Insects as a group occupy a middle ground in the biosphere between bacteria and viruses at one extreme, amphibians and mammals at the other. The size and gen eral nature of insects present special problems to the student of entomology. For example, many commercially available instruments are geared to measure in grams, while the forces commonly encountered in studying insects are in the mil ligram range. Therefore, techniques developed in the study of insects or in those fields concerned with the control of insect pests are often unique. Methods for measuring things are common to all sciences. Advances sometimes depend more on how something was done than on what was measured; indeed a given field often progresses from one technique to another as new methods are discovered, developed, and modified. Just as often, some of these techniques fmd their way into the classroom when the problems involved have been suffici ently ironed out to permit students to master the manipulations in a few labo ratory periods. Many specialized techniques are confined to one specific research laboratory. Although methods may be considered commonplace where they are used, in another context even the simplest procedures may save considerable time. It is the purpose of this series (1) to report new developments in methodology, (2) to reveal sources of groups who have dealt with and solved particular entomological problems, and (3) to describe experiments which might be applicable for use in biology laboratory courses."

Sampling methods in soybean entomology

Annual cropping systems consist of a shifting mosaic of habitats that vary through time in their availability and suitability to insect pests. Agroecosystem instability results from changes that occur within a season with crop planting, development, and harvest. Further instability results from continuous alterations in biotic and abiotic insect life system components and from agricultural inputs. Changes to agroecosystems occur across seasons with changing agricultural practices, changing cropping patterns, and technological innovations. Much of this instability is a result of events unconnected with pest management. The abilities of polyphagous pest species to move among and utilize different habitat patches in response to changes in suitability enable the pests to exploit unstable cropping systems. These pest characteristics determine the location and timing of damaging populations. Habitat suitability is influenced by plant species and cultivar, crop phenology, and agricultural inputs. Pest movement is affected by a suite of intrinsic factors, such as population age structure and mobility, and extrinsic factors, including weather systems and habitat distribution. The life systems of three selected polyphagous pests are presented to demonstrate how an understanding of such systems in agricultural ecosystems improves our ability to predict and hence manage these populations.

Life systems of polyphagous arthropod pests in temporally unstable cropping systems.

An analysis of 29 faunal surveys of spiders found in nine field crops in the United States indicates the presence of 614 species in 192 genera and 26 families . These species represent 19% of the ca . 3311 species occurring in North America . Five families included 61% of the species reported in field crops : Salticidae (89 spp .), Linyphiidae (78), Araneidae (77), Theridiidae (64),and Lycosidae(62) .

Spiders in united states field crops and their potential effect on crop pests

Toxaphene is a complex mixture of polychlorinated monoterpenes with a broad spectrum of pesticidal activity. Before its ban in 1982, it was the most heavily used insecticide in the U.S. and many parts of the world. When dichlorodiphenyltrichloroethane (DDT) was banned in the early 1970s, toxaphene replaced DDT as a major agricultural insecticide (Schmitt et al. 1981). Cumulative world use of toxaphene during the period 1946 to 1974 exceeded 409,000 metric tons (Toxaphene Working Group 1977). Toxaphene was first introduced in the U.S. in 1945 by Hercules Co. as Hercules 3956, a new insecticide to control a variety of insect pests. It was registered for use on more than 277 agricultural commodities and crops to control 167 major insect pests. While its primary use has been on cotton, it has also been sprayed extensively on soybeans and peanuts, and has been used as a cattle dip (Korte et al. 1979). It was used most extensively in the southern and southeastern U.S. (Carey et al. 1978, 1979) where most cotton farming is located. Toxaphene and toxaphene-like preparations (camphachlor, polychlorocamphenes, and strobane) have also been used worldwide and are still used in South America, Africa, Mexico, Romania, Hungary, the Federal Republic of Germany, Poland, and the USSR (Saleh 1987).

Toxaphene: chemistry, biochemistry, toxicity and environmental fate.

1

Projection patterns of olfactory receptor neurons, specifically tuned to the two principal components of the female H virescens sex pheromone blend, and to a third pheromone-like compound of possible antagonistic significance, were examined using a combined electrophysiological and morphological technique




2

The macroglomerular complex consists of four major glomerular subdivisions




3

In the sensillum type containing a receptor neuron detecting the main pheromone component, Z11-16: AL, two cells were present When the sensillum was stimulated with Z11-16:AL, a single axon, stained by a method that selectively stains active neurons, was seen projecting into the large a glomerulus The b glomerulus was innervated by a second neuron in a few double stainings




4

In a second sensillum type, one receptor neuron tuned to the second major pheromone component, Z9-14:AL, was found In these sensilla, one or two receptor neurons of unknown specificity were also observed When the sensillum was stimulated with Z9-14: AL, a single neuron projecting into glomerulus a or two neurons projecting into glomerulus a were most often observed




5

In the third sensillum type, one neuron specifically tuned to Z11-16:AC projected to glomerulus c, and a second cell of unknown specificity projected to the same area




6

The axonal arborizations of different physiological receptor neuron types involved in the detection of the pheromone blend do not display a clearcut morphological separation into different glomeruli in the MGC A separation between neurons detecting attracting and repelling odours was, however, present

Chemical communication in heliothine moths. 5. Antennal lobe projection patterns of pheromone detecting olfactory receptor neurons in the male Heliothis virescens (Lepidoptera, Noctuidae)

Activity of adult bollworms, Heliothis zea (Boddie) and tobacco budworms, H. virescens (F.), was monitored with BL and pheromone traps. Light traps captured far more of both sexes of bollworms than of tobacco budworms; pheromone traps seemed more effective in early season when populations were low. When both species were combined as attractants in the same pheromone traps, significantly fewer moths of each species were captured than when traps contained only 1 species.

Heliothis zea and H. virescens: Moth Activity as Measured by Blacklight and Pheromone Traps

In 1972 and 1973, numerous wild host plants in the Pee Dee area of South Carolina were surveyed for populations of larvae of Heliothis spp. Carolina geranium, Geranium carolinianum L., toadflax, Linaria canadensis L., beard-tongue, Penstemon laevigatus Aiton, and crimson clover, Trifolium incarnatum L., were primary spring hosts; later in the season, beggarweed, Desmodium spp., deergrass, Rhexia spp., morning glory, Ipomoea spp., prickly sida, Sida spinosa L., and bicolor lespedeza, Lespedeza bieolor Turcz., were favored. Only the parasities Cardioehiles nigrieepes Viereck and Campoletis spp. and the disease Spiearia rileyi (Farlow) Charles occurred frequently enough to deter the development of populations of Heliothis spp. in the Pee Dee area of South Carolina.

Heliothis spp.: Larvae and Associated Parasites and Diseases on Wild Host Plants in the Pee Dee Area of South Carolina

Bollworm, Heliothis zea (Boddie), and tobacco budworm, H. virescens (F.), infestations were allowed to build up throughout the 1979 growing season in a 0.81-ha cotton field. The following spring, strips of the field were disked, subsoiled and bedded, or left undisturbed. Measured portions of row in each treatment were then covered with screen covers and observed five times a week for emergence of overwintered moths. An estimated 7,760, 1,746, and 3,007 moths per ha emerged from the undisturbed, double disked, and subsoiled and bedded plots, respectively.

Emergence of Overwintered Heliothis spp. Moths from Three Different Tillage Systems

Phidippus audax Hentz of varying ages were field-collected and observed for feeding on a range of commonly occurring insects. Insects offered to the spiders included crop pests, economically unimportant species, and insect predators. Twenty insect species previously unreported as prey of P. audax were found to be consumed by spiders of various ages. In addition, late-instar and adult P. audax were presented with a series of paired insect prey choices and their feeding behavior was observed. The spiders were found to attack prey selectively, with some species being attacked and consumed readily, whereas others were avoided and still others were only taken occasionally. The coccinellids, Hippodamia convergens Guerin-Meneville and Coleomagilla maculata (DeGeer), were generally avoided, but Geocoris punctipes (Say) was readily attacked and consumed by the spiders. Similarly, bollworm, Heliothis zea (Boddie), larvae were attacked and consumed significantly more often by the spiders than adults of the boll weevil, Anthonomus grandis Boheman.

Observations on Feeding and Prey Selection by Phidippus audax (Hentz) (Araneae: Salticidae)

Prepupae and newly formed pupae of the bollwom, Heliothis zea (Boddie), and the tobacco budworm, Heliothis virescens (F.), were allowed to enter 3 types of soil or were manually buried in the soils and were then exposed to 3 simulated regimes of rainfall. Soil type did not affect emergence, but there were significant differences in emergence when the prepupae were allowed to form their own pupation cells or were manually buried. The depth at which the pupae were buried was insignificant, but the regime of rainfall affected emergence of moths of both species. In prepupal behavior tests, both species moved further from the release point on smooth and packed soils compared to rough, soft soil.

Heliothis spp.: Behavior of Prepupae and Emergence of Adults from Different Soils at Different Moisture Levels

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