Morphology of immature stages, biological parameters and life table of Microtechnites bractatus (Hemiptera: Miridae) on different host plants

ABSTRACT The garden fleahopper, Microtechnites bractatus (Say) (Hemiptera: Miridae), is associated with several cultivated plant species and, despite its economic importance, little is known about its development and performance in such hosts. We described here, the morphology of immature stages, and evaluated the biology of M. bractatus in beans, potatoes, white clover, alfalfa, and wheat. The bioassays were carried out in the laboratory under controlled temperature (25±2ºC), humidity (UR70±15%), and photoperiod (12L:12D). The eggs of M. bractatus are elongated and slightly curved, without respiratory projections and light yellow in color, becoming dark at the end of the incubation period. Nymphs present an oval-shaped body, a reddish color that intensifies along with the development and dimorphic wing pads in the fifth instar. In the bioassays, the host plants influenced the biological aspects of M. bractatus, both in the immature and adult stages. Nymph survival was higher in clover and alfalfa, while in wheat, it was lower. Clover-fed insects had the longest longevity. The fecundity parameters and egg viability were favored in insects that fed on clover and alfalfa. The fertility life table showed that feeding M. bractatus with clover provides a higher net reproduction rate (R0) and a higher finite ratio of population increase (ʎ). This study contributes to bioecological and behavioral studies on M. bractatus and provides data for the recognition and characterization of individuals in the immature stage.

Integrative taxonomy and phylogeography of Telenomus remus (Scelionidae), with the first record of natural parasitism of Spodoptera spp. in Brazil.

The egg parasitoid Telenomus remus (Hymenoptera: Scelionidae) has been investigated for classical and applied biological control of noctuid pests, especially Spodoptera (Lepidoptera: Noctuidae) species. Although T. remus was introduced into Brazil over three decades ago for classical biological control of S. frugiperda, this wasp has not been recorded as established in corn or soybean crops. We used an integrative approach to identify T. remus, combining a taxonomic key based on the male genitalia with DNA barcoding, using a cytochrome c oxidase subunit I mitochondrial gene fragment. This is the first report of natural parasitism of T. remus on S. frugiperda and S. cosmioides eggs at two locations in Brazil. We also confirmed that the T. remus lineage in Brazil derives from a strain in Venezuela (originally from Papua New Guinea and introduced into the Americas, Africa, and Asia). The occurrence of T. remus parasitizing S. frugiperda and S. cosmioides eggs in field conditions, not associated with inundative releases, suggests that the species has managed to establish itself in the field in Brazil. This opens possibilities for future biological control programs, since T. remus shows good potential for mass rearing and egg parasitism of important agricultural pests such as Spodoptera species.

Ação sistêmica e translaminar do óleo de nim visando ao controle de Tuta absoluta (Meyrick) (Lep: Gelechiidae) em tomateiro / Systemic and translaminar action of neem oil for the control of Tuta absoluta (Meyrick) (Lep: Gelechiidae) in tomato

A traça Tuta absoluta (Meyrick) é o inseto-praga que mais compromete a produção do tomateiro. Basear o seu controle no uso de inseticidas sintéticos pode comprometer a cultura em termos econômicos e ambientais. Como alternativa de controle, o óleo de nim foi aplicado em folhas de tomateiro, avaliando os efeitos inseticida e antialimentar por ação sistêmica e translaminar. No ensaio para avaliar a ação translaminar, o óleo diluído em água foi aplicado na superfície adaxial dos folíolos, em concentrações de 0,5, 1, 5 e 10%. A mortalidade observada variou entre 49 e 100%, e o tamanho médio das minas, entre 1,62 e 0,34 cm. Nos tratamentos representados por água e água + emulsificante (5%), a mortalidade não ultrapassou 20%, com tamanho médio das minas de 1,63 cm. O estudo da ação sistêmica foi realizado ao aplicar o óleo de nim na superfície adaxial e abaxial de todas as folhas das plantas, à exceção daquelas em que as lagartas foram infestadas. Neste ensaio, o óleo foi aplicado nas concentrações de 1, 2,5 e 5%, diluídos em água e emulsificante. Observou-se que a mortalidade foi maior que 90% quando o óleo foi aplicado nas concentrações de 2,5 e 5%, sendo o tamanho médio das minas inferior a 1,0 cm. Não ocorreu mortalidade nos tratamentos controle, mas o tamanho das minas foi, em média, de 1,96 cm. Desta maneira ficou evidenciado que o óleo de nim apresenta efeito inseticida e antialimentar sobre lagartas de T. absoluta, com a propriedade de ser incorporado e translocado através das folhas de tomateiro.(AU)

The leaf miner Tuta absoluta (Meyrick) is the pest that mostly jeopardizes tomato production. The use of synthetic pesticides for its control can affect the crop economically and environmentally. As an alternative form of control, neem oil was applied on tomato leaves in order to assess antifeedant and insecticidal effects by systemic and translaminar action. In experiment for translaminar action, oil diluted in water was applied to the adaxial surface of leaflets at concentrations of 0.5, 1, 5 and 10%. The mortality rate ranged between 49 and 100%, and the average size of the mines, between 1.62 and 0.34 cm. In treatments represented by water and water + emulsifier (5%), mortality did not surpass 20%, with the average size of mines reaching 1.63 cm. The study of systemic action was performed by applying neem oil to the adaxial and abaxial surfaces of all leaves, except those that were infested by caterpillars. In this assay, the oil was applied at concentrations of 1, 2.5 and 5%, being diluted in water and emulsifiers. We observed that the mortality rate exceeded 90% when the oil was applied at concentrations of 2.5 and 5%, and the average size of mines was smaller than 1.0 cm. There was no mortality in the control treatments, but the mine size was on average 1.96 cm. Therefore, it is clear that the neem oil has an insecticidal and anti-food effect on T. absoluta caterpillars, and is possible to be incorporated and applied on tomato leaves.(AU)

Effect of carbon dioxide (CO2) on mortality and reproduction of Anagasta kuehniella (Zeller 1879), in mass rearing, aiming at the production of Trichogramma spp.

Eggs of Anagasta kuehniella (Zeller 1879) are widely used for mass rearing of Trichogramma spp. and other parasitoids and predators, largely commercialized in many countries. The aim of this study is to evaluate the effect of carbon dioxide (CO2) originated from larval metabolism on the biological parameters of A. kuehniella. For that purpose, we assess the production of carbon dioxide (CO2) per rearing tray of A. kuehniella and the effect of CO2 on the viability of egg-to-adult period and oviposition of A. kuehniella. Results allow to estimate that a rearing tray, containing 10,000 larvae between the 4th and 5th instars, produces an average of 30.67 mL of CO2 per hour. The highest egg production of A. kuehniella was obtained when the larvae were kept in rooms with lower concentration of CO2 (1,200 parts per million - ppm), producing 23% more eggs than in rooms with higher CO2 concentrations. In rooms with high density of trays (70 trays/room), CO2 concentration exceeded 4,400 ppm. The viability of the egg-to-adult period was not influenced by carbon dioxide.