Functional response and preference of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in Ceratitis capitata and Anastrepha fraterculus (Diptera: Tephritidae).

Diachasmimorpha longicaudata is the most used braconid in biological control programs for Tephritidae fruit flies worldwide. The aim of this work was to assess the functional response and preference of this parasitoid to larvae of Ceratitis capitata and Anastrepha fraterculus, in different densities of hosts. The functional response of females of D. longicaudata was assessed, independently, in two hosts (third instar larvae of C. capitata or A. fraterculus), in seven densities 1, 3, 5, 10, 25, 35 or 55 larvae of fruit flies per one female of parasitoid exposed in unit of artificial parasitism, for three hours, in at least 20 repetitions. The species showed a Type III functional response regardless of the density of host larvae, in both species, indicating that they are feasible hosts for multiplication of the parasitoid, under the conditions tested. The number of individuals parasitized and the percentage of female emergence were superior in A. fraterculus, when compared to C. capitata. Parasitism in field and progeny of female parasitoids can be incremented using larvae of A. fraterculus in the rearing of D. longicaudata.

Diversity of scale insects (Hemiptera, Coccomorpha) in ten varieties of olive trees (Olea europaea L.) in Southern Brazil.

Olive production (Olea europaea L.) is a recent activity in Brazil and studies on the adaptability of olive trees varieties in the States are required. One of the problems that can hamper the development of olive trees is the incidence of pests, such as scale insects (Hemiptera, Coccomorpha). In this study, the associated scale insect species were found in ten varieties in an olive grove located at the Research Center of the Serra do Sudeste Region (30º33'15"S, 52º23'45"W) in Brazil. The surveys were carried out twice in each season (2013-2014). Six species of armored scale insect (Diaspididae) and two soft scales (Coccidae) were determined. Saissetia oleae (Coccidae) with 88.15% and Aspidiotus nerii (Diaspididae) with 5.85% occurred in all varieties of olive trees. The varieties Arbequina, Frantoio and Cipressino were with greater richness of scale insects, the highest values of diversity occurred in Frantoio, Arbequina and Picual; in Alfafara, Arbosana and Coratina there was a high dominance of one species (S. oleae).

Distribuição espacial de posturas de Cosmoclopius nigroannulatus StÕl (Hemiptera: Reduviidae) em Nicotiana tabacum L. (Solanaceae) / Spatial distribution of Cosmoclopius nigroannulatus StÕl (Hemiptera: Reduviidae) egg masses in Nicotiana tabacum L. (Solanaceae)

A seleção de locais adequados à oviposição, garantindo boas condições de desenvolvimento da prole, ocorre em muitas espécies de insetos. Para predadores a estratégia de realizar posturas em vários locais da cultura é esperada, pois possibilita a colonização mais abrangente da área, diminuindo também a competição intra-específica. O conhecimento dessa estratégia é importante para a determinação do papel do predador como agente de controle de populações fitófagas. Este trabalho objetivou caracterizar posturas de Cosmoclopius nigroannulatus StÕl no campo e identificar seus padrões de distribuição espacial. De agosto de 1999 a abril de 2000, em um cultivo experimental de fumo (Nicotiana tabacum), em Porto Alegre, RS, foram monitoradas 270 plantas de fumo do tipo Virgínia, variedade K326, identificadas por coordenadas alfa-numéricas. A posição das posturas era registrada na cultura e na planta em relação ao estrato (inferior, mediano e apical) e à estrutura (haste e folha). Após a eclosão das ninfas recolhiam-se os córions para contagem do número de ovos. Encontraram-se 176 posturas no campo, em 34 ocasiões de amostragem. O padrão de distribuição das posturas na quase totalidade das amostras ajustou-se à distribuição aleatória, tanto pelo índice de dispersão I (97,1 por cento) como pela Lei da Potência de Taylor (b = 0,9633). A maioria das posturas foi encontrada no terço apical (68,4 por cento) e na face adaxial das folhas. Constatou-se o número médio de 13,1 ± 4,98 ovos/postura. A disposição das posturas no cultivo experimental aponta para um bom aproveitamento de recursos existentes.

The search for oviposition sites with good conditions for offspring development is common in many insect species. Predators usually lay eggs in various places in a culture to allow a more complete colonization and to reduce intraspecific competition. This knowledge is important to determine the role of predators in the control of phytophagous populations. The present work aimed at characterizing Cosmoclopius nigroannulatus StÕl egg masses in tobacco field, and at identifying their spatial distribution pattern. A field with 270 tobacco plants (Nicotiana tabacum, Virginia type, var. k326), was surveyed from August 1999 to April 2000. The experimental field was located in Porto Alegre, Rio Grande do Sul, Brazil. Each egg mass found had its position recorded in relation to the culture (coordinates), the plant vertical stratum (inferior, middle and apical) and plant structure (steam and leaf). After nymphal emergence, the corions were collected and brought to the laboratory to record the egg number/mass. A total of 176 egg masses were found in 34 sampling occasions. The egg masses dispersion pattern followed a random distribution in almost all occasions, considering both the Dispersion Index I (97 percent) and the Taylor Power Law Index (b = 0.9633). Most of the eggs (68.4 percent) were found on the plant apical third. The adaxial leaf side was also preferred for oviposition. The mean number of eggs/mass was 13.1 ± 4.98, ranging from two to 22. The egg masses distribution pattern in the experimental plot suggests an adequate usage of the available resources.