Use of learned visual cues during habitat location by Brachymeria intermedia

Like many other parasitoids, Brachymeria intermedia (Hymenoptera: Chalcididae) uses olfactory cues to find its host, but in addition it appears to use learned visual cues to focus its searching efforts at the macrohabitat level. In laboratory experiments, females were held in cages where Lymantria dispar pupae were hidden either in a vertical, tree-like structure or on the floor. After four days females had learned to search for hosts in the structure in which they previously had found pupae. Such training was reversible. During similar tests in a semi-natural situation, in which pupae were hung from a tree trunk or were hidden under leaf litter, females also tailored their subsequent searching to favour the macrohabitat where hosts previously had been found. This parasitoid most likely uses a combination of visual and olfactory cues during host searching.     

In Vitro Rearing of the Parasitoid Exorista larvarum (L.) (Diptera: Tachinidae) on Meat Homogenate-Based Diets

The tachinid Exorista larvarum (L.), a polyphagous gregarious larval endoparasitoid of Lepidoptera, was reared from egg to fecund adult on media containing commercial meat homogenates for babies as the main ingredient. Four media, each containing a diverse homogenate supplemented with extract of Galleria mellonella L. pupae, were tested first. Despite the difference in nutrient content, the kind of homogenate did not significantly affect the adult yields (30.2 to 40.7%) or puparial weights. Two other diets free of host materials (I and II) were then tested. Both were based on Gerber veal homogenate combined with different amounts of yeast extract and chicken egg yolk and were supplemented with wheat germ (I) or saccharose (II). Adult yields (28.7 to 32.7%) and puparial weights did not differ significantly between the two diets. Fly longevity and fecundity of the females obtained on diet I were comparable to those of the females emerged from puparia formed in G. mellonella larvae. Male and female puparial weights were, however, higher and development times longer on the diet than in the host.     

Liver-based artificial diets for the production of Orius laevigatus

Different meat- and liver-based artificialdiets were designed for the generalist predatorOrius laevigatus (Fieber) (Anthocoridae)and their suitability was compared to that ofits factitious food, Ephestia kuehniellaZeller (Pyralidae) eggs. The quality of thefood was measured by its ability to promotegrowth and oviposition of the insect. Nymphaldevelopment was slower on artificial diets thanon the control food, taking 15.0–15.9 days vs.14.3 days, respectively. Survival of nymphs fedartificial diets varied from 68.0–92.5%,compared with 96% for those fed E. kuehniella eggs. Adult weights were, however,not affected by diet. Fecundity of femalesprovided with liver diets was similar to orsomewhat lower than that of females fed Ephestia eggs. Oviposition rate and egg hatchwere similar on all diets tested. The resultssuggest that beef liver was the most importantcomponent of the diets tested, offering theessential nutrients to sustain growth andreproduction of O. laevigatus.Supplementing ingredients, like ground beef,egg yolk, sucrose and vitamin C can improve thenutritional value of the diet for O.laevigatus, but effects are rather small.Artificial diets containing liver and egg yolkas the main components may prove useful to makemass production of O. laevigatus andother heteropteran predators more cost effective.     

Influence of experience on the sequential and temporal organization of host-acceptance behavior inBrachymeria intermedia (Chalcididae), an endoparasitoid of gypsy moth

Experienced Brachymeria intermediafemales are almost twice as likely to accept a Lymantria disparpupa as inexperienced parasitoids. The sequence of parasitoid behaviors that leads to host acceptance is highly canalized. Experienced parasitoids, however, have a higher probability of initiating host investigation and making a transition from drumming to grasping, which in turn almost invariably leads to ovipositor insertion. Experienced females found the host more quickly than inexperienced females. Host-handling time did not change with experience but was longer in females that accepted rather than rejected the host. Females exposed to gypsy moth odor but not contacting pupae behaved similarly to females that never experienced host-related stimuli.     

In vitro rearing of Eucelatoria bryani: improvements and evaluation of factors affecting efficiency

In vitro rearing of Eucelatoria bryani Sabrosky (Diptera: Tachinidae) was made more efficient and economical. Absorbent cotton, used as a support to replace more expensive agar in an artificial medium, produced yields of adults equal to those reared on the agar-based medium. The weights of pupae from the cotton-supported medium were about 16% lighter than were the weights of pupae from the agar-based medium. Evaluation of diet volumes (100, 200 and 250 l) for individually reared flies revealed that highest adult yields (46.3%) were obtained when 200 l per maggot of agar-based diet were used in each well of microtiter plates; this is equivalent to 2,315 adults per liter of diet. The tachinids were small and the sizes were equal to those obtained when 10–15 maggots parasitize a single host. Costs could not be reduced by deleting free amino acids from the medium fed to older maggots because free amino acids are essential dietary ingredients for third instars of E. bryani.     

Rearing of a coleopterous predator,Trogossita japonica (Col.: Trogossitidae), on artificial diets

Artificial diets for a coleopterous predator of pine bark and wood borers,Trogossita japonica Reitter (Col.: Trogossitidae) were studied. Diets composed of silkworm pupa-powder, dry yeasts, sucrose, peptone, squid liver oil, agar and distilled water supported larval development. The size of diet-reared adults was smaller than that in the control but they mated and oviposited normally when maintained on prey insects. An aseptic rearing method for the larvae of predator, that required a single diet change, was devised.

---

Résumé Nous avons élaboré et évalué quatre milieux semi-synthétiques pour l'élevage deTrogossita japonica Reitter, prédateur d'insectes sous-corticaux et xylophages des pins. Les larves ont été nourries avec des milieux composés de poudre de chrysalide du ver à soie, levure de bière séchée, sucrose, peptone, huile de foie de seiche, agar et eau distillée. Les adultes obtenus ont été plus petits que ceux du lot témoin, mais ils se sont accouplés et ont pondu normalement quand ils ont été nourris avec des proies-insectes. Une méthode d'élevage des larves sur milieu aseptique a été élaborée, laquelle ne nécessite qu'un changement de milieu nutritionnel au cours du développement larvaire du prédateur.

     

Growth of Corbicula fluminea (bivalvia) fed artificial and algal diets

Laboratory experiments were conducted to assess the growth of Corbicula fluminea Müller (1774) fed mixed diets of the green alga Ankistrodesmus and five artificial foods (nine-grain cereal, rice flour, rye bran, denatured brewer's yeast and Ralston Purina trout chow). Clams lost weight after 30 days on each artificial diet; however, weight losses were significantly less than those of control clams which were not fed (p < 0.05). In contrast, clam growth was positive in each treatment which included Ankistrodesmus. There was no significant difference in the tissue growth of clams fed on an Ankistrodesmus monoculture and Ankistrodesmus supplemented with each artificial diet (p > 0.2). Therefore, we conclude that all of the artificial diets evaluated were of nutritional value. However, the alga Ankistrodesmus appears to be a superior food item. In subsequent experiments, clams were fed on diets consisting of various combinations of six genera of green algae (Pedinomonas, Ankistrodesmus, Chlamydomonas, Chlorella, Scenedesmus, and Selenastrum). All trialgal combinations of Chlamydomonas, Chlorella, Scenedesmus, and Ankistrodesmus and a dialgal culture of Chlamydomonas and Chlorella resulted in strong positive tissue growth. No other dialgal or monoalgal culture resulted in similar growth. Cultures of Selenastrum were found to be toxic, and their filtrate was determined to inhibit Corbicula filtration.     

In vitro rearing of Edovum puttleri, an egg parasitoid of the Colorado potato beetle, from egg to pupal stage in artificial diets devoid of insect sources: Effects of dietary amino acid and carbohydrate levels

Previous studies have demonstrated that Edovum puttleri, an egg parasitoid of the Colorado potato beetle, can be reared through the pupal stage in an artificial diet containing either hemolymph from Manduca sexta or CPB embryonic cell line-conditioned medium. In order to improve the diet and reduce production costs, i.e., eliminate the insect-derived components, the effects of 13 amino acids and 20 carbohydrates on the growth and development of the parasitoid were determined. In the presence of any one of five of the amino acids (arginine, glutamine, lysine, threonine and valine) at a concentration of 1%, or eight of the carbohydrates (cellobiose, fructose, gentiobiose, glucose, lactose, melinbiose, sorbitol and threhalose), also at a concentration of 1%, more than 75% of the larvae molted to the second instar. At higher concentrations (2 and 3%), all five of the amino acids and most of the eight sugars promoted third instar formation. Prepupal formation was also observed. In the presence of threonine (at 2 and 3%) or glutamine (at 3%), between 22 and 29% of the parasitoids formed prepupae. Of the six sugars (at 3%) that promoted prepupal formation, lactose and sorbitol which promoted 18 and 20% prepupation, respectively, were the most effective. In the presence of all 13 amino acids (each at 3%) or all 20 carbohydrates (each at 3%), 36 and 39%, respectively, of the parasitoids formed prepupae. At lower concentrations, reduced percentages of prepupal formation were observed. Since the amino acids, glutamine and threonine, and the sugars, fructose, gentiobiose, glucose, lactose, sorbitol and trehalose, when added individually to the diet (at a concentration of 3%) were most effective in promoting prepupal formation, the effect of one of these two amino acids in combination with each of the six sugars was tested. Glutamine in combination with lactose or sorbitol was able to promote pupation (6.3%), and threonine in combination with any one of five of the sugars (lactose and sorbitol were most effective) supported pupal formation (6.7%). Our study demonstrated that E. puttleri can be successfully reared from the egg through the pupal stage in an artificial diet devoid of insect materials.     

Suitability ofDacus dorsalis andCeratitis capitata [Diptera: Tephritidae] as hosts of the parasitoid,Biosteres arisanus [Hymenoptera: Braconidae]

Biosteres arinsanus (Sonan) (=B. oophilus Fullaway) showed a strong preference forDacus dorsalis Hendel overCeratitis capitata (Wiedemann) in choice tests using papaya fruits infested with eggs of both hosts in laboratory studies. In laboratory and field studiesD. dorsalis was the most suitable host. A total of 13,871 parasitoids was produced fromD. dorsalis infested fruits compared with 2,772 fromC. capitata infested fruits.      

New techniques of rearingAnagrus flaveolus [Hym.: Mymaridae], an egg parasitoid of the brown planthopper

A small cage was designed to study the biology and behavior ofAnagrus flaveolus Waterhouse, an important egg parasitoid of the brown planthopper,Nilaparvata lugens (Stal), a pest of rice. A method of rearing moderate numbers of parasitoids on planthopper eggs in the laboratory was developed. Though the mymaridAnagrus flaveolus Waterhouse, a common egg parasitoid of rice planthoppers and leafhoppers all over Asia, reduces pest populations, its biological control potential has largely been overlooked because of its minute size and the lack of suitable techniques to study and rear it in the laboratory.Ôtake (1968, 1969) described some techniques to study the development, longevity and fecundity of a related speciesAnagrus nr.flaveolus Waterhouse. The cages described herein are much simpler to build and more efficient to use compared with those developed earlier. Rearing this important parasitoid in large numbers in the laboratory has not been done before.     

Effect of ovipositional stimulants and diets on the growth and development of Trichogramma pretiosum in vitro

Ovipositional stimulants and diets were tested in vitro using several rearing methods to determine effects on the growth and development of Trichogramma pretiosum Riley. Highest yields of pupae were obtained when Manduca sexta (L.) hemolymph was added to a chicken egg yolk and milk diet. However, this hemolymph based diet (BD) produced low yields (6–7%) of adults. When a similar diet containing 20% M. sexta egg liquid (BDE) was used, the yields of adults increased 7–13 fold to as high as 75.9%. For T. pretiosum reared on the BDE diet in microtiter plates, the adult yields were 46.9 and 63.6%, respectively, when the ovipositional stimulants were either the KCl-MgSO₄ solution or the BDE diet. Thus, the harmful effects of the salt oviposition solution were significant but perhaps not so great as to prevent the use of this technique for in vitro mass production of T. pretiosum. Although the ovipositional salt solution reduced adult yields, the effect was much smaller than the nutritional or physiological effect of deleting M. sexta egg liquid from the diet.

---

Résumé Une faible production de nymphes de Trichogramma pretiosum Riley a été obtenue quand le substrat alimentaire était de l'hémolymphe de Manduca sexta L. Un régime (BD) comprenant de l'hémolymphe, du jaune d'oeuf et du lait a donné une bonne production de nymphes mais une faible production d'adultes. L'addition de 20% de contenu d'oeufs de M. sexta en régime BD a donné jusqu'à 75,9% d'adultes. Quand l'exposition des oeufs de T. pretiosum a une solution stimulant la ponte (0,68% KCl, 0,60% MgSO₄, 7H₂O) a dépassé 6 h à 27°C, la survie des oeufs a été sérieusement affectée. Des expositions plus courtes ont été indispensables au succès de l'élevage in vitro; cependant l'exposition aux solutions salines a réduit la production d'adultes. Cet effet a été partiellement maîtrisé par l'addition du contenu d'oeufs au régime artificiel. Les effets négatifs de la solution saline ont été faibles en comparaison de la saisissante augmentation de la production d'adultes due à l'addition du contenu d'oeufs de M. sexta au régime à base d'hémolymphe (BD). Nous en concluons (1) que la présence de constituants des oeufs de l'hôte dans les régimes artificiels a provoqué les productions élevées indiquées par les autres auteurs utilisant des régimes à base d'hémolymphe; (2) que T. pretiosum et T. dendrolimi Matsumura ont des besoins nutritifs différents puisque d'autres auteurs ont obtenu des productions élevées de T. dendrolimi adultes avec des régimes alimentaires privés d'extraits d'oeufs. Sur les trois techniques d'élevage in vitro utilisées, la méthode dite de goutte multiple a donné les productions de nymphes et d'adultes de T. pretiosum les plus élevées et présente plusiers autres avantages significatifs. La production de masse in vitro de T. pretiosum dépend maintenant de l'identification et de la synthèse des facteurs de croissance contenus dans l'hémolymphe et les oeufs.

     

Host regulation by the aphid parasitoid Aphidius ervi: the role of teratocytes

The biochemical profile and metabolism of Acyrthosiphon pisum(Harris) (Homoptera, Aphididae) are markedly altered and redirected in response to parasitization by the endophagous braconid Aphidius erviHaliday (Hymenoptera, Braconidae). In the present study, the role played in the host regulation process by teratocytes, cells deriving from the dissociation of the embryonic membrane of the parasitoid, is taken into consideration. The protein synthesis activity of these cells of embryonic origin is analysed in vitroand an essential characterization of those proteins de novosynthesized and released in the incubation medium is provided. Teratocytes, obtained by dissecting parasitized host aphids, 3, 4 and 5 days after parasitoid oviposition, were incubated in vitroand, at the end of the incubation period, were separated from the medium for SDS-PAGE analysis of both cellular and secreted proteins. Various cellular proteins were more abundant as the time between parasitization and teratocyte collection increased. Furthermore, two proteins, showing an approximate molecular mass of 15 kD (p15) and 45 kD (p45) respectively, were abundantly secreted in the incubation medium by 5 day-old teratocytes. Incubations in presence of ³⁵S radiolabelled amino acids indicated that p15 and p45 are both synthesized by A. erviteratocytes. The amino acid composition of these two proteins was similar to that reported for other insect proteins with a demonstrated nutritional function. The p45 protein was found to be glycosylated. A tentative physiological model describing the host regulation role played by different parasitoid-derived factors is proposed.     

In vitro culture of the egg parasitoid Telenomus heliothidis: the role of teratocytes and medium consumption in development

The solitary egg parasitoid Telenomus heliothidis Ashmead (Hymenoptera: Scelionidae) was reared from egg to adult in vitro. Both sexes of adults emerged, mated, and the females produced viable offspring in the natural host, Heliothis virescens F. (Lepidoptera: Noctuidae). While the rearing, wasp fitness was influenced by other factors. The presence of teratocytes influenced parasitoid survival and development. In addition, the quantity of medium ingested by larvae affected the survival, xize, longevity, and fecundity of adults.

---

Résumé L'oeuf isolé parasitoid Telenomus heliothidis (Hymenoptera: Scelionidae) a été obtenu d'un oeuf a un adulte in vitro. Les deux sexes adultes ont surgi, se sont accouplés et les femelles ont reprodui des progeniture viables du milieu naturel, Heliothis virescens (Lepidoptera: Noctuidae). Pendant que le milieu d'élevage etait important dans l'élevage, le bien être de la guèpe a été influence par d'autres facteurs. La présence de tératocytes a influence la survivance et le developpement de la parasite. De plus, la quantité du milieu absorbée par la varve a affecté la survivance, le developpement et la longevité, et la fecondité des adultes.

     

Egg production and survival of the citrus red mite on an artificial feeding system

An artificial feeding system was developed for the citrus red mite, Panonychus citri McGregor (Acari: Tetranychidae) to determine egg production and survival of adult female mites in response to various nutrient solutions. Egg production increased with increasing sugar concentration up to 20%, then declined. Autoclaved sodium caseinate was the most suitable nitrogen source examined, and egg production was highest on diet fractions containing 8% sodium caseinate, the highest concentration examined. Fecundity was higher when dietary nitrogen was provided entirely by protein than in whole or in part by free amino acids. Results are qualitatively similar to studies with Tetranychus urticae Koch, however optimal concentrations of major nutrients were ca. 4 to 10 times higher for P. citri than for T. urticae.

---

Résumé Une méthode d'alimentation sur diète artificielle a été mise au point pour l'acarien du citrus, Panonychus citri Mc Gregor (Acari: Tetranychidae) et a été utilisée pour déterminer l'influence de différentes solutions nutritives sur la fécondité et la survie des femelles adultes. La fécondité augmente avec la teneur en sucre jusqu'à une concentration maximale de 30%, et décline ensuite pour des concentrations supérieures. Du caséinate de sodium autoclavé s'est révélé être la meilleure source d'azote et la fécondité a été la plus forte sur des milieux contenant 8% de caséinate de sodium, concentration la plus élevée testée. La fécondité est plus grande lorsque l'azote alimentaire est fourni entièrement sous forme de protéine plutôt que sous forme d'acides aminés libres, en tout ou en partie. Les résultats sont qualitativement semblables à ceux obtenus précédemment chez Tetranychus urticae Koch, cependant les concentrations optimales des nutriments majeurs sont environ 4 à 10 fois plus élevées pour P. citri que pour T. urticae.

     

Effects of two artificial diets on the development and reproduction of Tirathaba rufivena (Walker) (Lepidoptera: Pyralidae)

Growth, survival, fecundity, and nutrition of Tirathaba rufivena (Walker) fed on two artificial and one natural diet were studied at 29±1°C and 75±5% relative humidity. Larvae reared on the two artificial diets showed faster growth and development, higher pupal survival and weight, and higher adult fecundity than those reared on a natural diet of young coconuts, Cocos nucifera L. The relative growth rate, efficiency of ingested food conversion, and efficiency of digested food conversion in larvae fed on artificial diets were significantly higher than those of larvae fed on young coconuts. The relative consumption rate of larvae fed on artificial diets was significantly lower than that of larvae fed on young coconuts. T. rufivena showed no significant degradation in ability to propagate after being reared on the artificial diet for five successive generations. These results indicated that two artificial diets are suitable for mass rearing of T. rufivena.     

Cultivation of teratocytes of the egg parasitoid telenomus heliothidis (hymenoptera: Scelionidae)

Summary A method for in vitro cultivation of teratocytes from the egg parasitoidTelenomus heliothidis (Hymenoptera: Scelionidae) is described. Parasitoid eggs, from which teratocytes were derived, were collected from 24-h-oldHeliothis virescens (Lepidoptera: Noctuidae) eggs previously parasitized byT. heliothidis females. Optimal culture conditions, including species and concentration of serum, were determined experimentally. Thirty percentManduca sexta hemolymph or 10% chicken serum in Hink’s TNH-FH medium were found to generate the most satisfactory number of teratocytes per parasitoid larva. Teratocytes cultivated in vitro showed similar development and morphology to those produced in vivo. However, cultured teratocytes lived approximately 10 times longer than teratocytes in natural hosts and were not dependent upon the presence of the parasitoid larva for normal development.     

Continuous rearing of the maize stem borerBusseola fusca on an artificial diet

Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is a major pest of maize and sorghum in many countries of tropical Africa. Hitherto, research on this important pest has been hampered by the occurrence of a six-month long diapause in the last larval stage and the lack of an artificial diet for rearing the insect in the laboratory. Incorporating 4 to 8-week-old sorghum powder in a nutritionally adequate diet and rearing larvae individually in vials at ambient laboratory conditions (25–30°C, 50–80% r.h., and L12: D12) have made it possible to rear 15 successive non-diapausing generations ofB. fusca capable of producing between 35 to 40 healthy pupae/litre of diet and upto 70% pupation without loss of vigour or reproductive capacity. Five to six generations were completed per year and the overall mean developmental period (egg-egg) was 68 days (egg 6, larval 45, pre-pupal 1, pupal 14 and pre-oviposition 2 days). Larval period lasted 70 days in the first generation compared to 32.3 days in the fifteenth generation. Average fecundity increased from 158.0 to 394.6 eggs per female with a concomitant increase of egg hatch from 44.8 to 79.6% in the first and fifteenth generation, respectively.     

In vitro rearing of Edovum puttleri,an egg parasitoid of the Colorado potato beetle,on artificial diets: Effects of insect cell line‐conditioned medium

Effects of conditioned media prepared from cell lines derived from 11 insect species (six families, three orders) on the in vitro growth and development of the egg parasitoid Edovum puttleri were investigated. The parasitoid exhibited significantly different responses to the various insect cell line‐conditioned media that were incorporated into the artificial diets. When cell lines were derived from embryos, higher percentages of 3rd instars and prepupae were observed than when cell lines were derived from fat body or ovaries. Medium conditioned with cell line IPLB‐CPB2 derived from the embryos of the Colorado potato beetle produced the best result. Preconditioning time was important. In general, 5 days of preconditioning appeared to be optimal. The growth‐ and development‐promoting effect may have resulted from growth factors or growth‐supporting factors produced/ released by the insect cell lines into the culture medium. Upon storage at 0–4°C for 7–14 days, the ability of cell line‐conditioned medium to promote development beyond the second instar was greatly reduced (approximately 10–55%). Our studies demonstrated that to support the in vitro growth and development of E. puttleri, insect hemolymph could be successfully replaced with insect cell line‐conditioned medium. These findings should facilitate the development of a cost‐effective mass‐rearing system for E. puttleri and/or other parasitoids. Arch. Insect Biochem. Physiol. 40:173–182, 1999. Published 1999 Wiley‐Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.