Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae), a newly recorded parasitoid of the tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in Argentina

We report the first record of Neochrysocharis formosa (Westwood) parasitizing larvae of the tomato moth, Tuta absoluta (Meyrick), in tomato crops in Northern Buenos Aires Province, Argentina. Tomato moth larvae were sampled during four consecutive growing cycles, between 2003 and 2005, in 10 sites. Neochrysocharis formosa was present only in organic outdoor and protected crops, and predominantly during the late season. Parasitism rates varied from 1.5 percent to 5 percent. The finding of this species is a new record for Argentina and South America, and T. absoluta is a new host record.

Temporal and spatial variation of Stenoma cathosiota Meyrick (Lepidoptera: Elachistidae) caterpillar abundance in the cerrado of Brasilia, Brazil

The caterpillars of Stenoma cathosiota Meyrick feed on Roupala montana Aubl. (Proteaceae) in the cerrado of the Distrito Federal, Brazil. They construct shelters by joining leaves of the plant where they feed and pupate. The caterpillars are parasitized by a wasp (Hymenoptera: Brachonidae), which emerges from the pupae. Caterpillar abundance and parasitism frequency were associated in an area of frequently burned cerrado (biennial fire) and in another area that burns sporadically (1987 and 1994). For S. cathosiota, the variation among years in a single area, with sporadic fires, was greater than the variation among areas with different fire regimes. Caterpillar abundance among years was significantly different in the area that burns sporadically (chi² = 24.06; df. = 1; P = 0.000). However, there were no significant differences on caterpillar abundance between areas for the same period (chi² = 3.45; df. = 1; P = 0.063). Parasitism frequency was high, reaching 29 percent of the collected caterpillars, and did not differ among areas. The great temporal variation in abundance of lepidopteran caterpillars in the cerrado makes it difficult to determine the effects that fire exerts over this fauna.

As lagartas da mariposa Stenoma cathosiota Meyrick alimentam-se de folhas de Roupala montana Aubl. (Proteaceae) em áreas de cerrado do Distrito Federal. Elas constroem abrigos juntando folhas da planta onde se alimentam e empupam. São parasitadas por uma vespa (Hymenoptera: Braconidae) que emerge da pupa. A abundância de lagartas de S. cathosiota e a freqüência do parasitismo foram comparadas em duas áreas de estudo: uma com queimadas freqüentes (bienal) e a outra com queimadas esporádicas (1987 e 1994). Na área com baixa freqüência de queimada, a variação na abundância das lagartas entre anos foi significativamente diferente (chi² = 24,06; gl. = 1; P = 0,000). No entanto, a variação na abundância de lagartas entre áreas, para o mesmo período de tempo, não diferiu estatisticamente (chi² = 3,45; gl. = 1; P = 0,063). A freqüência do parasitismo foi alta, ocorrendo em 29 por cento das lagartas coletadas e não diferiu entre as áreas. A grande variação temporal na abundância de lagartas no cerrado dificulta a determinação dos efeitos do fogo sobre essa fauna.

Susceptibility of diamond back moth, Plutella xylostella (L) to entomopathogenic nematodes.

Eight entomopathogenic nematode species / strains, Steinernema glaseri (steiner), S. carpocapsae (Weiser), S. feltiae (Filipjev), Steinernema sp. Ecomax strain, Heterorhabditis bacteriophora (Pioner), Heterorhabditis sp. Ecomax strain, two locally isolated strains called as JFC and TFC were tested against the final instar larvae of diamond back moth, Plutella xylostella (L.). All nematodes were found pathogenic. However, H. bacteriophora was adjudged the most pathogenic amongst the test nematodes on the basis of LD50 (9.16 IJS/larva), LT50 (43.26 hr), Lex T50 (3.24 hr) and the propagation potential (average of 271.42 IJS/mg) on the host body weight.

Bioelectrical activity of citrus flower moth prays citri and host plant selection for oviposition

Electroantennogram [EAG] and oviposition responses of the citrus flower female moth, Yponomeuta prays citri to various citrus flower volatile chemicals were tested as possible attractants or deterrents for oviposition. This was also coupled with analytical chromatographic techniques to identify the organic pure compounds in the citrus flowers with the EA recording. Dose response relationships were established to compare the relative receptor sensitivities using different concentrations of these individual pure components and correlate them with ovipositional activities. The obtained results indicated that the volatile odors from different citrus flowers may activate [e.g. Limonene and Citronellol] or inhibit [e.g. Nerol, Terpineol, B-Caryophyllene, Methylantheranlate and Geraniol] the females to lay eggs. A good correspondence was found between oviposition and single sensillum EAg response. In conclusion, the sensory cues that mediate the P.Citri ovipositional response include visual and chemical information. The visual information [flower's shape, colour and size] direct the insect to land on the flower. Contact chemoreceptors present on the insect's antenna appeared to be involved in the assessment of flower surface chemistry which directs the insect to oviposit or deterred the unsuitable plants. Finally the insect's ovipositional response in mediated by a complex mixture of compounds of certain fixed concentrations instead of a single compound. The variation of these concentrations may change or reverse this response and hence it may serve in biological control of this insect