Trail‐following behaviour and biological aspects of the gregarious caterpillar Brassolis sophorae (Lepidoptera: Nymphalidae)

Abstract

Brassolis sophorae (Linnaeus), the coconut palm caterpillar, is a pest in the Northeast region of Brazil. Despite its great importance, information about the biology and behaviour of this insect is scarce. B. sophorae caterpillars are gregarious, and they remain in a nest during the daytime and only come out at dusk to feed. When caterpillars leave the nest to forage, they lay down a trail of silk that leads the group to the feeding site. In spite of this, there is no scientific evidence showing whether trail-following behaviour in B. sophorae caterpillars is mediated by silk-associated chemical cues. This gregarious behaviour has probably hampered biological studies of this species. We determined biological parameters (number of instars and development time of each instar) of the larvae and conducted behavioural assays to assess whether trail-following behaviour of B. sophorae is mediated by chemical (silk extract) or physical (solvent-washed silk) cues, or a combination of both. Measurements of the head capsule width showed that B. sophorae larvae pass through six instars in an average period of 12 days per instar. Dual-choice tests in a Y-shaped arena showed that the larvae significantly preferred to walk on a silk-covered surface over a clean one and on a silk extract over hexane alone. When caterpillars were given the choice of walking on silk or on solvent-washed silk, they did not show a preference for either treatment. These results demonstrate the presence of pheromonal compounds in the silk of B. sophorae although the communication between caterpillars of B. sophorae is also mediated by physical cues. The results of this study broaden knowledge on the trail-following behaviour of immature larvae as well as the biology, morphology and behaviour of this insect.

Study of insecticide translocation in coconut palm trees after using pressurized endotherapy

“…These caterpillars stay in the nest during the day, and they come out to feed on the leaves at night. 5 The application of insecticides can represent a control option, but conventional techniques such as spraying do not solve this problem, especially for very tall coconut palm trees. Thus, vegetative endotherapy, as an alternative application technique of products applied directly to the stem, works by the impulse of xylemic translocation.…”

“…This phenomenon allows the products to reach the leaves through the water and mineral salt cycle in the photosynthesis process. 5,6…”

“…This phenomenon allows the products to reach the leaves through the water and mineral salt cycle in the photosynthesis process. 5,6 Although coconut has excellent nutritional benets, the intensive application of pesticides can lead to the development of pathogen resistance, in addition to leaving pesticide residues in food, which is a primary concern for producers and consumers. Pesticide residue analysis should be seen as a tool for monitoring residues in the nal product or throughout the production chain, aiming at disease control and food safety.…”

Interação da toxina Cry1Ac de Bacillus thuringiensis às BBMVs de diferentes ínstares de Chrysodeixis includens (Lepidoptera: Noctuidae)

“…Esse e um resultado de extrema importância para o início dos experimentos pois com essa informação foi determinada a idade correta das lagartas a serem utilizadas em bioensaios e na dissecação dos intestinos e para as avaliações relacionadas às BBMVs como o "Ligand Blotting" e os ensaios de competição. A distribuição de frequência da largura da cápsula cefálica tem sido comumente usada para identificar e estimar o número de ínstares larvares (WEITZNER; WHALON, 1987;CALVO;MOLINA, 2008;CASTAÑEDA-VILDÓZOLA et al, 2016;AMBROGI et al, 2016). O aumento dos ínstares ocorre em progressão geométrica em uma taxa constante (BORROR et al 1989).…”