Mortality of the defoliator Euselasia eucerus (Lepidoptera: Riodinidae) by biotic factors in an Eucalyptus urophylla plantation in Minas Gerais State, Brazil

Euselasia eucerus (Hewitson, 1872) (Lepidoptera: Riodinidae) is a Brazilian native species commonly found in Eucalyptus plantations. Biotic mortality factors of this defoliator were studied in a Eucalyptus urophylla plantation in Minas Gerais State, Brazil aiming to identify natural enemies and their impact on this insect. Euselasia eucerus had biotic mortality factors during all development stages. The most important were Trichogramma maxacalii Voegelé and Pointel, 1980 (Hymenoptera: Trichogrammatidae) during egg stage (48.9 percent), a tachinid fly (Diptera: Tachinidae) during larval stages (10 percent) and Itoplectis sp. (Hymenoptera: Ichneumonidae) during pupal stage (52.2 percent). The parasitism rate was higher in the basal part of the plant canopy (37.8 percent).

Euselasia eucerus (Hewitson, 1872) (Lepidoptera: Riodinidae) é uma espécie brasileira nativa, comumente encontrada em plantios de Eucalyptus. Um estudo da mortalidade por fatores bióticos desse desfolhador foi feito em um plantio de Eucalyptus urophylla no Estado de Minas Gerais, Brasil, com o objetivo de identificar os inimigos naturais e seu impacto sobre esse lepidóptero. Euselasia eucerus possui fatores bióticos de mortalidade durante todas as suas fases de desenvolvimento. Os mais importantes foram Trichogramma maxacalii Voegelé e Pointel, 1980 (Hymenoptera: Trichogrammatidae) durante a fase de ovo (48,9 por cento), um Diptera: Tachinidae durante a fase de larva (10 por cento) e Itoplectis sp. (Hymenoptera: Ichneumonidae) durante a fase pupal (52,2 por cento). A taxa de parasitismo foi mais elevada na parte basal de plantas de eucalipto (37,8 por cento).

Main lepidopteran pest species from an eucalyptus plantation in Minas Gerais, Brazil

Lepidoptera species were monitored in a plantation of Eucalyptus grandis in the Municipality of Bom Despacho, State of Minas Gerais, Brazil from March 1987 to February 1992. A total of 547 species were collected and divided in: primary pests: 13; secondary pests: 20; species without defined importance to eucalyptus: 79; and non-identified species: 435. These four groups had a mean of 5231.29; 338.18; 438.16 and 2222.87 individuals with a total of 8229.87 individuals collected per trap. The number of species without defined importance to eucalyptus, and non-identified species, increased during the collecting period of five years while those of primary and secondary pests showed similar numbers in all years. The most collected primary pests Thyrinteina arnobia Stoll and Stenalcidia sp. (Geometridae) showed higher frequencies during the driest and coldest periods of the year, whereas Psorocampa denticulata Schaus (Notodontidae) was most frequent during periods of higher rainfall. Species of groups III and IV increased in diversity with eucalyptus age. This area has a high probability of outbreaks of eucalyptus defoliating caterpillars, especially T. arnobia. For this reason, lepidopteran pests should be monitored in this plantation during the driest and coldest periods of the year, when they can reach population peaks.

De marzo de 1987 a febrero de 1992 se realizó un monitoreo con trampas luminosas en plantaciones de Eucalyptus grandis en Bom Despacho, Minas Gerais, Brasil. Se recolectaron 547 especies del orden Lepidoptera: plagas primarias: 13; plagas secundarias: 20; especies sin importancia definida para el cultivo de eucalipto: 79; y especies no identificadas: 435. Estos cuatro grupos tuvieron medias de 5231.29; 338,18; 438.16 y 2222.87 individuos por trampa respectivamente, para un total de 8229.87 lepidopteros recolectados por trampa. Durante los cinco años hubo un aumento del número de especies de los grupos III y IV. Las plagas primarias con mayor número de individuos fueron Thyrinteina arnobia Stoll y Stenalcidia sp. (Geometridae), con las mayores frecuencias para los meses más secos y fríos del año. Psorocampa denticulata Schaus (Notodontidae) fue más abundante en los periodos más lluviosos. La probabilidad de brotes de larvas desfoliadoras de eucalipto, principalmente T. arnobia, es alta en la región. Se recomienda hacer el monitoreo de lepidópteros plaga en los periodos más secos y fríos del año, cuando pueden presentar picos poblacionales.

Fertility and life expectancy of the predator Supputius cincticeps (Heteroptera: Pentatomidae) exposed to sublethal doses of permethrin

The stinkbug Supputius cincticeps (Stål) (Heteroptera: Pentatomidae) can be found in agricultural and forest ecosystems feeding primarily on larvae of Coleoptera and Lepidoptera, where it can be exposed to insecticide applications. This study therefore aimed to evaluate the reproductive potential of'S. cincticeps after exposition to sublethal doses of permethrin (5.74 x 10-3, 5.74 x 10-2, 5.74 x 10-1, 5.74 and 57.44 ppb) through the use of a fertility life table. The development cycle of this predator was determined in order to calculate its net reproductive rate (R0), the infinitesimal (rm) and finite (λ) rates of increase in addition to mean generation time (T). The net reproductive (18.31), infinitesimal (rm) (0.050) and finite (λ) (1.051) rates of increase were higher, while generation time (57.93 days) was shorter for S. cincticeps exposed to 5.74x10-1 ppb of permethrin than in the control. This indicates a higher rate of population increase of this predator when exposed to this permethrin dose.