Abstract
To use Palmistichus elaeisis Delvare and LaSalle, 1993 (Hymenoptera: Eulophidae) in a biological control programme of Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), it is necessary to study thermal requirements, because temperature can affect the metabolism and bioecological aspects. The objective was to determine the thermal requirements and estimate the number of generations of P. elaeisis in different Eucalyptus plantations regions. After 24 hours in contact with the parasitoid, the pupae was placed in 16, 19, 22, 25, 28 and 31 °C, 70 ± 10% of relative humidity and 14 hours of photophase. The duration of the life cycle of P. elaeisis was reduced with the increase in the temperature. At 31 °C the parasitoid could not finish the cycle in T. arnobia pupae. The emergence of P. elaeisis was not affected by the temperature, except at 31 °C. The number of individuals was between six and 1238 per pupae, being higher at 16 °C. The thermal threshold of development (Tb) and the thermal constant (K) of this parasitoid were 3.92 °C and 478.85 degree-days (GD), respectively, allowing for the completion of 14.98 generations per year in Linhares, Espírito Santo State, 13.87 in Pompéu and 11.75 in Viçosa, Minas Gerais State and 14.10 in Dourados, Mato Grosso do Sul State.
Highlights
The lepidopterous defoliators species are dangerous and harmful pests, presenting frequent outbreaks and damage to the eucalyptus forest (Zanuncio et al, 2009)
Laboratory establishment of T. arnobia. Eggs of this species were obtained at the Laboratory of Biological Control of Insects and the Animal Biology Department of the Federal University of Viçosa (UFV), Minas Gerais state and after hatching, larvae of Lepidoptera were placed in bags of organza fabric (0.70 × 0.40 cm), involving branches of eucalyptus plants and removed to other branches, every three days
The progeny of P. elaeisis by T. arnobia pupae ranged from six to 1238 individuals being higher at 16 °C (R2 = 0.7991, F = 4.1979, p = 0.0085; gl = 75)
Summary
The lepidopterous defoliators species are dangerous and harmful pests, presenting frequent outbreaks and damage to the eucalyptus forest (Zanuncio et al, 2009). Anjos et al (1987) record that in field surveys, it was found that the total defoliation of eucalyptus trees by T. arnobia reduced the average volume of wood in 60% and caused 6% of tree mortality. The parasitoids are natural enemies of major importance for the stability balance of the eucalyptus agroecosystem. These parasitoid assemblages are characterised by their high diversity and potential in the biological control of lepidopterous defoliators (Oliveira et al, 2003; Pereira et al, 2008)
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