Lampetis instabilis, (LAPORTE AND GORY)

Lemes, Pedro Guilherme, Anjos, Norivaldos Dos & Cedeño, Pedro Emílio, 2013, Outbreak of Lampetis instabilis (Laporte and Gory) (Coleoptera: Buprestidae) on Regrowth Plantation ofEucalyptus urophylla S. T. Blake × Eucalyptus grandis Hill Ex Maiden Hybrids in Brazil, The Coleopterists Bulletin 67 (4), pp. 566-568 : 566-567

OUTBREAK OF LAMPETIS INSTABILIS (LAPORTE AND GORY) ( COLEOPTERA : BUPRESTIDAE ) ON REGROWTH PLANTATION OF EUCALYPTUS UROPHYLLA S. T. BLAKE × EUCALYPTUS GRANDIS HILL EX MAIDEN HYBRIDS IN BRAZIL

PEDRO GUILHERME LEMES, NORIVALDOS DOS ANJOS, AND PEDRO EMÍLIO CEDEÑO Laboratory of Integrated Management of Defoliator Beetles Department of Entomology, Av. P.H. Rolfs, s/n, Centro, Universidade Federal de Viçosa Viçosa, Minas Gerais, BRAZIL [e-mail]

The area of cultivated eucalyptus in Brazil reached 5,102,030 ha in 2012, of which 28.2% is located in Minas Gerais, the largest producer in the country. The expansion of areas planted with eucalyptus is a result of a range of factors that favor large-scale planting of this genus, such as the fast-growing, short rotation cycles and high productivity ( ABRAF 2013). The need for supplying raw materials for industries leads to the need for expanding monocultures, and eventually leads to the emergence of insect pests at high levels ( Schowalter et al. 1986).

Defoliator beetles are an important group of pests for forestry because they cause damage to plants in the seedling stage, in nurseries, and mature trees in the plantation. Among eucalyptus defoliator beetles in the plant’ s native range, the most important are those belonging to the families Curculionidae , Scarabaeidae , and Chrysomelidae (Ohmart and Edwards 1991) . In Brazil, beetles of the families Cerambycidae , Chrysomelidae , Curculionidae , Scarabaeidae , and Buprestidae are among the main pests that attack this crop (Anjos and Majer 2003; Garlet et al. 2011). Buprestids in the genera Psiloptera Dejean, 1833 and Lampetis Dejean, 1833 have been reported to cause damage in eucalyptus plantations in Brazil ( Silva et al. 1968; Anjos and Majer 2003; De Nadai et al. 2012).

Species of Lampetis are important defoliators in new plantings, occurring mainly in areas planted in a minimum tillage system. Injury is caused by the adults chewing the stems, which, when done on the apical branch, can lead to loss of apical dominance, to stagnation of growth, and to reduced height ( Zanuncio et al. 1993; Anjos and Majer 2003). Given that these beetles can cause significant problems in eucalyptus plantations, our objective is to report the occurrence of an outbreak in a plantation located in the municipality of Grão Mogol, state of Minas Gerais, Brazil.

Sampling was conducted in December 2010 in a regrowth area of Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden hybrids felled about two months earlier. There were other regrowth stands and cut and stored logs drying around the study area. One sampling was made in order to evaluate and calculate the incidence and severity of the injuries. One hundred eucalyptus stumps were randomly examined from the edge to the center of the plantation, and the number of shoots per stump and number of Lampetis beetles present on each stump were recorded. The severity of damage was evaluated on a scale of 0 to 5 (0 = no injury, 1 = lateral branches injured, 3 = main and lateral branches partially injured, and 5 = main and lateral branches totally injured). Overall incidence was calculated by dividing the number of beetles by the number of shoots.

Adult buprestids were collected as they fed and injured eucalyptus stems. They were then taken to the Laboratory of Forest Pest Management (DDE/CCB/UFV) in Viçosa, Minas Gerais, Brazil, where they were pinned, labeled, and identified based on comparisons with specimens in the Regional Museum of Entomology (UFVB).

The jewel beetle that was damaging the eucalyptus shoots was identified as Lampetis instabilis (Laporte and Gory) ( Fig. 1A ), and was present in an area of approximately 1,000 ha. The outbreak began in the first half of December 2010, which coincided with the rainy season, the period of greatest emergence of various beetles in this region.

Adult L. instabilis feed by chewing down the tender shoots on both the main and side branches ( Fig. 1B ); they also feed on the leaves and bark. The average number of shoots per stump was 7.2, whereas the average number of beetles per stump was 0.1, resulting in an incidence of about 1.8 beetles per 100 shoots. The average severity of damage was 0.85. We found no correlation between the number of beetles per plant and the number of shoots per stump. However, we observed that tender shoots, with an apparent high amount of anthocyanin, were not attacked. Foliar anthocyanin may be related to plant resistance to herbivory (Coley and Kursar 1996). There is a correlation between insect herbivory and foliar anthocyanin level in Eucalyptus saligna Smith and Eucalyptus paniculata Smith ( Stone et al. 2001). The feeding preference of the leaf-cutting ant Atta columbica ( Hymenoptera : Formicidae ) decreased with increased anthocyanin level in leaves of species on which they usually forage (Coley and Aide 1989). Anthocyanins levels may also provide a visual cue to herbivores of levels of other phytochemicals (Close and Beadle 2003).

Damage and injuries reported here are consistent with those reported for Lampetis nigerrima (Kerremans) and Ectinogonia buquetti (Spinola) feeding on eucalyptus (Anjos and Majer 2003; Valdebenito et al. 2009). Although there are native plants resprouting between the rows in eucalyptus plantations, no injuries or feeding on them were detected.

A similar attack by L. nigerrima on threemonth-old E. urophylla × E. grandis hybrids caused a loss of approximately 7.77% of the wood volume, compared to trees without attack, when the trees completed 32 months of growth ( De Nadai et al. 2012). Moreover, an attack by this insect caused deformities that detracted from the quality of the stem, causing difficulties in harvesting the wood and in transportation. These deformations and bifurcations can also negatively affect the commercial value of timber ( Shepherd 1994).

The damage severity value is below the economic injury level recommended by De Nadai (2005) to control L. nigerrima , indicating that, in this case, there was no need to control L. instabilis . The average severity of damage value of 0.85 represents an intermediate situation between “no injuries” and “lateral branches injured”. Due to the level of incidence of L. instabilis , intervention was not justifiable. This highlights the importance of adopting a model of proper monitoring that takes into account the number of shoots per stump and not merely the number of stumps.

If the recommendation was to combat this type of beetle, the most appropriate control technique would be manual picking. Anjos and Majer (2003) recommended manual picking of L. nigerrima beetles in an area of 1,243 ha of eucalyptus plantation. These species of jewel beetles have poor flying skills, which facilitate the use of this technique to control them ( De Nadai 2005).

Thus, we registered the occurrence of L. instabilis at outbreak population levels with neither sufficient incidence nor severity to require curative intervention, but highlighting the possibility of this jewel beetle to become one more economically important defoliating pest of eucalyptus in Brazil.

Figures

Fig. 1. Lampetis instabilis and injury to the main (A) and side (B) branches of Eucalyptus urophylla × E. grandis shoots, Grão Mogol, Minas Gerais, Brazil.