Caio Fabio Stoffel Efrom

Spatial distribution of parasitism on Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae) in citrus orchards

Many species of microhymenopterous parasitoids have been registered on Phyllocnistis citrella, the citrus leafminer. The present study aimed to identify the spatial distribution pattern of the native and introduced parasitoids of P. citrella in two citrus orchards in Montenegro, RS. The new shoots from 24 randomly selected trees in each orchard were inspected at the bottom (0-1.5 m) and top (1.5-2.5 m) stratum and had their position relative to the quadrants (North, South, East and West) registered at every 15 days from July/2002 to June/2003. The leaves with pupae were collected and kept isolated until the emergence of parasitoids or of the leaf miner; so, the sampling was biased towards parasitoids that emerge in the host pupal phase. The horizontal spatial distribution was evaluated testing the fitness of data to the Poisson and negative binomial distributions. In Montenegrina, there was no significant difference in the number of parasitoids and in the mean number of pupae found in the top and bottom strata (chi2 = 0.66; df = 1; P > 0.05) (chi2 = 0.27; df =1; P > 0.05), respectively. In relation to the quadrants, the highest average numbers of the leafminer pupae and of parasitoids were registered at the East quadrant (chi2 = 11.81; df = 3; P < 0.05), (chi2 = 10.36; df = 3; P < 0.05). In the Murcott orchard, a higher number of parasitoids was found at the top stratum (63.5%) (chi2 = 7.24; df =1 P < 0.05), the same occurring with the average number of P. citrella pupae (62.9%) (chi2 = 6.66; df = 1; P < 0.05). The highest number of parasitoids and of miners was registered at the North quadrant (chi2 = 19. 29; df = 3; P < 0.05), (chi2 = 4.39; df = 3; P < 0.05). In both orchards, there was no difference between the numbers of shoots either relative to the strata as well as to the quadrants. As the number of shoots did not varied much relative to the quadrants, it is possible that the higher number of miners and parasitoids in the East and West quadrants would be influenced by the higher solar exposure of these quadrants. The data of the horizontal spatial distribution of the parasitism fit to the negative binomial distribution in all sampling occasions, indicating an aggregated pattern.

Fertilidade e longevidade de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)em genótipos de milho

Spodoptera frugiperda (J. E. SMITH) is one of the main corn crop pest. Neverthless, studies about its biology in the sweet corn crop are scarce. This study aimed to evaluate the effect of the genotypes ELISA, BR 400 (sweet corn) and BR PAMPA (field corn) in the reproductive phase of S. frugiperda concerning: pre-oviposition, oviposition and post-reproduction periods; number of ovipositions/female and eggs/oviposition; eggs viability; incubation period; interval between ovipositions and longevity. In laboratory conditions (25 ± 1°C; 70 ±10% RH; 12 hours photophase), 60 larva/genotype were fed with leaves of three genotypes. From the pupae, 15, 20 and 24 couples were formed in ELISA, BR 400 and BR PAMPA, respectively. The number of ovipositions per female and eggs per oviposition was daily registered. Differences between the genotypes ELISA, BR 400 and BR PAMPA, respectively, were not noticed, concerning: pre-oviposition (4.78; 3.94; 3.94 days); oviposition (7.55; 6.5; 6.11 days) and post-reproductive (4.87; 4.64; 5.5 days) periods; number of ovipositions/female (6.33; 5.25; 4.88) and eggs/oviposition (216.72; 215.03; 226.02); eggs viability (59.02; 69.76; 60.81%); interval between ovipositions (0.63; 0.86; 1.0 days); longevity of male (15.22; 13.62; 13.29 days) and female (16.33; 14.06; 15.65 days) with offspring and of the male (19.17; 13.67; 13.86 days) and female (16.43; 8.25; 19.37 days) without offspring. The incubation period of the eggs generated by females whose caterpillars were kept in BR 400 genotype was numerically longer than the others.

Side-effects of pesticides used in the organic system of production on Apis mellifera Linnaeus, 1758

This study aimed to evaluate the effects of pesticides, used in the organic system, on Apis mellifera under laboratory conditions. Four multiple (0.25x, 0.5x, 1x and 2x) concentrations as recommended by they manufacturers of the following products: Rotenat CE®, Pironat®, Biopirol 7M®, Organic neem®, Natuneem® and lime sulfur were tested by topical application and ingestion. Of all the products and concentrations tested, only the lime sulfur (5000 ml 100L-1 and 10000 mL 100L-1 of water) by ingestion, and Rotenat CE® (1200ml 100L-1 of water) on topical application were considered slightly harmful for A. mellifera, as the classification of IOBC/WPRS for the laboratory tests.

Larval and pupal stage of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in sweet and field corn genotypes

Spodoptera frugiperda, the fall armyworm, is a very significant polyphagous pest due to the damages it causes, and control difficulties. Lack of information about its impact on sweet corn motivated a comparison of its biology, with respect to the larval and pupal stages, among the genotypes ELISA, BR 400 (sweet corns), and BR PAMPA (field corn). In laboratory conditions (25 +/- 1 masculine C; 70 +/- 10% RH; photophase 12 hours), 35 caterpillars were individualized and fed daily with 3.14 cm(2) sections of corn leaves from the referred-to genotypes, cultivated in plots in the experimental area of the Departament of Fitossanidade, UFRGS, Porto Alegre, RS from October to November 2000. The caterpillars were weighed daily; after each molt, the cephalic capsules were collected and measured (in width), to establish growth rate; pupae were weighed and sexed when 24 hours old. The duration of the larval instars, the pupal sex ratio, and the mortality of larvae and pupae were evaluated. In the first three instars there were no differences registered in capsule width. In the fourth and fifth instars, capsules of caterpillars kept in BR 400 were smaller. The weight of caterpillars and pupae, instar duration and sex ratio did not differ among the genotypes. Pupal phase duration was less in females kept in BR 400. Mortality was greater in the larval phase in ELISA and in the pupal phase in BR PAMPA.

Distribuição espacial de posturas de Cosmoclopius nigroannulatus Stål (Hemiptera: Reduviidae) em Nicotiana tabacum L. (Solanaceae)

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 Stal 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%) and the Taylor Power Law Index (b = 0.9633). Most of the eggs (68.4%) 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.

Effects of kaolin and limestone on infestation of South American fruit fly in citrus orchards

ABSTRACT This study evaluated the effects of applying mineral films on infestations by Anastrepha fraterculus (Wied.) (Dip.: Tephritidae) in Céu and Valencia sweet oranges (Citrus sinensis). The treatments consisted of either kaolin or liquid limestone (calcium carbonate) at 20% concentrations, both with addition of 0.1% Break Thru® adhesive spreader, plus a control treatment (no applications). The spraying was performed in the Céu orchard in Pareci Novo, state of Rio Grande do Sul (RS), Brazil, from March to April 2015, and in the Valencia orchard in Taquari, RS, from May to August 2015. Each tree received 1.5 L of the respective formulations, applied by spraying. Fruits from the canopy and from the ground under each tree were harvested and arranged in containers with sand and stored in a chamber or a greenhouse for 30 days. The sand was then sieved and the fruits opened to remove the larvae and/or pupae. The physical-chemical attributes of the fruits harvested at the last sampling (during fruit harvest) were analysed. In both orchards, fruits collected from the canopy had similar numbers of pupae + larvae per canopy for kaolin and calcium carbonate treatments, and both were lower than in the control treatment. The fruits showed no physiological changes resulting from the treatments.