Alexandre J. Cattelan

Bacteria in the Gut of Southern Green Stink Bug (Heteroptera: Pentatomidae)

Abstract Laboratory studies with the southern green stink bug, Nezara viridula (L.), indicated the presence of bacteria Klebsiella pneumoniae (Schroeter) and Enterococcus faecalis (Andrewes & Horder) in the crop/stomach (ventriculus 1–3; V1–V3), and possibly Pantoea sp. in the gastric caeca (ventriculus 4; V4). Culturable bacteria were most abundant in V1–V3, and their abundance was drastically reduced in V4. The variable pH in the gut did not affect the presence of bacteria. Elimination of bacteria from the gut, by using the antibiotic kanamicin, did not affect nymphal developmental time or cause mortality, but it did cause reduced weight at adult emergence.

Effect of relative humidity on emergence and on dispersal and regrouping of first instar Nezara viridula (L.) (Hemiptera: Pentatomidae)

Laboratory studies with 1st instar of southern green stink bug, Nezara viridula (L.) indicated that relative humidity (RH) greatly affected nymph emergence and survivorship up to the 2nd instar, reaching the maximum value (approximately 90%) with RH of > 80%. At 60% RH, 60% of the nymphs emerged and survived, while with 0% RH only approximately 15% of eggs hatched, and most nymphs died. Emerged nymphs from egg masses placed in plastic boxes with a gradient of humidity remained on egg shells for ca. one day. After this period, they dispersed and regrouped on top of shells 6.8 +/- 0.67 times, until they abandoned the shells toward the source of humidity, avoiding the water-saturated areas. Duration taken for each rearrangement (dispersal + regroup) increased with time, with a range of approximately 26 min to 44 min. The mean duration of the grouping behavior on egg shells after each rearrangement decreased from approximately 102 min (1st) to 24 min (6th and last grouping). The rearrangement behavior of 1st instars on top of egg shells apparently compensates for the water loss of nymphs.

Potential use of antibiotic to improve performance of laboratory-reared Nezara viridula (L.) (Heteroptera: Pentatomidae)

The antibiotic streptomycin added to the drinking water at a concentration of 125 mg/ l during nymphal development of Nezara viridula (L.) (Heteroptera: Pentatomidae)accelerated the development in ca. 2 days, increased survivorship, and doubled adult longevity; nymph survivorship and adult body weight were not affected when compared to control insects. Streptomycin has potential in rearing N. viridula, especially in improving quality of field-collected adults, by mitigating the introduction of pathogenic bacteria, and improving the quality of the population.

Brazilian Trials to Evaluate the Effects of Soybean Reinoculation

Although Brazilian soils are very poor on N, the nitrogen fixation process is able to fully supply the N plant demands. Reinoculation with selected strains promotes increases in nodulation, nodule occupancy and yield.

Competitividade Nodular de Estirpes de Bradyrhizobium spp. em Cultivares de Soja sob Diferentes Disponibilidades Hídricas

O objetivo do trabalho foi avaliar a competitividade nodular de estirpes de Bradyrhizobium spp. em cultivares de soja sob diferentes disponibilidades hidricas a campo. Foi realizada analise conjunta dos dados de duas safras (2006/07 e 2007/08), com dez cultivares de soja (BR 16, Embrapa 48, BRS 133, BRS 134, BRS 245 RR, BRS 247 RR, BRS 183, BRS 184, BRS 214, e BRS 232), que foram submetidas a tres disponibilidades hidricas (1 - DHER, deficit hidrico nos estadios reprodutivos; 2 - CNC, condicoes normais de campo e 3 - IRR, irrigado) em delineamento experimental de blocos ao acaso, em parcelas subdivididas, com quatro repeticoes. Os nodulos foram tipificados pelo metodo de ELISA, com antissoros das estirpes SEMIA 5079, SEMIA 5080, SEMIA 587 e SEMIA 5019. As estirpes inoculadas (SEMIA 587 e SEMIA 5019) foram mais competitivas para nodulacao em relacao as estirpes naturalizadas no solo. A estirpe SEMIA 587 foi a de maior ocupacao nodular, inclusive quando houve limitacao hidrica nos estadios reprodutivos. A SEMIA 5080 (nao inoculada) foi a que apresentou a menor ocupacao nodular entre as estirpes analisadas.