In vitro rearing of Campoletis sonorensis, a larval endoparasitoid of Heliothis virescens from egg to third instar in an artificial medium devoid of insect sources

Campoletis sonorensis is a solitary larval endoparasitoid of several Heliothis spp. pests. This study was carried out to develop media devoid of insect sources for in vitro rearing the parasitoid. Trehalose, lysine, threonine, asparagine, glutamine, hydroxyproline, serine, bovine serum albumin, and lactalbumin were beneficial to C. sonorensis. Addition of fresh chicken egg yolk at a low level improved the artificial media. Addition of 20-hydroxyecdysone increased the molting rate, reduced the critical size at molt and decreased development time. Parasitoid development in vitro was dependent on eggs that had been in the host for at least 22 h. Luminosity was also critical for the development of C. sonorensis in vitro. Optimal development occurred in a L14:D10 photoperiod at 43 Lux light intensity. Utilizing the best media and conditions, 100% of the parasitoid larvae reached the second instar and over 37% molted to the third instar. However, no further development occurred.     

In vitro rearing of Toxoneuron nigriceps (Hymenoptera: Braconidae), a larval endoparasitoid of Heliothis virescens (Lepidoptera: Noctuidae) from early second instar to third instar larvae

The early second instar larvae of Toxoneuron nigriceps, a larval endoparastioid of Heliothis virescens, were incubated in artificial rearing media, supplemented with hemolymph of the unparasitized and parasitized fifth instar larvae of the host, H. virescens. The parasitoid larvae were incubated in both a semisolid and liquid form of the artificial rearing medium, and their growth and development were evaluated. The growth in size (increase in length and width), development (molting), and survival of the incubated larvae were observed for 10 days. The incubated larvae exhibited some level of growth in all nine types of media tested, including the control (without host hemolymph). However, ingesting the semisolid rearing media supplemented with the hemolymph from the late fifth instar (day 5, 7 and 9) parasitized host resulted in 100% of the larvae molting to third instars. Some of the in vitro reared third instar larvae demonstrated behavioral changes that could be interpreted as the preparation for cocoon formation or pupation i.e. oral secretion of a whitish material and lots of twisting and turning; however, none produced a cocoon nor pupa.     

Interspecific discrimination and larval competition amongMicroplitis croceipes,Microplitis demolitor,Cotesia kazak (Hym.: Braconidae), andHyposoter didymator (Hym.: Ichneumonidae), parasitoids ofHeliothis virescens (Lep.: Noctuidae)

Interspecific host discrimination by adults, and larval competition among the endoparasitoidsMicroplitis croceipes (Cresson),Microplitis demolitor Wilkinson,Cotesia kazak (Telenga) andHyposoter didymator (Thunberg) were investigated usingHeliothis virescens (F.) as the host. In ovipositional choice tests, the mean number of encounters and ovipositions for unparasitized hosts was not significantly different from the mean number of encounters and ovipositions for parasitized hosts for each treatment combination (P>0.05). Thus, none of the parasitoid species discriminated between host larvae recently parasitized once by a female of another species und unparasitized hosts. However, in all but two cases, females did discriminate between unparasitized hosts and hosts in which an early first instar of the first-attacking species was developing.Cotesia kazak andH. didymator did not discriminate between unparasitized hosts and hosts parasitized by an early first instar ofM. demolitor. Larval competition among these parasitoid species was studied for three time intervals between the first and second species parasitization: 1) second species attack immediately (5–15 sec) after the first; 2) second species attack 24 h after the first; and 3) second species attack 48 h after the first. Time until egg eclosion was shortest forM. demolitor, thenC. kazak, thenM. croceipes, and longest forH. didymator. When the second parasitoid species attacked a host immediately after the first species, the species in which egg eclosion occurred first was the victor more frequently, except whenM. demolitor competed withC. kazak andH. didymator. With a 24 h delay between the first and second species to attack, the older first instar from the first parasitization usually outcompeted the younger first instar from the second attack. A first instar from the second species to attack generally outcompeted the second instar of the first species when the second parasitization had been delayed 48 h. Competiors were eliminated mainly by physical attack, butC. kazak andM. croceipes apparently also killedH. didymator eggs by physiological processes.     

Intraspecific host discrimination and larval competition inMicroplitis croceipes,Microplitis demolitor,Cotesia kazak (Hym.: Braconidae) andHyposoter didymator (Hym.: Ichneumonidae), parasitoids ofHeliothis virescens (Lep.: Noctuidae)

Intraspecific host discrimination and larval competition were studied forMicroplitis croceipes (Cresson),Microplitis demolitor Wilkinson,Cotesia kazak (Telenga), andHyposoter didymator (Thunberg), solitary endoparasitoids of the tobacco budworm,Heliothis virescens (F.). In ovipositional choice tests between unparasitized and parasitized hosts, the mean number of ovipositions for unparasitized hosts was significantly higher than the mean number of ovipositions for hosts parasitized once by a conspecific female forC. kazak andH. didymator, demonstrating that females of these 2 species discriminate against hosts recently (within a few seconds) parasitized by a conspecific female. No significant difference in oviposition occurred between these 2 kinds of hosts forM. croceipes andM. demolitor. Mean percent parasitization by a 2^nd conspecific female was determined at 24, 48, and 72-h delays in time between the 1^rst and 2^nd female attack, and with no delay. Except for the 0 h time delay forC. kazak andH. didymator, percent parasitization by a 2^nd conspecific female generally decreased as the delay in time between the 1^rst and 2^nd female attack increased. When the 2^nd parasitization immediately followed the 1^rst, one parasitoid larva always eliminated the other by physical combat. With a 24 or 48 h delay between the 1^rst and 2^nd parasitization, the younger larva was the victor over the older larva forM. croceipes, M. demolitor andC. kazak in at least 50% of the cases. Elimination of older larvae by younger larvae was by physical attack. However, forH. didymator, the older instar was the victor, and elimination of younger larvae by older larvae was probably through physiological processes. Further, older larvae ofH. didymator apparently killed the eggs of the 2^nd female by physiological processes.      

Ontogeny and reproductive biology of Diadegma semiclausum (Hym.: Ichneumonidae), a larval endoparasitoid of Diamondback Moth,Plutella xylostella (Lep.: Plutellidae)

In this article, the ontogeny and reproductive biology of Diadegma semiclausum (Hym.: Ichneumonidae), an important parasitoid of Plutella xylostella (Lep.: Plutellidae) are described in detail. We did dissect parasitized P. xylostella larvae in phosphate-buffered saline and determine the external morphology of its parasitoid at all developmental stages. The developmental duration of its immature stages, adult longevity, total oviposition period and fecundity of the parasitoid are determined at 24 ± 1 °C, 65  ±  5% R.H., and a photoperiod of 16:8 h L:D. The mean duration of egg and larval stages is 9.56 days and the prepupa and pupa stages last for 8.27 days. In average, female longevity is 1.31 times longer than that of males, and females lay 300 eggs in total. The peak of D. semiclausum oviposition is on the eighth day after mating. The egg loading pattern of D. semiclausum was investigated to determine the parasitoid ‘ovigeny index’ throughout the female's parasitoid lifetime. Initial egg load in immature females (<2 h age) is 1.45 per female and the mean lifetime potential fecundity (total immature and mature oocytes), at four interval ages, is 34. With an ovigeny index value of 0.038, D. semiclausum is considered moderately to strongly synovigenic. In the absence of the host, after 3 days, the number of eggs is decreased in D. semiclausum. Our results demonstrated that there is a negative relation between the ovigeny index and egg resorption in this parasitoid.     

The in vitro development from egg to prepupa of Campoletis sonorensis (Hymenoptera: Ichneumonidae) in an artificial medium: importance of physical factors

A further attempt to improve the in vitro rearing of the solitary larval endoparasitoid Campoletis sonorensis (Hymenoptera: Ichneumonidae) was made after third instars were obtained in previous studies. Respiration was an important factor for the parasitoid's continued development: both small diet volumes that exposed the larval cuticle to air and O(2)greatly improved growth and development of C. sonorensis. Fifth instars were obtained when the parasitoid larvae were reared in medium volumes of 0.25ml and 0.1ml per well. Increasing the O(2) tension of the air resulted in larger larvae and prepupae. The agar layer under the nutritional medium was designed to slowly remove water from the diet. The results indicated that a drier environment was important for the parasitoid at the terminal stage. One percent and 0.8% agar gels, which removed water from the diet more rapidly, provided a drier environment and resulted in improved larval growth compared to the 0.6% agar gel. The detrimental effect of higher concentration of chicken egg yolk mixed in the diet was eliminated by using a dry egg yolk layer covered by an agar layer. This sandwich technique resulted in more parasitoid larvae molting to the final larval instar (5th) and the formation of many prepupae. However, the development of prepupae was premature and none of the fifth instar larvae successfully formed a normal cocoon.     

Campoletis sonorensis [Hym.: Ichneumonidae] as a parasitoid ofSpodoptera frugiperda [Lep.: Noctuidae]: Host stage preference and functional response

The response of the parasitoidCampoletis sonorensis (Cameron) as a natural control agent of the fall armyworm,Spodoptera frugiperda (J. E. Smith), was evaluated at 6 host densities and 2 temperature regime. A type-II functional response was exhibited by femaleC. sonorensis in response to varying densities of all armyworn larvae at both temperatures. Significantly more larvae were parasitized at 25°C for the host densities of 60 and 75, than for the same densities at 30°C. Third instar fall armyworm larvae were found to be the preferred stage for parasitization byC. sonorensis. This research was supported by funds from HATCH project no. H-368 as allocated to the Georgia Agricultural Experiment Station.     

Biologia deMeteorus rubens (Hym.: Braconidae), parasitoide primario deAgrotis ipsilon (Lep.: Noctuidae)

Resumen El desarrollo del bracónidoMeteorus rubens (Nees) se estudió en condiciones de laboratorio sobre las especies de noctuidosAgrotis ipsilon (Hufnagel),A. puta (Hübner),A. segetum (Denis & Schiffermüller),Peridroma saucia (Hübner),Spodoptera littoralis (Boisduval) yAutographa gamma (L.). Las larvas deA. ipsilon yA. puta fueron las únicas adecuadas para el desarrollo del parasitoide. EnA. ipsilon este bracónido parasitó y completó su desarrollo en el tercero, cuarto, quinto y sexto estadios larvarios, mostrando preferencia por los dos últimos estadios. El número de hembras que parasitan, el porcentaje de larvas parasitadas y el número de parasitoides emergidos por hospedante estuvo en relación directa con la edad del hospedante en el momento de la parasitación. En las larvas parasitadas en el tercer estadio el tiempo de desarrollo del parasitoide fue significativamente mayor que en los otros tres estadios. Sin embargo, el estadio en que fueron parasitadas las larvas no influyó en la longevidad de los adultos.      

Microcharops anticarsiae (Hym.: Ichneumonidae) parasitoid ofAnticarsia gemmatalis (Lep.: Noctuidae): Host age preference,sex ratio effects and functional response

Résumé L'endoparasito?deMicrocharops anticarsiae (Hym.: Ichneumonidae), est un des agents naturels de régulation d'Anticarsia gemmatalis (Lep.: Noctuidae). La préférence pour un stade de l'h?te, les effets sur la sex ratio et la réponse fonctionnelle ont été étudiés expérimentalement chezM. anticarsiae pour six densités différentes de l'h?te. Dans des expériences de choix impliquant 2 stades de développement consécutifs ou dans les cas où étaient offerts en même temps les quatre premiers stades larvaires, les femelles du parasito?de n'ont présenté aucune préférence pour un stade donné. Ces résultats montrent que les femelles deM. anticarsiae acceptent tout h?te disponible indépendamment de son stade. La sex ratio présente des différences significatives entre les quatre stades de l'h?te (G_3df=18.21, p<.001). La sex ratio du parasito?de est plus favorable aux femelles chez les larves se développant dans le 4^e stade de l'h?te. Une réponse fonctionnelle de type II a été observée chez les parasito?des femelles en réponse à des densités variables de l'h?te. Ces informations fondamentales concernant les effets de la sex ratio ont montré quel est le stade de l'h?te qui doit être parasité pour obtenir la sex ratio la plus favorable aux femelles, tandis que la réponse fonctionnelle a fourni le taux moyen (38.0±7.5) de parasitisme par femelle. Ces informations sont importantes pour la production en masse deM. anticarsiae pour le programme de lutte biologique.      

Studies on the characteristics of parasitism ofPlutella xylostella (Lep.: Plutellidae) by a larval parasiteDiadegma semiclausum (Hym.: Ichneumonidae)

Laboratory experiments were conducted to study the characteristics of parasitism of diamondback moth,Plutella xylostella (L.), a worldwide pest of crucifers, by a larval parasite,Diadegma semiclausum Hellén. Results showed that the greater the host larval density, the lesser was the percentage of larvae parasitized. The area of discovery decreased with increasing parasite density, but k-value remained practically unchanged. Parasitism reduced food consumption in parasitised larvae. No difference was observed in duration of larval instars between the parasitized and healthy larvae. As the frequency of superparasitism increased, the proportion of production of female progeny also increased. Presence of parasite larva within the host larva deterred superparasitism greater than the presence of parasite egg. Presence of larva of eitherD. semiclausum or another larval parasite,Cotesia plutellae Kurdjumov, within host larva deterred multiparasitism by either species greater than the presence of egg of either parasite species.Diadegma semiclausum was much more aggressive thanC. plutellae in parasitisingP. xylostella larvae.     

Functional response of Telenomus busseolae (Hym.: Scelionidae) an egg parasitoid of the sugarcane stem borer,Sesamia nonagrioides (Lep.: Noctuidae) at different temperatures

Telenomus busseolae Gahan is the most important egg parasitoid of sugarcane stem borers in Iran. Laboratory experiments were conducted to evaluate the functional response of T. busseolae to egg densities of Sesamia nonagrioides (Lefebvre) under four different temperatures (20, 25, 30 and 35°C). Results of logistic regression revealed a type III functional response for all temperatures tested and type of functional response was not affected by temperature. Roger's random parasite equation was fitted to observed data at 35°C. In the other data sets (collected data under 20, 25 and 30 °C) Roger's equation could not provide meaningful parameters, therefore Holling's disk equation was used to fit the data. The attack rate for T. busseolae varying from 0.001784 to 0.10704, 0.0026 to 0.152, 0.0024 to 0.144 and 0.000866 to 0.05196 per h and estimated handling times were 0.59, 0.50, 0.53 and 0.29 h at 20, 25, 30 and 35°C, respectively. Based on asymptotic 95% confidence intervals, functional response parameters did not differ significantly from 20 to 30°C, which indicates that handling time and attack rate are least affected by the temperature changes. The results suggest a similar performance of T. busseolae against S. nonagrioides eggs at temperatures of 20–30°C. These results show that T. busseolae is well adapted to temperature changes during the sugarcane growing season.     

Impact of males on the progeny sex ratio of Campoletis chlorideae (Hym., Ichneumonidae), a parasitoid of Helicoverpa armigera (Hübner) (Lep., Noctuidae)

Abstract: The endoparasitoid Campoletis chlorideae and its host Helicoverpa armigera were reared in the laboratory to determine the progeny sex ratio of C. chlorideae in the presence and absence of male parasitoids. It was observed that the presence of male parasitoids affects the progeny sex ratio by decreasing the number of females in the offspring population, i.e. a significant increase in the proportion of males was observed in united sexes. Therefore, while constructing the life table of the parasitoid, the effect of presence of male parasitoids, should be considered together with other factors, which decreases the efficiency of the parasitoid.     

Development and encapsulation of the endoparasitoid,Microplitis croceipes (Hym.: Braconidae), in six candidate host species (Lep.)

Encapsulation and development of the endoparasitoid,Microplitis croceipes (Cresson), were studied in six atypical lepidopteran host species whose usual host isHelicoverpa zea (Boddie). The candidate hosts examined were: the fall armywormSpodoptera frugiperda (J. E. Smith); the beet armyworm,Spodoptera exigua (Hübner); the cabbage looper,Trichoplusia ni (Hübner); the greater wax moth,Galleria mellonella (L.); the Indian meal moth,Plodia interpunctella (Hübner); and the diamondback moth,Plutella xylostella (L.). BothS. exigua andT. ni were completely unsuitable forM. croceipes development due to the high rate of eggs that were encapsulated within three days after parasitism. Encapsulation inS. frugiperda included mainly parasitoid eggs and was first detected six days after parasitization at 25°C and two days at 30°C. Encapsulation inG. mellonella occurred only in the larval stage of the parasitoid. InP. interpunctella, parasitoid larvae reached the 3rd stadium, but none of them pupated. OnlyS. frugiperda andG. mellonella supported successful development ofM. croceipes from egg to adult. The percentage of parasitoids reaching the adult stage in these hosts was higher at 30°C than at 25°C (13% vs. 4% inS. frugiperda, and 21% vs. 3% inG. mellonella, respectively). However, these percentages were too low to substitute them as a more economical host for rearingM. croceipes. This biological information will be useful in additional laboratory studies directed toward reducing the rate of encapsulation (e.g., manipulation of host rearing temperature) to increase production ofM. croceipes on these hosts.     

Growth-promoting effects of ecdysteroids and juvenile hormone on in vitro development of the larval endoparasitoid,Venturia canescens (Hymenoptera: Ichneumonidae)

We previously reported that lipophorin, fetal bovine serum (FBS), and 20-hydroxyecdysone (20-HE) are essential for the development of the larval endoparasitoid Venturia canescens larvae in vitro. The present study was undertaken to determine the optimal concentrations of those three substances in the MGM-450 medium, and to examine the hormonal effects of ecdysteroids and juvenile hormone (JH) on the development of the parasitoid larvae in vitro. When the culture was started with embryos at the post-germband stage, concentrations of 3 mg/ml of lipophorin and 20% of FBS were most suitable for the development of the parasitoid. The growth-promoting effect of 20-HE increased in a concentration-dependent manner and peaked at a concentration of 1 &mgr;g/ml. Excess concentration led to malformations of the larvae. Three other ecdysteroids, ecdysone, 2-deoxy-20-hydroxyecdysone, and polypodine B had the same effect, although their activity was lower than that of 20-HE. Cholesterol had no effect; most larvae failed to develop. When the medium was supplemented with JH, the duration of the developmental period was significantly shortened, but this hormone was not found to be essential.     

In vitro development of the fish parasite Hysterothylacium aduncum from the third larval stage recovered from a host to the third larval stage hatched from the egg

Anisakids are parasitic nematodes of fish worldwide, producing economic and human health concerns. It is thus important to ascertain their in vitro life cycle in laboratory studies. Here we describe the in vitro development of third-stage larvae (L3) of Hysterothylacium aduncum isolated from blue whiting Micromesistius poutassou, to the hatching of L3 from eggs obtained from H. aduncum worms grown in GLIT medium (a modified mixture of Yaeger's LIT [Liver Infusion Tryptose] and Grace's media) at pH 4.0, 13 degrees C and with 5% CO2 in air. Under these conditions, L3 recovered from fish developed to mature adults (3.4 to 6.2 cm in length), with oviposition starting from Day 26 in culture. Fertilized eggs (mean size 64 x 52 microm) had a thick, rugose eggshell and were larger than unfertilized ones (mean size 49 x 42 microm), whose eggshells were thin and smooth. Eggs laid during the first and second week of oviposition, and maintained in 2.8% NaCl solution at 13 degrees C, developed to L3. Under these maintenance conditions, between 20.6 and 52.5% of the eggs laid during the first week developed into larvae. Motile larvae, enclosed in a sheath, hatched from between 2 and 11% of these eggs. The larvae started to hatch 23 d after deposition. These larvae were 144 to 215 microm in length, enclosed in a 237 to 305 microm-long sheath. This GLIT culture medium may help to study the biology of this and other anisakids.     

Effects of lipophorin and 20-hydroxyecdysone on in vitro development of the larval endoparasitoid Venturia canescens (Hymenoptera: Ichneumonidae)

We previously reported that development of the embryos of the larval endoparasitoid Venturia canescens proceeded in the insect cell culture medium, MGM-450, and was promoted by the addition of a pupal extract from their host Galleria mellonella. The developmental promotion also was obtained by supplementing an equal amount of chicken egg yolk instead of the pupal extract to the medium. In this case, approximately 30% of the embryos developed into the second instar, but the value increased to more than 90% by treatment with 20-hydroxyecdysone. The medium supplemented with a G. mellonella pupal extract obtained by using Carlson's solution displayed growth-promoting ability, and in the extract, apolipophorin I was electrophoretically detected in large amounts. Both lipophorin purified from G. mellonella pupae and low density lipoprotein from chicken egg yolk acted as a growth-promoting substance for parasitoid development, although fetal bovine serum and 20-hydroxyecdysone were required as supplements to the medium for the expression of the ability. This indicated that lipophorin or lipophorin-transported lipids could act as a substance closely related to the growth-promoting factor(s) putatively involved in the host extract.     

Effect of host plant on parasitism ofHelicoverpa armigera (Lep.: Noctuidae) byMicroplitis demolitor (Hym.: Braconidae)

Microplitis demolitor Wilkinson is an important larval parasitoid ofHelicoverpa armigera (Hübner) andH. punctigera (Wallengren) in Australia. The effect of host plant on parasitism of second instarH. armigera byM. demolitor was investigated in a glasshouse experiment. Parasitism was low (0%) on chickpea. Moderate to high levels of parasitism (22.4% to 75.4%) were recorded on sorghum, sunflower, maize, cotton and soybean. The results suggest that releases of larval parasitoids into chickpea are unlikely to enhance parasitismlevels during the first spring generation ofHelicoverpa spp.     

Intraspecific host discrimination and larval competition inMicroplitis croceipes,Microplitis demolitor,Cotesia kazak (HYM.: Braconidae) andHyposoter didymator HYM: Ichneumonidae), parasitoids ofHeliothis virescens (LEP.: Noctuidae)

Intraspecific host discrimination and larval competition were studied forMicroplitis croceipes (Cresson),Microplitis demolitor Wilkinson,Cotesia kazak (Telenga), andHyposoter didymator (Thunberg), solitary endoparasitoids of the tobacco budworm,Heliothis virescens (F.). In ovipositional choice tests between unparasitized and parasitized hosts, the mean number of ovipositions for unparasitized hosts was significantly higher than the mean number of ovipositions for hosts parasitized once by a conspecific female forC. kazak andH. didymator, demonstrating that females of these two species discriminate against hosts recently (within a few seconds) parasitized by a conspecific female. No significant difference in oviposition occurred between these two kinds of hosts forM. croceipes andM. demolitor. Mean percent parasitization by a second conspecific female was determined at 24, 48, and 72 h delays in time between the first and second female attack, and with no delay. Except for the 0 h time delay forC. kazak andH. didymator, percent parasitization by a second conspecific female generally decreased as the delay in time between the first and second female attack increased. When the second parasitization immediately followed the first, one parasitoid larva always eliminated the other by physical combat. With a 24 or 48 h delay between the first and second parasitization, the younger larva was the victor over the older larva forM. croceipes, M. demolitor andC. kazak in at least 50% of the cases. Elimination of older larvae by younger larva was by physical attack. However, forH. didymator, the older instar was the victor, and elimination of younger larvae by older larvae was probably through physiological processes. Further, older larvae ofH. didymator apparently killed the eggs of the second female by physiological processes.      

Host preferences ofTrichogrammatoidea bactrae fumata (Hym.: Trichogrammatidae) an egg parasitoid of leafrollers (Lep.: Tortricidae)

Trichogrammatoidea bactrae fumata Nagaraja is a naturally occurring egg parasitoid of some leafrollers in New Zealand kiwifruit orchards. The parasitoid showed a distinct preference for younger host-eggs ofEpiphyas postvittana, in which it achieved a higher rate of successful development. Such a preference is not as apparent withCtenopseustis obliquana. Host-species preference experiments found that the parasitoid rarely attackedPlanotortrix octo, and successful wasp emergence from parasitised eggs of this host was low.Epiphyas postvittana was the preferred host whenT. bactrae fumata was reared on this species. When reared onC. obliquana, the parasitoid showed no preference forE. postvittana orC. obliquana.     

Improved rearing and release procedures forCotesia melanoscela (Hym.: Braconidae), an early season parasitoid ofLymantria dispar (Lep.: Lymantriidae)

Rearing and release procedures forCotesia melanoscela (Ratzeburg) (Hymenoptera: Braconidae), an early-season parasitoid ofLymantria dispar (L.), were evaluated in 1995 and 1996 at the Beltsville Agricultural Research Center, Beltsville, Maryland, USA. Mass rearing procedures were developed during the winter/spring of 1995/1996 to produce diapausingC. melanoscela cocoons for experimentation. Program efficiency as measured by percent adult emergence was estimated to be 84% with a measured sex ratio of 48:52 M:F, at an estimated cost per 1 000 cocoons of U.S. $5.26 for materials and a labor requirement of approximately 6 hours. A host larvae:female parasitoid ratio of 100:1 was found to be most efficient in terms of number of parasitoid cocoons produced per female parasitoid, but a ratio of 100:2 was most efficient in terms of number of cocoons per rearing cup. OverwinteringC. melanoscela cocoons under natural conditions for 25 weeks (November placements) before expectedL. dispar egg hatch (mid-April) resulted in excellent synchrony with host egg hatch. Alternatively, holdingC. melanoscela cocoons in cold storage for 23 or more weeks at 5°C resulted in adult parasitoid emergence beginning 10 days after removal from cold storage, and proper timing of removal would result in similar synchrony of adult emergence with host egg hatch. These alternative release strategies give managers increased program flexibility.