Population dynamics of Cosmoclopius nigroannulatus Stal (Hemiptera, Reduviidae) in tobacco culture

Abstract

The role of predators influencing populations of insects considered as pests is extremely important for agroecosystems. The population ecology of Cosmoclopius nigroannulatus, a predatory reduvid associated with the tobacco culture was investigated aiming to study the population dynamics of adults, along the culture cycle. In an experimental plot of approximately 300 m 2 , in Porto Alegre (30°0'S; 51°13'W), RS, Brazil, 270 tobacco plants were grown; each plant identified by alphanumeric coordinates. Using the mark-release-recapture method, daily samplings were done from August to December 1999, and three times a week from this date until April 2000. The adults were captured by hand, marked, sexed and released on the same plant they were captured. The individual number and plant coordinate were registered. Population estimates were analyzed by the Fisher-Ford method. In 107 sampling occasions, 604 individuals were marked, 273 males and 331 females. Three generations of C. nigroannulatus were registered during the culture cycle. The colonizing generation was represented by 14 males and 15 females (a sex ratio of 0.48), the first by 109 males and 137 females (0.44) and the second by 150 males and 179 females (0.46). The estimated daily survival rate varied between generations decreasing from 98% in the colonizing generation to 87% in the second. The observed longevity or permanence time in the experimental area varied significantly among generations, being at about 40 days in the colonizing generation, 13 days in the first and 5 days in the second. It was observed that as the population increases, the survival and/or permanence time in the area decreases, suggesting a relation between this and a decline in the available resources probably with an associated increase in intra-specific competition.Key words: Cosmoclopius nigroannulatus, reduvids, predators, tobacco, natural enemies. RESUMO Dinâmica populacional de Cosmoclopius nigroannulatus Stal(Hemiptera, Reduviidae) em cultura de fumo A ação de predadores sobre populações de insetos considerados pragas é de suma importância em agroecossistemas. A ecologia populacional de Cosmoclopius nigroannulatus, um reduvídeo predador associado à cultura do fumo, foi investigada para estudar a dinâmica populacional dos adultos ao longo do ciclo da cultura. Numa área experimental (300 m 2 ), em Porto Alegre (30°01'S; 51°13'W), RS, Brasil, foram plantadas 270 mudas de fumo, identificadas por coordenadas alfanuméricas. As amostragens foram diárias de agosto a dezembro de 1999 e, a partir de então, três vezes por semana até abril de 2000. Os adultos foram capturados manualmente, marcados, sexados e devolvidos à mesma planta. Foram registrados o número, a coordenada e a localização na planta. Para análise das estimativas populacionais foi utilizado o método Fisher-Ford. Nas 107 ocasiões de amostragem, foram marcados 604 indivíduos, sendo 273 machos e 331 fêmeas. Foram registradas três gerações de C. nigroannulatus Braz. J. Biol., 62(4B) durante o ciclo da cultura. A geração c...

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

“…According to Jahnke et al (2002), C. nigroannulatus, the main predator in the system shows a dynamics highly synchronized with S. dentiventris, peaking during the second generation of the coreid, which corroborates the above suggestion. Nevertheless, the observed rise in mortality may also result from aggregation of these natural enemies in the plants where the coreids had remained for long stretches of time.…”

“…Casual observations in the field indicated the presence of the predator Cosmoclopius nigroannulatus Stål (Heteroptera: Reduviidae) in high numbers in the system. Population dynamics and the funcional response of this reduvid were the focuses of the works of Jahnke et al (2002) and Rocha (2002), respectively. This knowledge is adding to build a very detailed picture of the system, which will eventually allow a well fundamented theoretichal analysis.…”

Internal reproductive organs of Cosmoclopius nigroannulatus (Hemiptera: Reduviidae)

“…nymphs and adults feed mainly on nymphs of the tobacco grayish bug, Spartocera dentiventris berg (Hem. : coreidae) (Jahnke et al, 2002) and is an important mortality factor of the immature stages as well as teneral adults (caldas, 1998; canto-silva, 1999).…”

Molecular phylogeny of Harpactorinae and Bactrodinae uncovers complex evolution of sticky trap predation in assassin bugs (Heteroptera: Reduviidae)

“…Exogenous sticky trap predation occurs in several tribes of Harpactorinae and in Bactrodinae: species in the harpactorine tribes Apiomerini, Diaspidiini and Ectinoderini, the so‐called ‘resin bugs’ (Roepke, ; Usinger, ; Davis, ), cover their fore legs with plant resin, which enables them to more effectively hold on to struggling prey (Roepke, ; Miller, , ; Usinger, ; Forero et al., ). Certain Harpactorinae and all Bactrodinae appear to be preferentially associated with plants with sticky trichomes (Cobben and Wygodzinsky, ; Weirauch, ; Jahnke et al., ; Weirauch et al., ). Species in the genera Cosmoclopius and Pselliopus (Harpactorini) and Bactrodes (Bactrodinae) have been observed to scavenge on small insects (dead or alive) entrapped on these plants (Weirauch, ; Krimmel and Pearse, ; our unpublished data).…”