Biological control of stored-product insects in commodities, food processing facilities and museums

Non-chemical control methods have gained importance in integrated pest management, as policies aiming to minimize the application of residual chemical insecticides are being adopted by many companies, and a growing market of organic produce. The associations of organic farming have established self-restrictions concerning chemical control. Examples are given of how organically producing farms and processing companies function without synthetic chemical pesticides. Both non-chemical control methods for complete disinfestations and for suppression of re-infestation or residual infestations are needed. For complete disinfestations, heat treatment of buildings is now more widely used. Data on heat-tolerance of storedproduct pests and an example for a heat treatment of a mill will be given. For high-value products such as spices, tea or medical plants, deep freezing is applied. Temperature data are needed to apply product-specific freezing conditions to obtain complete control at the core of the bulk. An integrated management strategy is needed to keep products free from infestation following disinfestations, along the whole chain from the storage of raw products to the consumer. Biological control is a part of that strategy. A new branch of the biological control industry is developing in Europe. Natural enemies for stored-product pests are now produced in The Netherlands, Germany and Switzerland. Traditional pest control companies are using insect parasites and predators more and more to control stored-product insects, indicating an adoption of biological control. Homeowners throughout Europe are purchasing online Trichogramma sp. to control moth pests. Biological control is especially attractive to processing facilities that are not willing to stop production for pest control operations. Small farms with bulk grain stores that are not gas-tight apply parasitoids as well. Recommendations for the application of natural enemies are presented for these examples. Finally, recent developments on natural enemies both for stored-product pests, e.g. flour beetles, and museum and wood boring pests are presented.Keywords: Stored-product Pests, Material Destroying pests, Temperature modification, Biological contro

Search of X-ray emission from roAp stars: The case of gamma Equulei

The detection of X-ray emission from Ap stars can be an indicator for the presence of magnetic activity and dynamo action, provided different origins for the emission, such as wind shocks and close late-type companions, can be excluded. Here we report on results for gamma Equu, the only roAp star for which an X-ray detection is reported in ROSAT catalogs. We use high resolution imaging in X-rays with Chandra and in the near-infrared with NACO/VLT that allow us to spatially resolve companions down to ~1" and ~0.06" separations, respectively. The bulk of the X-ray emission is associated with a companion of gamma Equu identified in our NACO image. Assuming coevality with the primary roAp star (~900 Myr), the available photometry for the companion points at a K-type star with ~0.6 M_sun. Its X-ray properties are in agreement with the predictions for its age and mass. An excess of photons with respect to the expected background and contribution from the nearby companion is observed near the optical position of gamma Equu. We estimate an X-ray luminosity of log L_x [erg/s] = 26.6 and log(L_x/L_bol) = -7.9 for this emission. A small offset between the optical and the X-ray image leaves some doubt on its association with the roAp star. The faint X-ray emission that we tentatively ascribe to the roAp star is difficult to explain as a solar-like stellar corona due to its very low L_x/L_bol level and the very long rotation period of gamma Equu. It could be produced in magnetically confined wind shocks implying a mass loss rate of ~10^(-14) M_sun/yr or from an additional unknown late-type companion at separation ~0.4". If confirmed by future deeper X-ray observations this emission could point at the origin for the presence of radioactive elements on some roAp stars.Comment: Accepted for publication in Astronomy & Astrophysics (5 pages

Field trials with the diatomaceous earth SilicoSec® for treatment of empty rooms and bulk grain

Diatomaceous earths (DE) are fossil diatoms (phytoplankton) that contain silicon dioxide (SiO2), the particles absorb the waterproof lipids from the arthropod cuticle resulting in death through desiccation. The DE SilicoSec® is registered in Germany. The field trials presented here were performed in order to determine (1) the efficacy of SilicoSec® under temperate Central European climatic conditions, (2) the distribution in empty rooms and (3) the possible effect of different surface materials. For empty room treatment, a 41 m² storage room was treated with 20 g/m², the total surface treated including walls was 145 m². At 19 sampling points the amount of DE on the floor was determined. Distinctly less DE attached to the walls compared to the floor, and an uneven distribution on the floor ranging from 2.6 to 49.5 g/m² with a mean±SD of 15.4±14 g/m² per sampling point was measured. Additionally, test pieces with 5 different surface types were placed in the treatment room prior to the treatment. Adult Tribolium confusum and Cryptolestes ferrugineus were placed on all surfaces at 15 to 19°C and 65-81% r.h.. Mean corrected mortality after 14 d in T. confusum and C. ferrugineus was 94% and 65%, respectively. No significantly different mortality was recorded for T. confusum depending on surface type, but in C. ferrugineus significantly less beetles (20%) died on concrete flagstone compared to natural flagstone, glazed ceramic flagging, plywood and porcelain stoneware. For bulk grain, 10 t of wheat were treated with either 0.7 kg/t or 2 kg/t DE. Sitophilus granarius, Oryzaephilus surinamensis and C. ferrugineus adults were placed in vials with treated wheat together with data loggers and placed deep within the bulk for 19 d. Corrected mortality was around 90% for all treatments except for S. granarius at the lower dose where 60% mortality was achieved only. Keywords: Diatomaceous earth, Efficiency, Cryptolestes ferrugineus, Sitophilus granarius, Oryzaephilus surinamensi

The nature of the recent extreme outburst of the Herbig Be/FU Ori binary Z CMa

Z CMa is a binary system which consists of two young stars: A Herbig AeBe component "Z CMa NW" embedded in a dust cocoon and a less massive component "Z CMa SE", which is classified as a FU Orionis type star. Recently, the system showed the largest outburst reported during the almost 90 years of available observations. During the recent outburst we detect that the Z CMa system is polarized by 2.6% in the continuum and emission line spectrum, with a position angle still perpendicular to the jet. From the high level of polarization we conclude that the outburst is associated with the dust embedded Herbig AeBe NW component. The main result of our studies is that the bolometric luminosity of Z CMa remained surprisingly constant during the recent "outburst". We conclude that either the geometry of the cavity through which the light escapes from the cocoon has opened a new path, or that the screen of dust, which reflects the light toward the observer became more efficient causing the observed increase of the visual brightness by about 2.5 magnitudes.Comment: letter to A&A, accepted 17/12/200

Weak magnetic fields in central stars of planetary nebulae?

It is not yet clear whether magnetic fields play an essential role in shaping planetary nebulae (PNe), or whether stellar rotation alone and/or a close binary companion can account for the variety of the observed nebular morphologies. In a quest for empirical evidence verifying or disproving the role of magnetic fields in shaping PNe, we follow up on previous attempts to measure the magnetic field in a representative sample of PN central stars. We obtained low-resolution polarimetric spectra with FORS 2 at VLT for a sample of twelve bright central stars of PNe with different morphology, including two round nebulae, seven elliptical nebulae, and three bipolar nebulae. Two targets are Wolf-Rayet type central stars. For the majority of the observed central stars, we do not find any significant evidence for the existence of surface magnetic fields. However, our measurements may indicate the presence of weak mean longitudinal magnetic fields of the order of 100 Gauss in the central star of the young elliptical planetary nebula IC 418, as well as in the Wolf-Rayet type central star of the bipolar nebula Hen2-113 and the weak emission line central star of the elliptical nebula Hen2-131. A clear detection of a 250 G mean longitudinal field is achieved for the A-type companion of the central star of NGC 1514. Some of the central stars show a moderate night-to-night spectrum variability, which may be the signature of a variable stellar wind and/or rotational modulation due to magnetic features. We conclude that strong magnetic fields of the order of kG are not widespread among PNe central stars. Nevertheless, simple estimates based on a theoretical model of magnetized wind bubbles suggest that even weak magnetic fields below the current detection limit of the order of 100 G may well be sufficient to contribute to the shaping of PNe throughout their evolution.Comment: 16 pages, 11 figures, 3 tables, accepted for publication in A&A; References updated, minor correction