Search

Studies related to control of the pink bollworm (PBW) by trapping were conducted on an 80-ha farm located in Phoenix, AZ. Initial laboratory studies of trap efficiency lead to the incorporation of 10% dicrotophos into Stickem® used in traps (ca. 13% increased kill compared to traps with Stickem only). During the period April 29 to Sept. 15, 1975, a trapping program on 36 ha of cotton resulted in the capture of ca. 30,000 ♂ PBW. Nine percent of the acreage attained 10% or greater boll infestations during the season compared to 45–100% for the preceding 1972–74 seasons. Early fruiting cotton (plots of 4 rows × 7.6 m) was no more attractive to PBW than surrounding, less developed cotton. Early season trap catches indicated that male moths congregated in cotton fields regardless of where they emerged.

Diflubenzuron (N-[[(4-chlorophenyl) amino]carbonyl]-2,6-difluorobenzamide), an insect growth inhibitor, was applied at 0.22 and 2.2 kg AI/ha to ‘Deltapine 16’ cotton in field cages. There was no control of the pink bollworm, Pectinophora gossypiella (Saunders), but excellent control of the cotton leafperforator, Bucculatrix thurberiella Busck, at both rates of application, and control of the cabbage looper, Trichoplusia ni (Hübner), at the highest rate.

Studies were conducted to develop a pheromone trap monitoring system for the sweetpotato weevil, Cylas formicarius (F.), in sweet potato, Ipomoea batatas (L.) Lam., in the southern United States. The current studies examined the effects of lure type, age, and their duration in cold storage on weevil collections in traps. We also characterized release rates of pheromone off soxhlet-extracted and nonextracted rubber septa. Most commercially prepared (matrix sheet system) lures and methylene chloride-extracted rubber septa did not differ in their attractiveness to C. formicarius when loaded with 10 μg of pheromone, but they did differ when loaded with 100 μg of pheromone. Traps baited with extracted rubber septa caught more weevils than those baited with matrix sheet lures. In another experiment, weevil counts did not differ among traps baited with rubber septa that were soxhlet-extracted with methylene chloride and those not extracted for septa obtained from two commercial suppliers. Regression parameter estimates from log10 release rate (ng/h) on log10 dosage did not differ among soxhlet-extracted and non extracted rubber septa obtained from one of the suppliers and extracted septa obtained from the other supplier. Lure age, however, did affect attractiveness to C. formicarius. The percentage of weevils caught per night decreased with an increase in lure age for ages between 0 and 80 d. However, nonextracted lures from one of the suppliers can probably be used for monitoring for at least 2 mo in the fleld. Soxhlet-extracted lures from the other supplier lost their attractiveness more rapidly; hence, a shorter replacement time of between 1 and 2 mo is probably sufficient. Time in cold storage did not affect the attractiveness of soxhletextracted rubber septa. Septa loaded with 10 μg of synthetic sex pheromone, sealed in air tight vials and stored in a refrigerator at 5 ± 1°C for >2.2 yr, were as attractive as those stored for only 90 d. The importance of these data in a pheromone trap monitoring program for this weevil is discussed.

In laboratory experiments, adult Pectinophora gossypiella (Saunders) mated as frequently in gossyplure permeated atmospheres as in untreated atmospheres. Male moths with antennae ablated at the basal segment did not mate. Males with 2–5 antennal segments remaining and females with antennae ablated at the basal segment were able to mate but did so less frequently than unaltered moths. Males with only antennal tips removed mated as frequently as untreated males. We concluded that males require olfactory stimulation to mate and that close range chemical communication takes place even in an atmosphere permeated with gossyplure. Moths from preadapted pupae mated as frequently in continuous total darkness as did those held in continuous light, suggesting that visual cues are not essential for mating in this species. Flight activities recorded from field experiments and laboratory observations indicate that male moths fly at random in untreated and pheromone permeated atmospheres. This behavior presumably functions to bring males within some critical distance of calling females where pheromone diffusion gradients provide short range orientational cues. We estimate a large number of random male-female encounters that could result in many matings in normal postdiapause field populations of the pink bollworm. Male random movement may be an effective mate acquisition strategy within a host patch and this behavior may thwart attempts to control the pink bollworm by chemical confusion with gossyplure in fields previously planted to cotton.

Field plots of cotton treated with methyl salicylate or untreated had significantly greater infestations of Pectinophora gossypiella (Saunders) than similar plots treated with phenylacetaldehyde. In laboratory tests, phenylacetaldehyde did not reduce hatch when applied to eggs of the pink bollworm oviposited on cotton leaves. However, laboratory female moths laid ca. 75% of their eggs on untreated plants when caged with treated and untreated cotton plants. Phenylacetaldehyde appears to be an oviposition inhibitor for the pink bollworm and may be useful for control.