Can Bacillus thuringiensis affect the biological variables of natural enemies of Lepidoptera? / Bacillus thuringiensis pode afetar as variáveis biológicas de inimigos naturais de Lepidoptera?

The entomopathogen Bacillus thuringiensis (Bt) is widely used as one of the ingredients in pest control formulations, but researches conducted on its effect on non-target organisms are still in the nascent stage. This investigation aimed to uncover if Bt treated with Tenebrio molitor (Coleoptera: Tenebrionidae) larvae and pupae could affect the biological variables of Podisus nigrispinus (Hemiptera: Pentatomidae) and Palmistichus elaeisis (Hymenoptera: Eulophidae), all of which established natural enemies of leaf defoliator caterpillars in the eucalyptus culture. Larvae of T. molitor were fed on wheat bran containing different concentrations of B. thuringiensis (0.00; 0.25; 0.50; 1.00; 2.00 and 4.00 g Agree/kg bran). When the larvae attained size of about 2 cm, they were used as prey for P. nigrispinus (Bioassay I), and their pupae used as hosts for P. elaeisis (Bioassay II). Only the biological variables oviposition period and egg numbers by posture of the predator P. nigrispinus were altered. The biological variables of P. elaeisis were not altered, since it was possible to use these control methods within the integrated pest management.(AU)

O entomopatógeno Bacillus thuringiensis é amplamente empregado no controle de pragas, porém estudos de seu efeito sobre organismos não alvo ainda são incipientes. Com isso, objetivou-se neste trabalho avaliar se larvas de Tenebrio molitor (Coleoptera: Tenebrionidae), tratadas com Bacillus thuringiensis, podem afetar as variáveis biológicas de Podisus nigrispinus (Hemiptera: Pentatomidae) e Palmistichus elaeisis (Hymenoptera: Eulophidae), importantes inimigos naturais de lagartas desfolhadoras na cultura do eucalipto. Larvas de T. molitor foram alimentadas com farelo de trigo contendo diferentes concentrações de Bacillus thuringiensis (0,00; 0,25; 0,50; 1,00; 2,00 e 4,00 g de Agree®/kg farelo). Quando as larvas atingiram em média 2 cm de comprimento, foram usadas como presa para P. nigrispinus (bioensaio I) e as pupas como hospedeiro para P. elaeisis (bioensaio II). As variáveis biológicas período de oviposição e número de ovos por postura do predador P. nigrispinus foram alteradas. Já as variáveis biológicas de P. elaeisis não foram modificadas, sendo possível o uso conjunto desses métodos de controle no manejo integrado de pragas.(AU)

New records of natural enemies of Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Pernambuco, Brazil

We report the occurrence of natural enemies of Plutella xylostela (L.) in organically farmed kale in Pernambuco, Brazil. Seven natural enemies were observed parasitizing or preying on larvae and pupae of P. xylostella - three parasitoids: Cotesia plutellae Kurdjumov (Hym.: Braconidae), Conura pseudofulvovariegata (Becker) (Hym.: Chalcididae) and Tetrastichus howardi (Olliff) (Hym.: Eulophidae), and four predators: Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), Pheidole sp.Westwood (Hym.: Formicidae), nymphs and adults of Podisus nigrispinus (Dallas) (Hem.: Pentatomidae), and one unidentified species of solitary wasp. Beyond recording these natural enemies, data on predation of P. xylostella larvae in the field and laboratory by C. inclusum are presented.