Aprimoramento da amostragem de grilos de serapilheira (Orthoptera: Gryllidae) por armadilha

Abstract

-Pitfall traps are used to sample litter inhabiting crickets, but some species are underestimated, because captured individuals escape from the trap. Here we suggest the substitution of aqueous detergent killing solution by formol-glicerin-alcohool solution, to increase sampling efficiency. We tested two hypotheses: (i) formol solution reduces the escape of crickets from the traps; (ii) formol solution is repellent. We arranged 80 traps in pairs of traps formol/detergent and detergent/detergent, 20 cm between traps within pairs, and 3 m between pairs. We collected 105 cricket individuals, being 29 adults, from nine species, in three taxonomic groups: Phalangopsinae, Trigonidiinae, and Brachytrupinae. Capture of both adults and nymphs was not affected by proximity of formol solution traps. In formoldetergent pairs, formol traps captured more adult individuals than detergent traps, but the number of nymphs did not differ. Therefore, formol was not repellent neither for adults nor nymphs. Traps with formol were more eficient, because they retained more adults than those with detergent, because of knock-down effect. Nymphs were not affected by the killing solution because their escape frequency is already low, due to their tiny size and reduced sclerotization. Tiny size implies short jumps, insuficient to escape. Reduced sclerotization implies greater permeability, so that once fallen into the trap, nymphs cannot escape any more.KEY WORDS: Methodology, inventary, ecology, locomotion behavior RESUMO -Amostram-se grilos de serapilheira com armadilhas enterradas (pitfall). No entanto, algumas espécies são sub-amostradas, por que alguns indivíduos conseguem fugir da armadilha. Neste trabalho sugerimos a substituição da solução aquosa de detergente, por uma solução de formol-glicerinaálcool, para aumentar a eficiência da amostragem. Testamos se: (i) formol reduz a fuga de grilos; (ii) formol é repelente para os grilos. Foram instaladas 80 armadilhas, formando pares formol-detergente e detergente-detergente, com 20 cm entre armadilhas dentro do par, e 3 m entre pares. Foram coletados 105 indivíduos, sendo 29 adultos, de nove espécies, em três grupos taxonômicos: Phalangopsinae, Trigonidiinae e Brachytrupinae. Tanto o número de adultos quanto de ninfas capturados nas armadilhas com detergente não foi afetado pela proximidade de armadilha com formol. Nos pares formol-detergente, o número de adultos em formol foi maior que em detergente, enquanto o número de ninfas não foi diferente. Assim, formol não foi repelente nem para adultos nem para ninfas de grilos. As armadilhas com formol foram mais eficientes, por reterem mais adultos do que as com detergente, devido ao efeito de knock-down. As ninfas não foram afetadas porque sua fuga do detergente já é reduzida, devido a seu tamanho reduzido e menor esclerotização. Tamanho menor implica saltos menores, insuficientes para o escape. Esclerotização menor implica maior permeabilidade, de forma que uma vez que a ninfa cai na armadilha, ela não consegue mais fugir.PALAVRAS-C...

Effects of Forest Regeneration on Crickets: Evaluating Environmental Drivers in a 300-Year Chronosequence

“…At each forest patch, at least 200 m from the patch border, we placed 10 sets of pitfall traps parallel to each other at 15 m intervals, with each set consisting of a line of 5 traps 1 m apart. Each pitfall trap contained a solution of 80% ethanol, 10% formaldehyde, and 10% glycerin as a killing and preservative agent, as recommended by Sperber et al [33]. The traps were maintained in the field for 48 hours, after which they were collected, and the crickets were [28].…”

Ocorrência do Grilo Endecous em Quatro Cavernas no Município de Uruará - PA, Brasil

“…São ainda utilizados para comportamento territorial e reprodutivo (bateman & FerGuson 2004) e também da ecologia (sPerber et al 2003;ribas et al 2005).…”

Preservation Methods Alter Carbon and Nitrogen Stable Isotope Values in Crickets (Orthoptera: Grylloidea)

“…Passive sampling techniques are used to solve this limitation, commonly via pitfall traps filled with killing solution [30, 33]. This and other passive sampling methods are essential for studies at large spatial and temporal scales, or in studies that test local environmental drivers of biodiversity (i.e., factors that influence biodiversity, such as soil moisture, vegetation structure, resource availability), and should minimize researcher interference.…”

“…Many types of killing solutions have been tested for efficiency in pitfall sampling, such as water and detergent [34], formaldehyde and ethylene glycol [33, 34], salt brines [35] and acetic acid [36]. However, ethanol solutions are considered as the most effective for cricket sampling due to rapid killing, which prevents escape [33, 37], and effective preservation of DNA [38, 39].…”

“…However, ethanol solutions are considered as the most effective for cricket sampling due to rapid killing, which prevents escape [33, 37], and effective preservation of DNA [38, 39]. Ethanol solutions are also the most common preservation method in cricket taxonomic collections (e.g.…”