Population fluctuation, immature mortality and adult longevity of Spartocera dentiventris (Berg) (Hemiptera: Coreidae) on Nicotiana tabacum (Solanaceae)

Abstract

Neotropical Entomology 32(3): 399-406 (2003) Flutuação Populacional, Mortalidade em Imaturos e Longevidade de Adultos de Spartocera dentiventris (Berg) (Hemiptera: Coreidae) em Nicotiana tabacum (Solanaceae) RESUMO imaturos foi estimada pela diferença entre os picos populacionais dos sucessivos ínstares em cada planta. O parasitismo foi avaliado com base na coloração dos ovos. Duas gerações desenvolveram-se ao longo do ciclo da cultura. As mortalidades para fases imaturas foram 93,6 ± 3,19% e 99,8 ± 0,20% para a primeira e segunda gerações, respectivamente. A mais alta taxa de mortalidade ocorreu em ninfas jovens e ovos. O parasitismo em ovos foi 8,9 ± 8,48% e 36,2 ± 3,63% para a primeira e segunda gerações, respectivamente. A razão sexual foi de 0,42 e a longevidade média dos adultos foi, no mínimo, 19,2 ± 1,00 dias, na primeira geração e 12,6 ± 2,52 dias, na segunda geração. O crescimento populacional de S. dentiventris foi drasticamente limitado por fatores de mortalidade; entre estes, os parasitóides Gryon gallardoi (Brethes) e Neorileya ashmeadi Crawford são responsáveis por parte das perdas em ovos e o reduvídio Cosmoclopius nigroannulatus Stål exerce aparentemente papel importante na predação de ninfas. PALAVRAS-CHAVE: Percevejo-cinzento-do-fumo, ecologia populacional, parasitismo ABSTRACT -The population fluctuations, mortality in the immature phases and longevity of the Spartocera dentiventris (Berg) adults were studied in an experimental plot of Nicotiana tabacum (Solanaceae) at the Faculdade de Agronomia -Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil (30 o 05' S and 51 o 13' W). From November 1996 to March 1997, 30 sampling occasions were carried out: 23 plants were inspected and the number of eggs and nymphs per instar counted and adults marked / recaptured. Mortality in immature bugs was estimated by the difference between the population peaks in successive instars per plants. Parasitism was evaluated based on the egg colour. Two generations developed through the cycle of the crop, the various instars overlapping in both generations. The mortality rates for immature phase were 93.6 ± 3.19% and 99.8 ± 0.20% for the first and second generations respectively. The highest rates of mortality occurred in young nymphs and eggs. Egg parasitization rates were 8.9 ± 8.48% and 36.2 ± 3.63% for the first and second generations respectively. Sex ratio was 0.42 and minimum average longevity for adults was 19.2 ± 1.00 days in the first and 12.6 ± 2.52 days in the second generation. Population growth was dramatically limited by mortality factors; amongst these, the parasitoids Gryon gallardoi (Brethes) and Neorileya ashmeadi Crawford account for much of the eggs losses and it is suggested that the reduvid Cosmoclopius nigroannulatus Stål plays an important role preying upon nymphs.

New and Revised Life History of the Florida HairstreakEumaeus atala(Lepidoptera: Lycaenidae) with Notes on its Current Conservation Status

“…Males lose scales more quickly than females as they do aerial displays to attract females. Hawkins 1995;Hawkins et al 1997;Queiroz 2002;Canto-Silva & Romanowski 2003).…”

Leaf-Footed Bugs (Coreidae)

“…Detailed information on the biology of this species is provided by Caldas et al ( 1998Caldas et al ( , 1999Caldas et al ( , 2000 including a description of the immatures, reproductive biology, longevity of adults, and cage studies of life history in tobacco. Mark-release-recapture in tobacco fi elds (Jesus et al 2002 ) documented the population dynamics of the bug over the tobacco growing season, showing an aggregated pattern of distribution and predation by the reduviid Cosmoclopius nigroannulatus Stål on the second generation of nymphs Canto-Silva & Romanowski ( 2003 ). This assassin bug shows a type II functional response when feeding on fi rst instar S. dentiventris (da Rocha and Redaelli 2004 ).…”