for several generations; (ii) a device that released 88.8% of H. hampei adults in 2 s was designed; (iii) this device was used as H. hampei populations containing HHK.1.6 marker release strategy, and coffee seeds as recapture strategy; (iv) it was estimated that H. hampei adults flew as far as 65 m, however, 90% were recovered in a radius of <40 m. Finally, (v) the mathematical expression that described the movement of H. hampei in space over time was Y^=αβXi, being Y^ the average number of borer beetles recaptured per tree, and x the distance in meters. This method will allow to determine the movement of H. hampei from different environmental and ecological scenarios.

No abstract

The first representative of the genus Mastotermes Froggatt, 1897 from the Cenozoic of the South America is described here based on seven specimens from the Fonseca Formation, Eocene-Oligocene boundary, Minas Gerais State, southeastern Brazil. Today, Mastotermes is geographically restricted to northern Australia, with only one relict species, Mastotermes darwiniensis Froggatt, 1897. However, its fossil record clearly shows a global distribution, with species ranging from the Cretaceous of Myanmar, Russia, Mongolia and China, throughout Cenozoic of mainland Europe and Miocene of Africa, Mesoamerica and the Caribbean. Along with Spagotermes costalimai Emerson, 1965, Mastotermes brasiliensis sp. n. is the second fossil termite recorded in the Fonseca strata. This discovery extends the paleo-distribution of this genus into Neotropical South America during the Paleogene.

Studies were performed to evaluate the suitability of a commercial gouache as an external marker for termite workers in lab assays. Dyed and non-dyed termites presented similar survival for the first 300 minutes since the experiment has began, and differed after this time. Mortality did not differ for termites dyed in two different colours from the same brand of gouache. It was concluded that commercial gouache could be a suitable marker for Cornitermes cumulans (Isoptera: Termitidae) termites, provided following restrictions were applied (i) tested hypotheses did not rely on times to death greater than 300 min., or (ii) experiments included "sham-dyed" termites (i. e., a "control" group with "dyed" individuals, rather than the tradicional control group composed by non-dyed individuals).

The study of self-propelled particles is a fast growing research topic where biological inspired movement is increasingly becoming of much interest. A relevant example is the collective motion of social insects, whose variety and complexity offer fertile grounds for theoretical abstractions. It has been demonstrated that the collective motion involved in the searching behaviour of termites is consistent with self-similarity, anomalous diffusion and Lévy walks. In this work we use visibility graphs –a method that maps time series into graphs and quantifies the signal complexity via graph topological metrics– in the context of social insects foraging trajectories extracted from experiments. Our analysis indicates that the patterns observed for isolated termites change qualitatively when the termite density is increased, and such change cannot be explained by jamming effects only, pointing to collective effects emerging due to non-trivial foraging interactions between insects as the cause. Moreover, we find that such onset of complexity is maximised for intermediate termite densities.