Cabbage Looper

NYS IPM Type: Vegetables IPM Fact SheetThe cabbage looper is native to the United States and feeds on many cultivated vegetables, including all members of the cabbage family. This pest survives the winter only in the Gulf States. The adults migrate northward annually, arriving in northeastern United States and Canada anytime from early July to late August, depending on the weather and wind patterns. There are one to three generations in the northeastern states depending on the time of arrival and temperature in late summer and early fall

Effect of Age Structure on the Outcome of Viral Epizootics in Field Populations of Imported Cabbageworm (Lepidoptera: Pieridae)

The effect of larval age on the progress of epizootics of a granulosis virus was examined in field populations of imported cabbageworm, Artogeia rapae (L.), in 1985 and 1986. An enzyme-linked immunosorbent assay (ELISA) was used to follow the progress of disease in three larval age classes beginning 2-3 d after treatment. On virus-treated cabbage, late second and early third instars were more liable to infection than were first and final instars. In laboratory experiments, potted cabbage plants were treated with virus in the same way that field plots had been, and leaves were fed to three age classes of larvae at three temperatures for 18-23 h. Fewer larvae developed disease when given access to leaves at 16°C than at 22 or 28°C. Fewer first instars became infected than third and fifth instars. Third instars were most likely to become infected at all temperatures. The data suggest that virus should be directed at second and third instars rather than at larvae at hatchin

Factors Altering the Temporal and Within-Plant Distribution of Coccinellids in Corn and Their Impact on Potential Intra-guild Predation

In New York, the primary coccinellid in corn and sweet corn (Zea mays, L.) has historically been Coleomegilla maculata (DeGeer). However, Harmonia axyridis (Pallas) has also been observed the last few years. The objectives of this study were to document the level of establishment of both species in corn and sweet corn and to understand their interactions. The temporal and within-plant distributions of all coccinellids were recorded for 3 yr. The results indicated that H. axyridis and C. maculata were the only abundant coccinellids in corn and sweet corn, with adults and larvae of both species having distinct temporal and within-plant distributions. C. maculata adults were found earlier in the season and lower on the plant than H. axyridis adults. Larvae of both species were often found at the same time and were lower on the plant than their respective adults. Temporal distributions of both species were correlated to crop maturity, aphid density, planting date, and corn type, but not to nearby vegetation. The within-plant locations were correlated to crop maturity, aphid density, planting date, nearby vegetation, and the presence of conspecific coccinellids. While the distribution of each population was unique, some C. maculata and H. axyridis shared time and space, providing the potential for intra-guild predation. An encounter between H. axyridis and C. maculata was most likely to occur when the corn had high aphid populations during pollen shed. These extraguild food sources minimize intra-guild predation, allowing these two species to co-exist in New York corn and sweet corn field

Predation of Ostrinia nubilalis (Lepidoptera: Crambidae) Eggs in Sweet Corn by Generalist Predators and the Impact of Alternative Foods

Generalist predators are common in most agricultural cropping systems. However, pest control from these predators is often overlooked as a component of integrated pest management (IPM) because the extent of predation is generally unknown and difficult to assess. In western New York sweet corn (Zea mays L.), the primary predators are Orius insidiosus (Say), Coleomegilla maculata (DeGeer), and Harmonia axyridis (Pallas). European corn borer [Ostrinia nubilalis (Hübner)] is the primary insect pest. The objectives of this study were to compare O. nubilalis egg predation rates for these three species and to understand how egg predation by these predators is affected by the availability of alternative food. Laboratory data indicate that all three predators feed on O. nubilalis eggs. C. maculata consumed more eggs than H. axyridis or O. insidiosus. Immatures of C. maculata and O. insidiosus readily completed development on a diet of O. nubilalis eggs, but H. axyridis larvae could not complete development on this diet. The presence of corn leaf aphids [Rhopalosiphum maidis (Fitch)] and corn pollen reduced egg predation per insect for some stage of all species. The reduction in O. nubilalis egg predation associated with the presence of aphids was confirmed in field cage studies and was similar among the coccinellid populations tested. Field studies comparing aphids, predator populations, and O. nubilalis egg predation show that reduced egg predation per insect more than offsets the higher populations encountered when aphids and pollen are numerous, resulting in less biological control of O. nubilalis when alternative foods are availabl

Management of Swede Midge with Cultural Controls and Selected Insecticides

The swede midge (SM) is a serious pest of cabbage, broccoli and cauliflower.  The first occurrence of SM in North America was in Ontario , Canada (2000) and has forced some farmers to cease growing crucifers.  In 2005 we verified that SM was present in Cattaraugus, Erie , Genesee, Madison , Monroe , Niagara, Orleans , St. Lawrence and Wyoming Counties .  There is an urgent need to test management practices.  We conducted a series of tests to determine the role of soil type and moisture on emergence of swede midge adults from the soil and whether selected insecticides on transplants could be an effective way of reducing the movement of contaminated plants

Antixenotic Resistance of Cabbage to Onion Thrips (Thysanoptera: Thripidae). I. Light Reflectance

Onion thrips (Thrips tabaci Lindeman) has become a significant pest of cabbage (Brasssica oleracea L.) in regions with a dry continental climate. Thrips-resistant cabbage varieties have been developed in breeding programs, but the mechanisms of resistance remain largely unknown. Antixenosis, one of the three resistance mechanisms, may play a role but no plant trait has been identified as a source of antixenosis. A series of studies were conducted to identify resistance mechanisms in this insect-crop interaction and to seek plant traits that were correlated to resistance. In this first article of the series, the result of studying antixenosis and overall resistance of cabbage and the correlation between antixenosis and light reflectance characteristics are reported. There were distinct differences in the overall resistance to thrips between the six cabbage varieties studied. There were more pronounced differences between varieties based on the number of damaged head leaves compared with the use of damage ratings as a measure of overall resistance. Varieties also differed in their level of antixenosis; proportional abundance of thrips adults on head-forming leaves was more closely correlated to overall resistance of cabbage than actual thrips numbers. Some of the variables computed from the recorded reflectance spectra of cabbage were correlated to thrips abundance on head-forming leaves only in the first but not in the second year of this study, suggesting that either spectral characteristics do not affect antixenosis or other variables may affect thrips' responses to spectral cues. Furthermore, multiple spray applications of a kaolin particle-based product significantly changed the light reflectance characteristics of cabbage, but it did not reduce the actual thrips abundance on head-forming leave

A SYSTEM FOR QUANTIFYING BEHAVIOR OF NEONATE CATERPILLARS AND OTHER SMALL, SLOW-MOVING ANIMALS

We have developed a system for recording and quantifying animal behavior on artificial or natural substrates. The system is designed for subjects such as insects and mites with movement rates as high as 4 cm/min. The principle is the same as in automatic stage or sphere centering devices (Berg 1971; Kramer 1976; Thiery and Visser 1986), but the compensations are made manually by an observer who may also simultaneously enter codes for specific behaviors on a microcomputer keypad. Data files produced are analyzed or plotted using programs in SAS® (SAS Institute 1985a) or similar data analysis package

Larval Performance in Relation to Labile Oviposition Preference of Crocidolomia pavonana [F.] (Lepidoptera: Pyralidae) Among Phenological Stages of Cabbage

Crocidolomia pavonana (=binotalis) [F.] demonstrates oviposition peaks in the field that we believe to be correlated with host plant phenology. In previous two-choice laboratory experiments, we found the highest relative proportion of oviposition on cabbage to correspond either to plant growth stages ≈7–8 wk or ≈9–11 wk old, depending on the alternate host plant with which it was presented. In cabbage-only trials, leaves from 7- to 8-wk-old plants were preferred. Inconsistency in preference led to the question of whether oviposition on either cabbage growth stage would confer adaptive advantages in offspring performance. We simulated oviposition on four phenological stages of cabbage in two ways. In a study of complete immature development, growth rate, pupal weight, and survivorship were measured. We also compared food utilization efficiency during the fourth larval instar by analyzing growth rate, efficiency of biomass accumulation, and frass production by analysis of covariance (ANCOVA). For both experiments, cabbage plants of defined phenological stages were designated at the time of oviposition, and larvae were fed from these as plants continued to grow throughout larval development. Our data indicate adaptive advantages in larval growth rate and food conversion efficiency to oviposition on cabbage at ≈7–8 wk from planting. Oviposition on later cabbage growth stages resulted in comparatively poor larval performance. Possible explanations for C. pavonana oviposition behavior in light of these results are discusse

Two Types of Resistance to the Diamondback Moth (Lepidoptera: Plutellidae) in Cabbage

Survival of larvae of the diamondback moth, Plutella xylostella (L.) was reduced on several genotypes of cabbage from the breeding program at Geneva, N.Y. Polar fractions of ethanol extracts of partially resistant lines 2535 and 2503, when incorporated into diet, reduced survival of P. xylostella larvae by 14.9 and 19.0%, respectively. Whether this effect was due to reduced feeding or postingestive toxicity was not determined. Although survival on glossy-leafed line 2518 was very low in the field and larvae on this line failed to form visible feeding mines during the first 72 h after egg hatch, extracts from 2518 had no activity. Survival of larvae confined on leaf disks of 2518 in the laboratory was much greater (80% of controls) than it was on whole plants in the field (0.36% of controls). In the field, neonate P. xylostella dispersed two to three times more rapidly on the leaves of 2518 than on other lines. Resistance to P. xylostella in the lines investigated was therefore due to at least two mechanisms, (1) antibiosis or nonpreference due to extractable compounds present in normal bloom resistant cabbage genotypes, 2503 and 2535, and (2) possible nonpreference for glossy-leafed 2518 by neonate larvae, as suggested by the greater dispersal rates of neonates on these plants. Survival is relatively high on 2518 in leaf disk bioassays in the laboratory, suggesting that nonpreference in combination with environmental stresses to larvae in the field may produce P. xylostella resistance in the glossy 251