Maurício Ursi Ventura

Antifeedant activity of Melia azedarach (L.) extracts to Diabrotica speciosa (Genn.)(Coleoptera: Chrysomelidae) beetles

Studies were carried out to determine the antifeedant activity of extracts of leaves, stems, flowers and fruits of Melia azedarach (L.), the dosage activity responses to the most active extract and the effects of sunlight in the activity persistence to Diabrotica speciosa (Genn.) beetles. Extracts efficiency was determined by evaluating leaf consumption. Insect feeding was deterred by stems, fruits and flowers extracts. Flowers and fruits extracts were the most efficient. Stems extract was in an intermediate position between the two most efficient and the least one (leaf extracts). The most active extract (flowers) was sprayed at concentrations of 0, 1, 2, 3, 4, 5, 6 and 7 g/100 ml. Feeding of D. speciosa on common bean leaves extracts decreased significantly with increasing concentrations of flowers extract, responding in a concentration-dependent manner. Two days after spraying, from 4 to 7 g/100 ml concentrations, feeding was totally inhibited. Four days after spraying, feeding occurred in 4-g/100 ml concentration. When common bean plants exposed to sunlight were sprayed with flowers extract (5-g/100 ml), beetles feeding increased gradually after extract spraying. Results showed that the lack of activity under sunlight conditions was a great limitation to use M. azedarach aqueous extracts.

Capture of hypothenemus hampei ferrari (coleoptera, scolytidae) in response to trap characteristics

Armadilhas iscadas com semioquimicos tem sido propostas para manejo da broca-do-cafe. O cafeeiro e cultivado em condicoes ambientais diversas que podem afetar a eficiencia das armadilhas. Varios modelos de armadilha e variacoes nos modelos sao utilizados. Uma serie de experimentos de campo objetivou avaliar capturas da broca-do-cafe em armadilhas numa lavoura de cafe semi-adensado no Norte do Parana. Uma garrafa plastica (2 L) com uma abertura (13 × 18 cm) constituiu a armadilha. O etanol (E), metanol (M) e oleo de cafe, sozinhos, nao incrementaram as capturas quando se utilizaram armadilhas transparentes com um frasco difusor com furo de 2 mm; armadilhas iscadas com as misturas 1 : 1, 1 : 2 e 1 : 3 de etanol (E) + metanol (M) capturaram quantidades similares e superiores a testemunha; sinergismo ocorreu pela mistura de etanol e metanol; a adicao do oleo de cafe as misturas nao incrementou as capturas. Armadilhas com taxas de liberacao da mistura E:M (1:1) de 342, 400, 428 e 710 mg dia -1 capturaram quantidades similares. Armadilhas verdes transparentes, transparentes e vermelhas, iscadas com E:M (1:1) (642 mg dia-1) capturaram quantidades similares. Foi observada interacao entre as cores (verde transparente, transparente, vermelha) e taxas de liberacao dos semioquimicos (540, 720 e 1100 mg dia-1). Armadilhas verdes transparentes, quando iscadas com doses de 720 mg dia-1 da mistura 1:1 de E:M, capturaram 2,3 e 4,4 mais insetos do que 540 e 1100 mg dia-1; e capturaram 3,2 mais insetos do que armadilhas transparentes e vermelhas.

Morphology of olfactory sensilla and its role in host plant recognition by Neomegalotomus parvus (Westwood) (Heteroptera: Alydidae)

ABSTRACT The external morphology of the sensilla, including pores and permeable points on the cuticle of the antennae ofadults of Neomegalotomus parvus (West.) (Heteroptera: Alydidae) was investigated with regard to their olfactoryfunction. Behavioural evidence of olfaction, the importance of the different antennal segments in locating the hostunder still-air, and the responses of the insects to plants´ scents and to pheromones in wind assays were alsostudied. With the scanning electronic microscope mechanoreceptor sensilla were found on the four segments of theantennae of N. parvus. The density of the sensilla was greater on the 4 th segment. On the apical segment, sensillawith olfactory morphological traits were observed. Bugs with intact antennae located food more frequently andfaster than those with blocked or amputated antennae. N. parvus preferred intact seeds to sealed seeds, but therewas no preference when the last segment of the antenna was blocked. In wind tunnel, bugs were attracted to matureand green pods, and to hexanic extract of mature pods of pigeon pea, Cajanus cajan (L.) Millsp.; there was noresponse to panicles of rice, Oryza sativa L. or to the male pheromone.Key words: Sensilla, host plant, behaviour, antenna

Population Dynamics of Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae) on Host Plants

The stink bug Dichelops melacanthus (Dallas) has become one of the major pests of corn and wheat in Brasil, mainly after a shift from the conventional tillage system to the no tillage cultivation system. This fact may be due to the simultaneous occurrence of second planting corn with wheat cultivation, and the presence of wild hosts. This study aimed to evaluate the population dynamics of D. melacanthus on wild hosts adjacent to areas cultivated with corn, wheat, and soybean during the season and off-season of soybean cultivation. Weekly surveys were conducted in the region of Londrina, PR, Brasil from the beginning of July 2007 up to the end of June 2008 using the square meter method. Corn (Zea mays), soybean (Glycine max), tropical spiderwort (Commelina benghalensis), hairy indigo (Indigofera hirsuta), crotalaria (Crotalaria pallida), wheat (Triticum aestivum), and signal grass (Brachiaria decumbens) were identified as hosts of D. melacanthus. Signal grass was the host in which stink bug adults were found in higher numbers, while nymphs and adults were consistently collected on tropical spiderwort. Although nymphs completed their development on tropical spiderwort seeds, this host was found less suitable than soybean seeds.

Identification of defensive compounds in metathoracic glands of adults of the stink bug Dichelops melacanthus (Hemiptera: Pentatomidae)

Os conteudos das glândulas metatoracicas de insetos adultos do percevejo Dichelops melacanthus (Hemiptera: Pentatomidae) foram analisados. Os compostos de defesa foram identificados combinando as tecnicas de cromatografia gasosa (CG), cromatografia gasosa acoplada a espectrometria de massas (CG-EM) e por comparacao de seus indices de retencao com os de compostos padroes. Tridecano foi o componente majoritario, seguido de quantidades menores e aproximadamente iguais de (E)-4-oxo-2-hexenal e (E)-2-octenal. Tambem foram identificados (E)-2-hexenal, decano, acetato de (E)-2-hexenila, undecano, (E)-4-oxo-2-octenal, dodecano, acetato de (E)-2-octenila, 1-trideceno, tetradecano e pentadecano. The contents of metathoracic glands of adults of the stink bug Dichelops melacanthus (Hemiptera: Pentatomidae) were analyzed. Compounds were identified by gas chromatography (GC), coupled GC-mass spectrometry and matching retention indices and mass spectra with those of authentic samples. Tridecane was the major component followed by lesser and approximately equal amounts of (E)-4-oxo-2-hexenal and (E)-2-octenal. Other compounds identified include (E)-2-hexenal, decane, (E)-2-hexenyl acetate, undecane, (E)-4-oxo-2-octenal, dodecane, (E)-2-octenyl acetate, 1-tridecene, tetradecane and pentadecane.

Population dynamics, gregarious behavior and oviposition preference of Neomegalotomus parvus (Westwood) (Hemiptera: Heteroptera: Alydidae)

Interactions between Neomegalotomus parvus (Westwood) (Coreoidea: Heteroptera: Alydidae) and host plants were investigated including population monitoring throughout the year, gregarious behavior in the field, and oviposition preference among host plants and one non-host plant in field cages. Cowpea, Vigna unguiculata (L.) Walp., soybean, Glycine max (L.) Mill. cv. BR 37, pigeon pea, Cajanus cajan (L.) Mill., pigeon pea cv. Anao, and lablab, Dolichos lablab L. were monitored in the field. N. parvus was found on host plants during 11 months. The shortest period of occurrence was observed on soybean and the longest on lablab. Insects were found mostly on mature pods. Contagious distribution (negative bionomial) was detected, characterizing the aggregation. Greater number of eggs were observed on pigeon pea, followed by soybean and lablab. Eggs were not found on cowpea, on common bean Phaseolus vulgaris L., and on rice, Oryza sativa L.

Males Are Attracted by Female Traps: A New Perspective for Management of Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) Using Sexual Pheromone

The field responses of Diabrotica speciosa (Germar) to traps baited with adults were studied as an suggestion of the pheromone production. Firstly, an assay to settle a suitable height placement to capture D. speciosa was carried out in common beans, Phaseolus vulgaris L., field. Traps placed at 0.25-m height captured ca. 3.5 times more beetles than 0.5, 0.75 and 1.0-m traps. The responses to virgin females and males of two ages (younger = 24 to 72h and older = 72 to 120h after adult emergence), mated females and males were assessed in common bean interplanted among coffee, Coffea arabica L., field. Virgin females baited traps captured ca. 22 times (younger) and 13 times (older females) more male beetles than control traps. Captures were ca. 70% more effective using younger females. None of the other treatments improved trap attraction. These results strongly indicated that there is a female-produced sexual pheromone in D. speciosa.

Resistance of Maize Landraces to the Maize Weevil Sitophilus zeamais Motsch. (Coleoptera: Curculionidae)

The maize weevil Sitophilus zeamais Motsch. is an important pest of maize that attacks the grain both in the field and during storage. The damage caused by the maize weevil S. zeamais on maize landraces, Amarelo Antigo, Asteca, Caiano, Carioca, and Ferrinho, was evaluated by no-choice tests under laboratory conditions. The commercial varieties Sol da Manhã, BR 106, BR 451, and the synthetics PC 0203 and PC 9903 were evaluated for comparisons with the maize landraces. The parameters evaluated were susceptibility index, number of weevil progeny, development time, weevil progeny dry weight, and grain dry weight loss. The landraces were more susceptible to the maize weevil as compared to the commercial varieties. Based on the cluster analysis, two groups of susceptibility to the maize weevil were observed: one of more susceptible populations formed by local landraces and BR 451, and another less susceptible, with commercial varieties, synthetics, and the landrace Amarelo.

Responses of Coffee berry borer, Hypothenemus hampei (Ferrari)(Coleoptera: Scolytidae), to vertical distribution of methanol: ethanol traps

Captures of the coffee berry borer (CBB) Hypothenemus hampei (Ferrari) were assessed in traps in the field. IAPAR designed traps [plastic bottles (2 L) lured with methanol:ethanol (1:1) in a vessel] were placed either at 0.5, 1.0 and 1.5m high from the ground or simultaneously tested in the 2004 fructification season. Traps placed at the three heights trapped 5.5 times more CBB than the others, mostly at the traps placed at 0.5 m (75%). Treatments using the IAPAR designed trap placed at 1.2 m high; IAPAR trap with a white plastic plate above (IAPAR modified I) at 1.2 m high; IAPAR at 0.5 m high and two additional vessels at 1.0 and 1.5m high (IAPAR modified II) and T-163 trap [three red plastic cups (300 ml) and a red plastic plate as a cover] lured with M:E (1:1) at 1.2m height were compared in the vegetative (2005) and fructification (2006) periods. IAPAR modified II (dispenser vessels placed at 0.5, 1.0 and 1.5 m) trapped more beetles than the remaining types (2.72 times more beetles than IAPAR design); and IAPAR modified I traps trapped more beetles than T 163 and IAPAR traps in the vegetative period. In the reproductive period, IAPAR modified II trapped less beetles than IAPAR and IAPAR modified I. In 2007 vegetative season, IAPAR modified II trap were compared with IAPAR trap and trapped 2.8 times more beetles. The positive responses to a vertical distribution of the volatile attractants in the vegetative period of the planting allow the development of more efficient trapping systems for CBB.

Comportamento de larvas de Diabrotica speciosa (Coleoptera: Chrysomelidae) em resposta ao CO2 e a plântulas de espécies cultivadas

Responses of Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) larvae to CO2 and their behavior when exposed to host and non host plants were studied in the laboratory. First instar larvae of D. speciosa were used. In a first bioassay, larvae preferred the treatment with CO2, from the reaction of the potassium bicarbonate and acetic acid, in opposition to distillated water. When the behavior of the larvae was observed in response to host plants, a significant higher number of turns was found in corn and popcorn than in common beans, soybean, wheat and sorghum. Sorghum differed from all other treatments with a lower number of turns. Similar values were found in popcorn and corn. The greater distances ranged were found on oats in comparison to pop corn, corn, common beans and sorghum. After contact with sorghum seedlings larvae did not present searching behavior because they fell from the seedling or no movements were saw seen.