1. Dicyphus hesperus Knight (Heteroptera: Miridae) nymphs were fed from egg hatch to the adult stage on Ephestia kuehniella eggs provided either alone or in combination with tomato leaves or with a supplementary water source.2. Only 6% of individuals completed nymphal development on a diet of eggs alone. In contrast, a high proportion of nymphs completed development on a diet of eggs when either tomato leaves (97%) or a supplementary water source (88%) were provided.3. The development times of nymphs given access to leaves were signi®cantly shorter than those of nymphs given access only to supplementary water.4. Adult female D. hesperus that were given access to tomato leaves prior to feeding trials consumed signi®cantly more eggs in a 4-h period than females that were dehydrated before trials. Dehydrated females that were allowed access to water for 3 h before trials consumed an intermediate number of eggs. 5. Plant feeding or access to some other water source is required for prey feeding, growth, and development in D. hesperus, and acquisition of water is proposed as a primary function of plant feeding. In addition, D. hesperus derives nutrients from plant feeding that increase the rate of nymphal development, although nymphs cannot complete development when provided only with tomato leaves.6. Three simple models are presented of feeding behaviour in predatory Heteroptera where the amount of plant feeding either decreases, increases, or is constant as a function of the amount of prey feeding. The models are discussed with reference to the results and the probable multifunctional nature of plant feeding in predatory Heteroptera.

No abstract

Dicyphus hesperus Knight (Heteroptera: Miridae) is an omnivorous predator used to control pests of greenhouse vegetables. Plant preferences and life history traits were studied using nine plant species: . Plants were selected from among potential target crops, natural hosts, plants used for mass rearing, and plants on which D. hesperus has not been reported. Plant preference was measured by multi-choice host plant selection and oviposition assays. Development and reproduction were measured on each of the plant species on both a plant diet alone and on a plant diet supplemented with Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. Dicyphus hesperus females and nymphs expressed a preference for some plants over others. Plant preference ranged from low preference plants, such as Z. mays , V. sativa , C. coronarium , and C. annuum , to high preference plants such as V. thapsus , N. tabacum , and S. albotomentosa . When E. kuehniella eggs were supplied, there were few differences in the development time and fecundity of D. hesperus among plants, with the exception of corn and broad bean, where fecundity was lower. On a plant diet alone, nymphs were able to complete their development on V. thapsus , C. annuum , and N. cataria . However, mortality and development time were much lower on V. thapsus than on C. annuum and N. cataria . On most of the plant species D. hesperus did not lay any eggs when fed on a plant diet alone. On V. thapsus , females laid a few eggs and lived longer than when fed on prey. Dicyphus hesperus females tended to prefer host plants on which nymph survival without prey was greatest.

The effects of water stress (produced by water deprivation and prey feeding) on plant feeding were investigated in the omnivorous predator Dicyphus hesperus Knight (Hemiptera: Miridae). The objective was to determine if prey feeding aggravated water deficits and thus increased plant feeding. We measured plant feeding in a factorial experiment where female D. hesperus were prepared for experiments by providing or withholding water and/or prey for 24 h. We then evaluated the amount of plant feeding on Nicotiana tabacum seedlings by the direct observation of insects at three different densities of the prey, Ephestia kuehniella eggs. The amount of plant feeding, as measured by frequency of plant feeding bouts and time spent plant feeding during observation, was significantly greater for water-deprived individuals than for those that had been provided with water. Individuals that had been provided with prey fed on plants at a significantly higher frequency than prey-deprived individuals at two of the prey densities used in the experiment. These results support the hypothesis that plant feeding in zoophytophagous Hemiptera facilitates prey feeding by providing water that is essential for predation.

No abstract

No abstract

fIID CANADIAN ENfOMOLOGIST. 43 Macnocemrus TRIDESCENS, tr. Sp.Length .r3 of an inch. Head piceous, the mouth parts, inciuding the clypeus, tawny ; antenn€ rufo-cinereous, the basal joint yellowish. flhorax light rufcrus, darkest on posterior part, paler beneath; lvings hyaline rvith strong iridescence, the veins, costa and stigma fuscous ; feet and legs straw color, the last tarsi of hind feet a little darker. Abdomen rather slender, rufo-piceous, under side of middle joints slightly tawny; ovipositor not exserted. Under the rnicroscope a fine grayish pubescence is seen on all parts of the insect, sparse on the abdomen and legs, but profuse on the antenne and wings, not interfering r,vith the iridescence on the latter. Pupa with the host. I)escribed from 5 n.rales and 7 females reared from trvo larve from an elm tree, that were taken to be Etryonia subsignarla.

Cumulative temperature requirements and development thresholds were determined for two populations of Dicyphus hesperus Knight, 1943 to compare their suitability for use in biological control in greenhouse vegetable crops. The populations were from near Summerland, British Columbia, Canada (49°36′N, 119°40′W, at 334 m elevation) and from near Woody, California, United States of America (35°42′N, 118°50′W, at 500 m elevation). Eggs of the California (CA) population had a higher cumulative temperature requirement for hatch than those of the British Columbia (BC) population. Males of the CA population had a slightly lower cumulative temperature requirement for development from hatch to adult than males of the BC population. The populations did not differ with respect to development thresholds. Males of the CA population experienced higher mortality during development at 35 °C than BC males or females of either population. Males and females of both populations developing at 35 °C were significantly smaller than those developing at more moderate temperatures. The differences between populations with respect to development were biologically trivial. With respect to the effects of temperature on development time under greenhouse conditions, the two populations appear to be equally suitable for use in greenhouses.