Abstract
ABSTRACT One of the factors that may affect and limit the production in eucalypt plantations is the attack of defoliating insects. Among those, the brown eucalypt caterpillar, Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), stands out for being the major defoliating pest of Eucalyptus spp. in Brazil. Thus, the present study aimed to investigate the food consumption of T. arnobia, in its native host, guava (Psidium guajava L.), and in the different E. urograndis clones (VE 41, I 144, TP 361 and VCC 865). To assess T. arnobia food consumption, choice and non-choice tests were carried out using the native and the exotic host, alone or in combination. In non-choice tests, it was observed a higher consumption for the VE 41 clone and the native host (guava). The food consumption evaluation in choice tests indicated no food preference of T. arnobia between guava and E. urograndis clones, with the exception for the TP 361 clone, which was significantly less consumed than guava. In choice tests between the different E. urograndis clones, the clone I 144 presented a tendency towards lower food preference, being consumed only after 48 hours. In addition, the leaf consumption was similar between the VE 41, I1 14 e VCC 865 clones. In choice tests using the E. urograndis clones in pairs, the VE 41 clone was more consumed while the I 144 clone was less consumed when compared to the TP 361 clone. The obtained results provide basic information for the indication of eucalypt clones, and the understanding of the interaction and ecological relationships, assisting in the development of Forest Integrated Pest Management (Forest IPM) programs for the control of T. arnobia.
Highlights
For purposes of forestry genetic improvement, the genotypic features of each genetic material may directly affect the insect-plant interaction
It was found that all treatments were consumed, greater consumption of leaf area was observed for the native host guava, with an average leaf consumption area of 480.6 ± 89.52 mm2 and 841.1 ± 132.7 mm2, followed by the VE 41 clone with 455.6 ± 94.2 mm2 and 560.1 ± 108.5 mm2 after 24 and 48 hours, respectively, significantly differing from the other treatments (Figure 1)
The results obtained for the food consumption of T. arnobia on paired E. urograndis clones with guava (VE 41 x Guava; VCC 865 x Guava; I1 44 x Guava) showed similar consumption for the hosts, after 24h and 48h
Summary
For purposes of forestry genetic improvement, the genotypic features of each genetic material may directly affect the insect-plant interaction. Several management tactics are being developed to mitigate the yield losses caused by T. arnobia, including the selection of less susceptible species in the genus Eucalyptus, as well as the search for resistant genotypes or clones. According to Boiça Júnior et al (2013), plant resistance is a feature depending on environmental and genetic factors, and for that, different genetic materials, such as species, hybrids and/or clones of Eucalyptus spp. may show variations in susceptibility to biological agents, including defoliating insects, such as T. arnobia. Studies related to the interaction of native and exotic host species and the food consumption of T. arnobia, in the search for the characterization of non-preference resistance are still rare. Clone C10 (C. citriodora x C. torelliana), proved to be less preferred by T. arnobia, corroborating that T. arnobia exhibits a distinction between the genetic materials offered
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