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This 10-yr field study examined prolonged dormancy (dormancy of more than 1 yr) in Colorado potato beetles, Leptinotarsa decemlineata (Say), from Upstate New York. The research focused on whether the life cycle of the Colorado potato beetle could reduce the effectiveness of crop rotation as a pest management tactic. One set of experiments quantified variation in the occurrence and duration of prolonged dormancy in a natural population. A second set of experiments tested the effect of artificial selection for increased incidence of prolonged dormancy. Of the ≈12,600 unselected beetles in the field cages overall survival (= % emergence) averaged 56.5 ± 18.4% (mean ± SD, range = 23.5–84.3%, n = 19 cages). Most (97.7%) of the emerging beetles surfaced after one winter; the remainder (2.3%) emerged after more than one winter in dormancy. The range of variation in the incidence of prolonged dormancy among the experimental cages during the 10-yr period was 0–7.2%. The incidence of emergence from prolong...

A field-based experimental study examined the roles of temperature and moisture in the dry-season embryonic dormancy and postdormancy hatching of the spittlebug Deois flavopicta Stal from Brazil’s dry interior region. The results show that dormancy consists of two discrete parts: an initial period of diapause that persists from April to the beginning of July, followed by a period of postdiapause quiescence that prevails until the rainy season begins (usually October). Low temperatures during the early part of the diapause period accelerates diapause development, whereas contact with liquid water determines the timing of postdiapause hatching. Soil temperatures during June and July and the relative humidity of the soil during August and September strongly affect overwintering survival and thus are important in determining the size of the nymphal population after dormancy. The findings indicate that, like hibernation and aestivation in temperate-zone insects, dry-season dormancy in tropical insects is a dynamic state that is influenced by seasonal changes in key environmental factors.

Trash-carrying chrysopids within the genus Ceraeochrysa appear well-protected from intraguild predation, and several species show excellent potential for commercialization in the United States and Latin America. To facilitate their mass production and marketing, we evaluated how Ceraeochrysa cincta (Schneider), Ceraeochrysa cubana (Hagen), and Ceraeochrysa smithi (Navas) perform when larvae are reared on several different prey regimens, including two currently used to rear chrysopids commercially [eggs of the moths Anagasta kuehniella (Zeller) and Sitotroga cerealella (Olivier)]. All regimens that included the moth eggs gave substantially and significantly faster (by 3–4 d) preimaginal development and sometimes larger adults than did a diet of aphids [ Myzus persicae (Sulzer)]. Compared with S. cerealella, A. kuehniella eggs resulted in a slight (a1 d) but significant acceleration in larval development, but no effect on adult body size or reproductive traits. The prey regimens that we tested yielded no significant variation in either larval or imaginal survival; however, they affected the survival of the combined prepupal, pupal, and preemergent adult stages of C. cubana and C. smithi. Our results indicate that the three Ceraeochrysa species could be mass reared readily on either species of moth eggs ( A. kuehniella or S. cerealella ) commonly used as prey in the mass production of Chrysoperla. The findings also underscore that Ceraeochrysa is not restricted to homopteran prey.

The survival of Heterorhabditis bacteriophora Oswego Poinar, Steinernema carpocapsae NY001 Weiser, and S. glaseri NC1 Steiner varied in relation to the bulk density of a sandy loam soil. Survival of H. bacteriophora decreased linearly with time (4–70 d) and quadratically with increasing bulk density, whereas S. glaseri survival decreased linearly with time, but increased quadratically with increasing bulk density. Survival of S. carpocapsae decreased quadratically with time, but was unaffected by bulk density. H. bacteriophora and S. glaseri infected larvae of the greater wax moth, Galleria mellonella (L.) for up to 10 wk after soil inoculation, and the incidence of infection showed no significant variation in relation to bulk density or time. In contrast, infection rate by S. carpocapsae increased with bulk density and decreased with time. The combined effects of soil texture and bulk density on movement these of nematode species generally decreased as the bulk density of 3 soil textures increased. However, the degree to which soils of high bulk density reduced movement differed among species and soil textures: H. bacteriophora was the least restricted; whereas, S. carpocapsae was the most restricted. All 3 species moved significantly more in sandy loam, than in loam or silty clay loam. Although movement was reduced at relatively high bulk densities, survival of the 3 nematode species was high. Rates of movement and infection by the nematodes were strongly correlated with the amount of soil pore space having dimensions similar to or greater than the diameters of the nematodes. In a sandy loam soil, H. bacteriophora moved at least 18 cm within 4 d of soil inoculation across all bulk densities tested, whereas S. carpocapsae moved only 9 cm at the 3 lower densities and

To determine if the phenology of Empoasca fabae (Harris) includes reproductive diapause, the progeny of females collected in Louisiana were reared under various conditions of photoperiod and temperature. Adults were paired, and the oviposition of each female was recorded for 40 d at 4-d intervals. Short day lengths resulted in a lower proportion of E. fabae ovipositing, a longer preoviposition period, and a decreased rate of oviposition. These responses constitute evidence for the induction of reproductive diapause. To determine whether reproductive diapause is expressed in northern populations in the field, 4th and 5th instars from New York state were reared at intervals through summer and fall. and tested for response to photoperiod. The proportion of E. fabae females becoming reproductively mature decreased as the season progressed. Less than 50% of field-reared females became gravid after mid-July. In the laboratory, reproductive maturation in field-reared females was retarded by short day lengths, but not by long day lengths. The induction of reproductive diapause in late summer supports the hypothesis that E. fabae engages in a diapause-mediated southward migration to its overwintering area.

Short- and long-term storage (shelf-life) of diapausing Chrysoperla carnea (Stephens) adults can be achieved efficiently through manipulation of photoperiod, temperature, and diet. Short-term storage (up to 10 wk) was accomplished under short day lengths (10 :14-8:16 [L :D] h) at temperatures up to 21°C. Storage of 10-18 wk was accomplished at relatively low storage temperatures (5-10°C). Long-term storage (18-31 wk or longer) was most efficient when pupae or young adults experienced a decrease in day length and diapausing adults were maintained under very short day length (8 :16 [L :D] h) at 5°C ; under these conditions, reproduction by poststorage adults equaled that of unstored adults. High survival and excellent poststorage reproduction occurred when the animals received a high carbohydrate diet before storage and a carbohydrate and protein diet during and after storage.

Variation in postdiapause emergence patterns of Colorado potato beetle adults over six consecutive years at a single site was only partially explained by cumulative soil heat units. However, soil moisture measured at a depth of 15 cm and daily rainfall accounted for much of the unexplained variation in yearly emergence patterns. We hypothesized that emergence of overwintered beefles was a two-stage process consisting of thermally regulated postdiapause development followed by moisture-driven emergence from the soil. To test this hypothesis we constructed two simulation models that mirrored these processes. One model used soil moisture measured at a depth of 15 cm to drive emergence, while the other used daily rainfall for the same purpose. Both models were able to represent the field data; however, the best congruence was achieved when rain was an independent factor. Because rainfall was a better determinant of moisture, the dynamics of moisture at the soil surface may be of great importance to the beetle. Greater precision in model simulations could probably be achieved by improving the way in which soil moisture dynamics are depicted.

Diapausing adults of Chrysoperla carnea Stephens were stored at low temperature (5°C) under short daylengths (10:14 [L:D] h) for 31 wk with little maintenance. Rates of survival were very high (≈97%), and both males and females retained high reproductive potential. Shortly after transfer to warm, long-day conditions, >90% of the pairs produced fertile eggs: initiation of oviposition after storage was synchronous and predictable. Subsequently, depending on the duration of storage, females oviposited an average of 230–350 eggs during the first 30 d of oviposition (≈50–70% of the eggs produced by unstored females). Except for one group that was stored for 31 wk, high levels of fertile oviposition persisted for ≈45 d after storage. Cold storage of C. carnea benefits biological control efforts by providing flexibility and efficiency in mass-production to meet peak seasonal demands for eggs or young larvae; an alternative method of shipping C. carnea to distributors who choose to harvest eggs (or young larvae) for sale; and a reserve supply of stock if insectary colonies fail or dwindle. It also makes standardized stock available for use in long-term ecological, physiological, or genetic research.

The multivoltine hawthorn lace bug, Corythucha cydoniae (Fitch), undergoes a reproductive diapause from late summer to spring. In the laboratory, the critical photoperiod for diapause induction fell between 13:11 and 14:10 L:D h. High temperature averted diapause in a proportion (≍25%) of the females that were reared under short daylengths; high temperature also appeared to diminish the intensity of diapause in females reared under daylengths near the critical photoperiod. Diapause in this long-day insect expresses several features that are typical of imaginal diapause. For example, the preimaginal stages perceive and respond to diapause-inducing photoperiods, but the adult is the ultimate sensitive stage. Diapause is induced earlier in females that experience short daylengths as fourth and fifth instars than in females that are transferred to short days as adults. Mature females remain sensitive to diapause-inducing photoperiods for at least 2 wk after emergence. Photoperiod also appears to playa role in diapause maintenance.

The life cycle of the greenhouse whitefly, Trialeurodes vaporariorum Westwood, consists of an egg stage, 4 nymphal instars, and an adult. It is convenient to divide the 4th stage into 3 substages: the “early” 4th instar, the transitional substage, and the unemerged pharate adult. The developmental rate of 2nd, 3rd, and “early” 4th whitefly nymphal instars, parasitized by Encarsia formosa Gahan, does not differ significantly from that of unparasitized hosts. However, developing parasites arrest whitefly development during the transitional and pharate adult substages of the 4th stage.

Under greenhouse conditions there is a direct relationship between the density of glandular trichomes on aphid-resistant potato clones ( Solanum tuberosum x S. berthaultii , F3 and S. berthaultii ) and the adverse effectson 11 aphidophagous species. These negative effects include a reduction in adult coccinellid searching time, a decrease in the distance newly hatched chrysopid and coccinellid larvae move, and a decrease in the number of eggs Chrysopa oculata oviposit on highly pubescent foliage. Survival of the parasitoid Aphidius matricariae decreases when adults are exposed to moderate and high densities of glandular pubescence. However, the severe negative effects observed under greenhouse conditions are attenuated in the field. Field studies show that natural enemies and moderate levels of glandular pubescence are compatible mortality factors in the management of aphids on potatoes. Thus, although these greenhouse and laboratory studies elucidate the behavioral responses of natural enemies to glandular trichomes, they inadequately predict the effects of glandular pubescence on beneficial insects in the field.

Plant feeding enhanced survival and shortened developmental times and preoviposition period of the predaceous pentatomid Podisus maculiventris (Say). When potato foliage was provided in addition to prey (Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae) and water, preimaginal survival increased by 27.5%. Also, developmental time from second instar to adult eclosion was reduced by 2.4 days, and the preoviposition period was shortened by 1.4 days. Adults of both sexes were significantly larger and males were significantly heavier when potato foliage composed part of the nymphal diet. Plant feeding has both positive and negative biological features that should be considered in evaluating predaceous hemipterans as biological control agents.

The Mexican and Colombian biotypes of the egg parasitoid Edovum puttleri Grissell have similar rates of development under temperatures from 18 to 29°C. They require approximately 215 degree-days ( K ) above a developmental threshold ( t ) of 9.9°C. A biophysical model that simulates temperature–development relationships over a wide range of temperatures estimates that high temperature inhibition occurs between 31 and 32°C. Survival at 15°C was higher for the Mexican than the Colombian biotype. Under all temperatures tested, development was slightly (2 days maximum) faster under short daylengths than under long daylengths. The Mexican biotype offers two advantages to biological control programs: 1) its relatively high survival at 15°C may make it a better choice for release in potato-growing regions of the northern United States, and 2) it may provide genetic variability for selecting or breeding for improved tolerance to low temperatures.

Between 18.3 and 29.4°C, preimaginal developmental rates of the exotic egg parasitoid Edovum puttleri were linearly related to temperature. Survival was very low at 15.6°, and there was no survival at 12.8°C. In the laboratory, development required 217 ± 6 degree-days above a lower threshold of t = 9.9°C; in three field tests during the summers of 1982 and 1983, emergence occurred within 1 to 3 days of the predicted dates. Development was only slightly affected by photoperiods between LD 16:8 and 10:14; no dormancy was observed in our laboratory or in field experiments. This strain of E. puttleri , originally from Colombia, South America, appears to be poorly adapted to the climate of the northeastern United States. Furthermore, laboratory studies suggest that it is not especially welladapted to insect resistant Solanum plants bred for high densities of glandular pubescence. Our results indicate the need for further research with E. puttleri in two areas: the development of methods of inundative releases, and searches for biotypes that develop and overwinter at low temperatures and that can tolerate Solanum species bearing glandular trichomes.

Adalia bipunctata L. has low developmental thresholds ( t ) for postdiapause and nondiapause development that adapt it to activity early in the season. Postdiapause reproductive development leading to oviposition requires an accumulation of 87 degree-days ( K ) above a relatively low developmental threshold temperature ( t ) of 6.8°C. Overwintering adults disperse and initiate oviposition during early to mid-May. The linearly derived ( t ) and ( K ) values of 263 ± 9.0 degree-days above 9.0°C for preimaginal development and daily maximum-minimum temperatures from outdoors accurately predicted outdoor developmental rates. Preimaginal development outdoors during June and July required 269 ± 12 degree-days above 9.0°C under conditions of excess prey. In the field, there are two to three generations per year in the Ithaca, N.Y., area. The critical photoperiod for diapause induction in the Ithaca, N.Y., (~42°N) population lies between LD 13:11 and LD 14:10 (23°C). Short daylengths maintain diapause, and during autumn the duration of diapause is quantitatively related to photoperiod. Diapause completion does not require chilling: during winter-early spring. photoperiod may exert some influence on the timing of diapause termination.

Dormancy is significant in determining the seasonal interactions between the thelyotokous braconid parasite Perilitus coccinellae and its coccinellid host, Coleomegilla maculata . The parasite's autumnal diapause is maintained by short daylengths and it ends in 50% of the population by the winter solstice. Low temperatures are not required to terminate diapause. The autumnal-hibernal diapause of the host is maintained by short daylengths. By the end of Mar. the photoperiodic control of diapause ends in 50% of the beetles; subsequently temperature and availability of prey determine when oviposition begins. P. coccinellae parasitizes the overwintering C. maculata population twice: during Sept., before the beetles form overwintering aggregations, and again in spring after the beetles disperse.

The parasite, Encarsia formosa , oviposits in all 4 instars, including the late 4th instar and the pharate adult (=pupa of previous workers), of the greenhouse whitefly, Trialeurodes vaporariorum . When each host stage is exposed individually, percentage parasitism is significantly greater in 3rd instar, “early” 4th instar, and transitional substage whiteflies than in 1st instars, 2nd instars, or pharate adults. Although E. formosa 's eggs develop and hatch within all sessile whitefly stages (i.e., 1st to pharate adult), the parasite's larval development does not proceed past the 1st instar until after the host reaches the 4th instar. Subsequently, E. formosa completes its life cycle and emerges as an adult from 4th instar whiteflies. A comparison of the four host instars showed that 3rd instar, “early” 4th instar and transitional substage whiteflies are the most suitable for parasitization because they give (a) the highest percentage E. formosa emergence, (b) the greatest parasite survival, and (c) the lowest host mortality (including host killing). Also, E. formosa egg and larval development is significantly faster in the 3rd instar, “early” 4th instar and transitional substage than in earlier host stages or the pharate adult stage. These results are directly applicable to increasing the efficiency of mass-rearing and colonization of E. formosa by allowing precise timing of parasite introduction.

To define the selective toxicity of pirimicarb (5,6-dimethyl-2-dimethylamino-4-pirimidinyl dimethyl carbamate) for use in integrated control, the toxicity of a 50% wettable powder and a fumigant were tested vs. 1 pest and 3 beneficial arthropod species. Although pirimicarb was highly toxic to the green peach aphid ( Myzus persicae (Sulzer)) it was not toxic to Chrysopa carnea Stephens, Encarsia formosa Gahan, and Phytoseiulus persimilis Athias-Henriot. Therefore, pirimicarb could be a particularly useful pesticide in a multipest, integrated control program for greenhouse crop production where aphids, whiteflies and mites coexist.