Germano Leão Demolin Leite

Immunity of an Alternative Host Can Be Overcome by Higher Densities of Its Parasitoids Palmistichus elaeisis and Trichospilus diatraeae

Interactions of the parasitoids Palmistichus elaeisis Delvare & LaSalle and Trichospilus diatraeae Cherian & Margabandhu (Hymenoptera: Eulophidae) with its alternative host Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae) affect the success or failure of the mass production of these parasitoids for use in integrated pest management programs. The aim of this study was to evaluate changes in the cellular defense and encapsulation ability of A. gemmatalis pupae against P. elaeisis or T. diatraeae in adult parasitoid densities of 1, 3, 5, 7, 9, 11 or 13 parasitoids/pupae. We evaluated the total quantity of circulating hemocytes and the encapsulation rate versus density. Increasing parasitoid density reduced the total number of hemocytes in the hemolymph and the encapsulation rate by parasitized pupae. Furthermore, densities of P. elaeisis above 5 parasitoids/pupae caused higher reduction in total hemocyte numbers. The encapsulation rate fell with increasing parasitoid density. However, parasitic invasion by both species induced generally similar responses. The reduction in defensive capacity of A. gemmatalis is related to the adjustment of the density of these parasitoids to their development in this host. Thus, the role of the density of P. elaeisis or T. diatraeae by pupa is induced suppression of cellular defense and encapsulation of the host, even without them possesses a co-evolutionary history. Furthermore, these findings can predict the success of P. elaeisis and T. diatraeae in the control of insect pests through the use of immunology as a tool for evaluation of natural enemies.

Note: Flight capacity, parasitism and emergence of fiveTrichogramma (Hymenoptera: Trichogrammatidae) species from forest areas in Brazil

The flight and parasitism capacities and emergence rate of fiveTrichogramma species [T. acacioi (Brun),T. bruni (Nagaraja),T. demoraesi (Nagaraja),T. maxacalii (Voegelé & Pointel) andT. soaresi (Nagaraja)] were compared. The flight capacity of these parasitoids was assessed in test units. A tube was placed inside each test unit with a piece of card with 300Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs parasitized by one of theTrichogramma species. The emerged adults inside the test units were classified according to their position as flyers, non-flyers and walkers. Cards withA. kuehniella eggs, parasitized by one of theTrichogramma species, were assessed to determine the parasitism rate and emergence of these natural enemies. The data were submitted to analysis of variance and the means compared by the Scott-Knott test at 5% probability.Trichogramma maxacalii exhibited better flight capacity than the other species, in addition to good parasitism rate and high percentage of emergence.

Within tree distribution of a gall-inducing Eurytoma (Hymenoptera, Eurytomidae) on Caryocar brasiliense (Caryocaraceae)

For the first time, we identified the insect herbivore that induces one of the most conspicuous galls on the leaves of Caryocar brasiliense Camb. (Caryocaraceae), a widespread, typical cerrado woody plant of large economic importance. The gall inducing organism is a new and undescribed species of Eurytoma sp. (Hymenoptera, Eurytomidae). Furthermore, we recorded its spatial distribution within C. brasiliense trees. More Eurytoma galls were found on the eastern tree slope, followed the southern and northern slopes. More galls were found in the interior of the tree crown, i.e., on the proximal portion of the stems compared to the terminal portion. At the leaf level, more galls were found on the median region compared to the distal or proximal, perhaps due to the lower trichome density found in there. Leaf colonization by Eurytoma sp. may initiate at the leaf margin but after colonization reaches 50% the central portion starts to be colonized.

Factors affecting mite herbivory on eggplants in Brazil.

The objective of this study was to determine effects of total rainfall, mean temperature, predators, height of canopy, levels of nitrogen and potassium in leaves, and the density of leaf trichomes on the attack intensity of Tetranychus evansi and T. urticae (Acari: Tetranychidae) and Aculops lycopersici (Acari: Eriophyidae) in five plantations of the eggplant Solanum melongena var. ‘Natu Nobilis’ in two regions of Brazil. Higher numbers of individuals of A. lycopersici, T. evansi and T. urticae/cm2 were observed on eggplants in the Municipality of Guidoval than in Viçosa which might be explained by the fact that Guidoval showed hotter and more rainy weather. A. lycopersici was positively correlated with mean temperature (r = 0.54, P = 0.03), and T. evansi was positively correlated with total rainfall (r = 0.54; P = 0.04), while for T. urticae the correlation with total rainfall was almost significant (r = 0.47, P = 0.055). No significant effects were found (P > 0.05) of natural enemies, levels of N and K and leaf trichome density on population densities of mites. A. lycopersici showed higher density on the apical leaves while nymphs and adults of T. evansi and eggs of T. urticae had higher numbers on leaves of the apical and medium parts of eggplants than on the lower leaves. Nymphs and adults of T. urticae showed higher attack intensity on leaves from the medium and lower thirds of the plants.

Seletividade de inseticidas a Polybia ignobilis (Haliday) (Hymenoptera: Vespidae) predador de Ascia monuste orseis (Godart) (Lepidoptera: Pieridae)

The selectivity of carbaryl, deltamethrin, methyl parathion, permethrin and thrichlorfon to the predator Polybia ignobilis (Haliday) was evaluated in dosages which killed 90% of 4th and 5th instars of Ascia monuste orseis (Godart). Methyl parathion (86% average mortality) and carbaryl (62%) were not selective to P. ignobilis; thrichlorfon and permethrin (4%) were more selective while deltamethrin showed intermediate selectivity (26% average mortality). Adults of P. ignobilis with yellow strips (38%) were more tolerant to carbaryl than those without this characteristic (86% average mortality).

Rice-straw mulch reduces the green peach aphid, Myzus persicae (Hemiptera: Aphididae) populations on kale, Brassica oleracea var. acephala (Brassicaceae) plants.

Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21–36°C and to 18–32°C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30°C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.

Does Thyrinteina arnobia (Lepidoptera: Geometridae) use different defense behaviours against predators?

The efficiency of biological control programs with predators depends on knowing defense behaviour of caterpillars to avoid or to reduce predation. The objective was to evaluate whether caterpillars of Thyrinteina arnobia (Lepidoptera: Geometridae) associate different defense behaviours against the predator Podisus distinctus (Heteroptera: Pentatomidae) and to describe them. Adults of this predator were released in three wood screen cages (50 cm × 40 cm × 40 cm) and maintained without food for two days. Caterpillars of T. arnobia of different instars were released inside each cage. Behaviour patterns of these caterpillars were evaluated during 6 consecutive hours. The caterpillars, initially, explored the environment and they assumed camouflage position. They attacked the predators with the jaws. A new defense behaviour was observed in 43% of T. arno bia caterpillars. They hung from silk threads in the cage when upset by the predators. Caterpillars of this herbivore presented different defense behaviour including camouflage, attacking the predator with its jaws and hung from silk threads. This last one is the most efficient defense behaviour against the predator P. distinctus.ZusammenfassungDie Effizienz biologischer Bekämpfungsprogramme mittels Räubern beruht auf der Kenntnis der Verteidigungsstrategien der Schaderreger zur Vermeidung oder Verminderung der Prä-dation. Das Ziel dieser Studie war die Untersuchung der Frage, ob Larven der Schmetterlingsart Thyrinteina arnobia (Lepido-ptera: Geometridae) unterschiedliche Abwehrstrategien ge-genüber der räuberischen Wanze Podisus distinctus (Heterop-tera: Pentatomidae) verwenden und, falls dies zuträfe, sie zu beschreiben. Adulte Exemplare der Raubwanze wurden zu diesem Zweck in drei Holzrahmenkäfige der Ma ß e 50 cm × 40 cm × 40 cm zwei Tage ohne Futter gehalten. Dann wurden Larven unterschiedlicher Entwicklungsstadien von T. A r nob ia in die Käfige gesetzt. Das Verhalten dieser Larven wurde wäh-rend der folgenden 6 Stunden beobachtet. Zu Beginn erkunde-ten die Schmetterlingslarven die Umgebung und nahmen dann eine Tarnhaltung ein. Während Angriffen der Raubwanzen attackierten sie die Räuber mit Hilfe ihrer Mandibeln. Ein bis-lang nicht bekanntes Abwehrverhalten bestand darin, dass 43% der angegriffenen Tiere ihren Aufenthaltsort mit Hilfe von Spinnfäden verlie ß en. Dieses Abwehrverhalten ist effizienter als die Tarnung und der Angriff der Raubwanze P. distin ctus.

Factors affecting colonization and abundance of Aphis gossypii glover (hemiptera: aphididae) on okra plantations

O controle de Aphis gossypii Glover (Hemiptera: Aphididae) em quiabeiro Abelmoschus esculentus (L.) (Malvaceae) consiste principalmente no uso de inseticidas, em virtude da falta de informacao sobre outros fatores de mortalidade. Objetivou-se com este estudo determinar os efeitos de predadores e parasitoides, altura de dossel, idade da planta, area foliar, compostos orgânicos foliares, niveis de nitrogenio e potassio, densidade de tricomas, pluviosidade e temperatura na intensidade de ataque de A. gossypii em dois cultivos sucessivos de Abelmoschus esculentus var. Santa Cruz. Estimou-se, mensalmente, o numero de A. gossypii e de inimigos naturais (inspecao visual) ocorridos nas folhas (uma folha/planta) localizadas nas partes basal, mediana e apical de 30 plantas/plantacao. Os fatores que mais contribuiram com a reducao da populacao de pulgoes foram a senescencia de plantas, area foliar e inimigos naturais, principalmente Adialytus spp., aranhas e Coccinellidae. Maior numero de pulgoes foi observado na parte basal que na mediana e apical de plantas de quiabeiro. A pluviosidade total pode reduzir a populacao de pulgoes. Tricomas tectores (nao-glandulares) ou baixa densidade destes, compostos orgânicos foliares e niveis de N e de K nao foram importantes para a reducao da populacao de pulgoes.

Selectivity of insecticides to predators of aphids

Estudou-se a seletividade dos inseticidas cipermetrina, diclorvos, diazinon, etion, fenitrotion, malation, metamidofos, paration metilico, permetrina, pirimicarbe e vamidation para adultos dos predadores Cycloneda sanguinea (L.) e Eriopis connexa (Germ.)(Coleoptera: Coccinellidae). Folhas de tomateiro foram imersas em caldas inseticidas nas doses utilizadas para o controle dos pulgoes Myzus persicae (Sulzer) e Macrosiphum euphorbiae (Thomas) em tomateiro e tambem na metade das doses recomendadas. Os fatores em estudo foram os inseticidas, as doses, as especies de predadores e o sexo para C. sanguinea. Vamidation e o pirimicarbe foram os inseticidas mais seletivos a C. sanguinea seguidos do etion e diclorvos (3,2; 6,7; 49,7 e 52,5% de mortalidade, respectivamente). Para E. connexa o pirimicarbe foi o mais seletivo seguido pelo etion e cipermetrina (1,96; 71,28 e 81,92% de mortalidade, respectivamente). Os machos de C. sanguinea foram mais tolerantes que as femeas ao etion (33 e 66,5% de mortalidade) e permetrina (61 e 100% de mortalidade, respectivamente). A toxicidade da permetrina a E. connexa e do etion as femeas de C. sanguinea foi menor quando estes inseticidas foram aplicados em subdose (74,4 e 25% de mortalidade, respectivamente) do que quando estes foram aplicados na dose recomendada (100 e 66,5% de mortalidade, respectivamente) para o controle de pulgoes no tomateiro.

Efeito do AIB sobre a qualidade e fitossanidade dos alporques de influência da Caryocar brasiliense Camb (caryocaraceae)

The aim of this study was to test the influence of indol butiric acid (IBA) at four levels (0, 500, 1000, and 2000 ppm) to obtain healthy air layering of Caryocar brasiliense Camb (Caryocaraceae). In addition, we also observed the direct effect of this hormone on the success of leaf gall induction by Eurytoma sp. (Hymenoptera: Eurytomidae), and its indirect effect on galling insect parasitoids. A complete randomized design was used, with three replicates of each plot containing two air layering, and five treatments: 1) no girdling, 2) girdled + 0ppm IBA; 3) girdled + 500ppm IBA; 4) girdled + 1000ppm IBA, 5) girdled + 2000ppm IBA. The rates of air layering rooting, root/air layering, largest root length/air layering, callus formation and girdled shoots survival were not influenced by the different concentrations of IBA (p> 0.05). Furthermore, the number of the parasitoid Quadrastichus sp. (Hymenoptera: Eulophidae) and external morphological traits of the gall induced by Eurytoma sp. were not influenced by the different treatments. However, a positive relationship was found between IBA concentration and galls successfully induced, and between the number of adults of the galling Eurytoma sp. and its major parasitoid, Sycophila sp. (Hymenoptera: Eurytomidae) with 2.000ppm of IBA. These data indicate that the galling insect may select plant modules or plants with higher hormone concentration and that IBA may play a role in gall induction. Due to the low success of this hormone in the asexual propagation of C. brasiliense more studies are needed as this plant is one of the most important species in the Brazilian woodland savanna biome. Further studies are also needed to address hormone role in gall formation and its indirect effect on the community of associated parasitoids.