Selectivity of neem to Trichogramma pretiosum Riley and Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae)

Trichogramma pretiosum Riley and Trichogrammatoidea annulata De Santis are commonly found in avocado and persimmon orchards in northern Parana state. However, their abundance depends on whether insecticides are used or not to control the key lepidopteran pests Stenoma catenifer (Wals.) (Lepidoptera: Elachistidae) and Hypocala andremona (Stoll) (Lepidoptera: Noctuidae), respectively. The aim of this work was to evaluate the effects of an aqueous neem seed extract (ANSE) at 15, 3 and 1.5 percent, and of an emulsifiable concentrate neem oil (ECNO) at 2.5, 0.5 and 0.25 percent on lifetime parameters of these trichogrammatids as a way of testing the feasibility of integrating the biological and chemical control methods. Chemicals were applied on Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs before or after parasitization (one, three or five days). ANSE was more deleterious to both parasitoid species than ECNO, regardless of the concentration and the time of application. The chemicals acted on a concentration and time dependent manner. Treating the host with neem before parasitism was less deleterious to wasp emergence, especially for T. annulata. Pre-treatments (24h) of the host eggs with ECNO at concentrations varying from 0.5 percent to 0.25 percent did not affect T. pretiosum longevity, but 2.5 percent reduced T. annulata survival. Feeding wasps with honey mixed with 0.25 percent ECNO negatively affected T. annulata survival.

The adequacy of artificial oviposition substrates for laboratory rearing of Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae)

Studies in the laboratory tested the suitability of synthetic wool string, cotton string, cheesecloth, and commercial cotton ball as artificial oviposition substrates for the small green stink bug, Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae). In confined cages, 54 percent of total egg masses was laid on synthetic wool string, 31 percent on cotton string, and only 15 percent on cheesecloth. In an additional test, the best substrate selected, synthetic wool string, received 92 percent of egg masses compared to 8 percent on the commonly used substrate, cotton ball. Synthetic wool string received the most egg masses of any size, in particular those in the range 11-20 eggs/mass. Because the eggs of P. guildinii are laid in two parallel double rows, the egg masses fit the wool string perfectly.

Estudos foram conduzidos em laboratório para testar a adequabilidade de cordão de lã artificial, cordão de algodão, tecido voil e bola de algodão comercial como substrato artificial para oviposição do percevejo verde pequeno, Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae). Em gaiolas confinadas, 54 por cento do total de massas de ovos foi depositado sobre o cordão de lã artificial, 31 por cento sobre o cordão de algodão e apenas 15 por cento sobre o tecido voil. Em teste adicional, o melhor substato selecionado, cordão de lã artificial, recebeu 92 por cento das massas de ovos, comparado com 8 por cento das massas depositadas sobre o substrato comumente utilizado, bola de algodão. O cordão de lã artificial recebeu o maior número de massas de ovos de qualquer tamanho, em particular aquelas com 11-20 ovos/postura. A disposição das massas de ovos de P. guildinii, com os ovos depositados em duas filas paralelas, se encaixou perfeitamente no cordão de lã sintética.

Effect of neem seed oil aqueous solutions on survival and development of the predator Cycloneda sanguinea (L. ) (Coleoptera: Coccinellidae) / Efeito de soluções aquosas de óleo de sementes de nim, Azadirachta indica, na sobrevivência e desenvolvimento do predador Cycloneda sanguinea (L. ) (Coleoptera: Coccinellidae)

The effects of the neem seed oil aqueous solutions on survival and performance of egg, larva and adult stage of the Coccinelid predator Cycloneda sanguinea (L.) were evaluated under laboratory conditions. In a first trial, eggs and 2nd-instar larvae were sprayed with the neem solutions at 0; 0.5 and 2.25 ml/l and kept at 25 ± 1°C, 70 percent RH and 14h photoperiod. Egg viability and duration and larvae and pupae survival were evaluated as well as the predatory capacity of the larvae, adult longevity and reproduction. Egg spraying did not affect egg hatch or larvae survival and development. When the larvae were sprayed, significant mortality was observed only at the higher concentration (P < 0.05) and larval development and predatory capacity were not affected. Also, adults originated from treated larvae showed no alterations on sex rate, fecundity, fertility and longevity, thus indicating that at the tested concentrations the neem oil do not reduce the reproductive potential of the species. In a second experiment, adults collected in the field were sprayed with neem oil or kept on Parthenium sp. twigs sprayed with the neem oil aqueous solution at 5 ml/l, to evaluate survival. The neem oil at this concentration caused no mortality to the adults, since all of them, sprayed or kept on sprayed twigs, presented a longevity curve similar to untreated ones. The results indicate that the neem oil presents potential to be used in association with biological control of pests, when C. sanguinea is present.

Os efeitos de soluções aquosas do óleo de sementes de nim sobre o predador Cycloneda sanguinea (L.), nos estágios de ovo, larva e adulto, foram avaliados em laboratório. Em um primeiro experimento, ovos e larvas de 2° ínstar foram pulverizados com as soluções de nim nas concentrações de 0; 0, 5 e 2,25 ml/l de água apresentaram mortalidade significativa (P < 0,05) somente na maior concentração e o desenvolvimento larval e a capacidade predatória não foram afetados. Os adultos originados de larvas tratadas não apresentaram alterações da razão sexual, fecundidade, fertilidade e longevidade, indicando que nas concentrações testadas o óleo de nim não reduz o potencial reprodutivo da espécie. Em um segundo experimento, adultos da joaninha coletados no campo foram pulverizados com a solução aquosa de óleo de nim ou mantidos sobre ramos de losna-branca pulverizados na concentração de 5 ml/l de água, para avaliação da sobrevivência. A pulverização do óleo de nim nesta concentração não causou mortalidade nos adultos de C. sanguinea, uma vez que os insetos de ambos tratamentos apresentaram curva de longevidade semelhante à da testemunha. Os resultados demonstram que o nim apresenta potencial para ser utilizado em associação com o controle biológico de pragas, quando C. sanguinea for empregada.