Effect of Irradiation on Queen Survivorship and Reproduction in the Invasive Fire Ant Solenopsis invicta (Hymenoptera: Formicidae) and a Proposed Phytosanitary Irradiation Treatment for Ants

We studied radiation tolerance in queens of the red imported fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae) to identify a dose that prevents reproduction. Virgin or fertile queens were collected from Santa Fe and Formosa provinces in Argentina and reared in the laboratory in microcolonies. Virgin queens were irradiated at 0 (control), 70, 90, 120, or 150 Gy, and fertile queens were irradiated at 0, 60, 125, and 190 Gy, and then followed for 11 wk in the microcolonies to evaluate survival and reproduction. Virgin queens lay trophic eggs that do not hatch, whereas fertile queens lay eggs that hatch and develop into brood. In general, queen oviposition and survival decreased with increasing irradiation dose. For virgin queens, no eggs were laid by irradiated queens after the third week, whereas the control queens continued laying eggs throughout the 11-wk experiment. For fertile queens, only one larva and no pupae was observed in the 60 Gy treatment and no larvae or pupae were observed in the 125 and 190 Gy treatments, whereas a total of 431 larvae and 83 pupae were produced by untreated control queens during 11 wks. Survivorship of virgin and fertile queens was similarly reduced by irradiation treatment. These results with S. invicta are consistent with previous findings for three other invasive ants, Wasmannia auropunctata (Roger), Pheidole megacephala (F.), and Linephithema humile (Mayr), that are hitchhiker pests on fresh horticultural commodities. A radiation dose of 150 Gy is proposed as a phytosanitary treatment to prevent reproduction in ants.

Food-dependent exercise-induced anaphylaxis to pistachio

We report the case of a 16-year-old male who, 30 minutes after beginning to play football with previous ingestion of pistachio nuts, experienced an anaphylactic reaction. Prick-by-prick test with roasted pistachios was negative. Specific IgE antibodies to pistachio, cashew nuts and mango were negative. An open oral challenge test with pistachio in resting conditions was negative. Treadmill ergonometric stress in a fasting state and 60 minutes after a meal without pistachio gave negative results. A specific food exercise challenge 60 minutes after ingestion of 50 g pistachio nuts was positive, showing mild diffuse erythema and small wheals in face and thorax. To the best of our knowledge, this is the first described case of specific food dependent exercise-induced anaphylaxis to pistachio. Negative allergologic tests is an unusual condition, since most cases appear to be IgE-mediated. In this case, a positive specific food exercise challenge test provided a definite diagnosis.

Occupational asthma caused by grass pea used in the industrial processing of parquet

BACKGROUND

although grass pea belongs to the leguminoseae family, allergic reactions to its flour have rarely been described. Clinical and immunological studies were performed to confirm a type I hypersensitivity mechanism in a case of occupational asthma to grass pea flour exposure, used in the industrial processing of parquet.

METHODS

occupational asthma was diagnosed according to patient history, PEFR monitoring and a specific bronchial challenge test. Skin prick test with an aqueous grass pea flour extract, specific IgE determinations (CAP assay) and IgE immunoblot tests were performed.

RESULTS

skin prick test with the extract showed a positive immediate response, and negative response in controls. Specific IgE to grass pea was positive (9.57 KU/l). Immunoblotting demonstrated the presence of specific serum IgE that recognized 3 proteins in the extract (MW 46, 32 and 28 kDa). PEFR monitoring showed positive results. Bronchial challenge test with the extract elicited an isolated immediate response.

CONCLUSIONS

as far as we know this is the first time that IgE mediated occupational asthma caused by grass pea is reported and it is also the first time that its allergens are characterized. Grass pea flour might constitute a relevant occupational allergen in this unreported source of exposure in parquet manufacturers.

Contact urticaria caused by heat-sensitive raw fish allergens

Patients allergic to fish usually present with skin reactions after handling raw fish. Less frequently, these reactions are seen without symptoms after oral intake, often in chefs and food handlers. We have attempted to explain the skin selectivity of such reactions in a 36-year-old woman with contact urticaria after handling raw fish. We obtained aqueous extracts of raw and cooked fish (sole and hake) for in vivo (prick test) and in vitro (SDS-PAGE, IgE Immunoblot) tests. Prick-by-prick test, 20-min closed patch test, rub test with fresh and cooked fish (sole, hake and cod) and specific IgE (CAP-system) to sole, cod and hake were performed. The strength of positive reaction to raw fish was greater than to cooked fish on both prick and prick-by-prick testing. Rub tests showed positive responses only to raw fish. Specific IgEs to sole (45 KU/l), hake (66.9 KU/l) and cod (18.7 KU/l) were obtained. IgE immunoblot recognized 3 antigens of 25, 48, 56 kDa in raw sole and 1 of 42 kDa in raw hake extracts. No IgE binding was observed with the cooked extracts or control sera. Our findings strongly suggest a Type-I hypersensitivity to fish. Immunoblot analyses demonstrated a loss of specific IgE binding to cooked extracts. We have reported a case of contact urticaria caused by heat-sensitive raw-fish allergens in a patient who probably became sensitized via the cutaneous route.