Interações entre o predador Podisus nigrispinus (Heteroptera: Pentatomidae) e o parasitóide Palmistichus elaeisis (Hymenoptera: Eulophidae) / Interactions among the predator Podisus nigrispinus (Heteroptera: Pentatomidae) and the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

10/09/2010

RESUMO

The use of more than one natural enemy for pests control can increase the efficiency of the biological control, mainly, when those organisms act on different apprenticeships of the pests. The diversification of the beneficial fauna can reduce the population of herbivores and the disturbance of the ecosystems, increasing the local stability. The objective was to determine the existence of competition and intraguild predation among Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) and immature of Palmistichus elaeisis Delvare &LaSalle (Hymenoptera: Eulophidae) and the effect of those phenomena in those natural enemies biology. In the chapter I Thyrinteina arnobia (Stoll) (Lepidoptera: Geometridae) and the host alternative Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) pupae were exposed to the parasitism for six females of P. elaeisis. To verify the selectivity of the predator a healthy pupa (T1) and another parasited by P. elaeisis (T2) were willing in opposite faces of Petri dishes. Podisus nigrispinus females were liberated, individually, in the center of those dishes and the preference of each female for pupae was observed. In the chapter II a hundred P. nigrispinus females were weighed and individualized in Petri dishes. Twenty-five of those females received for three consecutive days T. molitor healthy pupae (T1), while other 75 received pupae with one (T2) or nine (T3) or 18 days (T4) of the parasitism for P. elaeisis. The predation was allowed by 24 hours with the pupae being weighed before and after that period and substituted for a new. In the fourth day, the P. nigrispinus females were weighed again to evaluate the final weight of the same ones. In the chapter III pupae of the host alternative T. molitor were exposed to the parasitism for P. elaeisis for 24 hours. Those pupae containing P. elaeisis larvae or pupae were individualized in Petri dishes with a P. nigrispinus female. The treatments consisted of the no predation (T1) or 24 (T2) and 48 hours (T3) of the predator with the pupas. The pupas were removed of the Petri dishes and individualized in glass tubes. The cycle (egg-adult), the emergency, the longevity, the sexual reason and the morphometric parameters of P. elaeisis adults were appraised. In the chapters IV and V the treatments were P. nigrispinus nymphs fed with pupae of T. molitor parasited by P. elaeisis (T1); P. nigrispinus nymphs with parasited pupae or healthy in equivalent proportions (1:1) (T2) and P. nigrispinus nymphs with healthy pupae (T3). After the emergency P. nigrispinus adults received the same diet and they were put inside white sacks involving leaves of Eucalyptus spp. with a couple for sack. Podisus nigrispinus is selective, when avoiding parasited pupae and, when that doesn t happen, the intraguild predation happens in a symmetrical way. The consumption of the parasited preys biomass was smaller than the healthy ones and it increased with the progression of the parasitoid development. Podisus nigrispinus females reach the ideal weight (>60 mg) for larger fecundity same feeding of parasited preys. The intraguild predation affects the P. elaeisis emergency and biology. The number of adults emerged by pupa and the sexual reason of that parasitoid decreased when the host stayed with the predator for 48 hours. Host pupae with parasitoids in the larvae apprenticeship present positive effects in the biology, like as smaller cycle (egg-adult) and larger longevity of their females. Podisus nigrispinus can coexist with P. elaeisis and to have reduced impact in the acting of their nymphs for that competitor. Podisus nigrispinus nymphs in intense competition with P. elaeisis have your cycle increased in until eight days but predator survival stays high. The corporal mass of the nymphs and adults of P. nigrispinus were smaller with parasited pupae. The intense intraguild predation can also to reduce the oviposition and taxes of population growth and to increase the adults of P. nigrispinus mortality but without provoking the exclusion of the species. However, balanced competitions (1:1) with parasitoids have smaller impact in adults of that predator. The reduced impact of the competition or intraguild predation between P. nigrispinus and P. elaeisis shows that the predator cannot exclude P. elaeisis of the area or the reverse and those natural enemies possess coexistence strategies in the same habitat.

ASSUNTO(S)

predação intraguilda lepidoptera competição fitossanidade competition lepidoptera intraguild predation

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