Ultramorphological Comparison of Proboscis and Associated Sensilla of Scotogramma trifolii and Protoschinia scutosa (Lepidoptera: Noctuidae)

The proboscis is an important feeding organ for the glossatan moths, mainly adapted to the flower and non-flower visiting habits. The clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are serious polyphagous pests, attacking numerous vegetables and crops, resulting in huge economic losses. However, the feeding behavior and mechanisms of the adult stage remain unsatisfactorily explored. In this study, the proboscis morphology of S. trifolii and P. scutosa are described in detail using scanning electron microscopy, with the aim of investigating the morphological differences and feeding behavior of these two species. The proboscises of S. trifolii and P. scutosa are similar in morphology and structure and are divided into three zones (Zone 1–3) based on the morphological changes of the dorsal legulae. Three sensillum types are located on the proboscises of both species, sensilla chaetica, sensilla basiconica, and sensilla styloconica. Significant differences were observed in the length of the proboscis and each zone between these two species, as well as in sensilla size and number. Based on the morphology of the proboscis and associated sensilla, S. trifolii and P. scutosa are potential flower visitors, which was also reinforced by the pollen observed at the proboscis tip. These results will strengthen our understanding of the structure of the proboscis related to the feeding behavior of Noctuidae.

SPATIAL AND TEMPORAL VARIABILITY IN SEX ATTRACTANT TRAP CATCHES OF SCOTOGRAMMA TRIFOLII (LEPIDOPTERA: NOCTUIDAE) IN RELATION TO ITS BIOLOGY IN MANITOBA

Tests of intertrap variability in catches of moths of the clover cutworm, Scotogramma trifolii (Rottenberg), were conducted by placing two traps baited with an artifical sex attractant at 1 mi (1.6 km) intervals to form a grid covering 25 mi2 (64 km2) near Domain, Manitoba. The 50 traps (2/location) placed near the intersects of the grid were baited with a blend of Z-11-hexadecen-1-yl acetate and Z-11-hexadecen-1-ol. This blend was 98.6% species-specific for S. trifolii. Moth catches varied between traps and flights, but the ranking of the traps by catch was consistent during any given flight period. Up to 35 traps would be required within an area of 64 km2 (1 trap/1.8 km2) to give a population estimate within 20% of the true mean. Temperature influenced both the initiation of the flights and the number of moths caught at any given time, but there were no correlations between flights and precipitation or wind. Crop type influenced catches of S. trifolii only when moth populations were large. The catch of second generation moths averaged 9.8× the catch of first generation moths. The consistency of this relationship indicates that the annual differences in population density are controlled by variations in winter survival. The latter was linked to the induction of diapause which is governed by daylength during the larval development of the second generation.

VARIATION IN CATCHES WITH SEX ATTRACTANT OF THE CLOVER CUTWORM, SCOTOGRAMMA TRIFOLII, AND ARMY CUTWORM, EUXOA AUXILIARIS (LEPIDOPTERA: NOCTUIDAE), DUE TO TRAP LOCATION

Sex attractant traps for males of the clover cutworm, Scotogramma trifolii (Rottenberg), on farms in southern Alberta caught more moths within crops or on fallow than those near or within the farmyards except for traps immediately on the south side of the yard For males of the army cutworm, Euxoa auxiliaris (Grote), two trap placements in open areas were more effective than locations within the farmyard, again with the exception of the traps on the south side of the yards. Traps 2 m high caught significantly fewer moths than those at 1 m or ground level and the crop in which the trap was placed had no significant influence on catch of either cutworm.

SEX ATTRACTANT FOR CLOVER CUTWORM, SCOTOGRAMMA TRIFOLII: FIELD TESTS WITH VARIOUS RATIOS OF Z-11-HEXADECEN-1-YL ACETATE AND Z-11-HEXADECEN-1-OL, AND WITH VARIOUS QUANTITIES OF ATTRACTANT ON TWO TYPES OF CARRIERS

Catches of male clover cutworm moths with Z-11-hexadecen-1-yl acetate containing 10.8 to 25.0% Z-11-hexadecen-1-ol decreased linearly as the percentage of alcohol increased. The largest catches were with the acetate containing 10.8% alcohol, and at a concentration of 5 mg/rubber carrier. This bait was effective in the field for at least 4 weeks Catches of moths with the attractant on polyethylene carriers were independent of the attractant concentrations, and were significantly less (P < 0.01) than with the same attractant concentrations on rubber carriers.

Damage to Cabbage by the Clover Cutworm, Scotogramma trifolii (Rott.) (Lepidoptera: Phalaenidae)

The clover cutworm, Scotogramma trifolii (Rott.), has been recorded from a wide variety of host plants, but there are few records in the literature associating it with cole crops. Riley (1893) recorded it from cabbage in Maryland. Gibson (1915) recorded it from turnip and cabbage in Canada. Forbes (1951) and Frost (1955) listed cabbage as a host plant in New York and Pennsylvania, respectively. In 10 years' studies on caterpillars on cabbage in the Ottawa VaIley, 1949 to 1958, numbers of the clover cultworm on cabbage were almost always negligible. However, in the early summer of 1956 it occurred throughout the area in significant numbers, and in a study field of early cabbage at Merivale, Ontario, caused sufficient damage to affect the market value of the crop.