Superparasitism ofEpilachna varivestis [Col.: Coccinellidae] byPediobus foveolatus [Hym.: Eulophidae]: Influence of temperature and parasitoid-host ratio

Superparasitism ofEpilachna varivestis Mulsant larvae by the hymenopterous parasitoid,Pediobius foveolatus (Crawford), occurred under laboratory conditions. However,P. foveolatus avoided previously parasitized larvae in a manner which was directly related to the number of times host larvae were initially parasitized. Increasing the parasitoid-host ratio also increased percent host mortality and highest overall host mortality occurred at 15.6°C when the parasitoid-host ratio was 10∶10. Higher temperatures (22° and 28°C) and higher parasitoid-host ratios yielded higher numbers of parasitized larvae although a significant number of parasitoids failed to emerge at the highest parasitoid-host ratio. Higher temperatures along with increasing parasitoid-host ratios favored production of more male parasitoids.     

Longevity and reproductive rate ofPatasson lameerei [Hym.: Mymaridae], a parasitoid ofSitona spp. [Col.: Curculionidae] eggs

Patasson lameerei DeBauche produced an average of 28.5 offspring under 2 temperature regimes usingSitona hispidulus (Fabricius) eggs as hosts. Although its fecundity was not affected by the temperature regimes,P. lameerei lived significantly longer at 6.7/18.3°C than at 21.1°C. When ample hosts were available,P. lameerei produced more offspring during the 1st few hours of its adult life than during any other comparable period. When the parasitoids were denied access to host eggs for 1,2, or 3 days after emergence, they still produced similar numbers of offspring during their 1st 24 h exposure to hosts.     

The biology ofLophyroplectus luteator [Hym.: Ichneumonidae] onNeodiprion sertifer [Hym.: Diprionidae] in Ontario

Adult femaleLophyroplectus luteator (Thunb.) oviposit in all feeding stages ofNeodiprion sertifer (Geoff.), although they prefer the smallest of any larvae present at a given time. Females tend to distribute eggs contagiously both within and between host feeding colonies. Eclosion of eggs does not occur until after the host has spun its cocoon. Larval development then requires approximately 1 month in the laboratory. There is an obligatory eonymphal diapause which requires a minimum of 60–80 days at 2°C to fulfil, and post-diapause development requires 3–4 weeks.     

Host discrimination byChelonus insularis [Hym.: Braconidae], telenomus heliothidis [Hym.: Scelionidae], andTrichogramma pretiosum [Hym.: Trichogrammatidae]

The ability of female parasitoids (Chelonus insularis Cresson,Telenomus heliothidis Ashmead, andTrichogramma pretiosum Riley) to distinguish between parasitized and unparasitized tobacco budworm,Heliothis virescens (F.), eggs was determined in laboratory studies. All 3 species were relatively efficient at detecting eggs that were previously parasitized by conspecific females.T. heliothidis andT. pretiosum were able to discriminate on the basis of external examination of host eggs, whereasC. insularis appeared to examine hosts internally as well as externally. In interspecific tests, no species readily rejected eggs parasitized by the other 2 species.     

Influence of temperature on the oviposition rate and longevity ofOpius concolor siculus [Hymenoptera: Braconidae]

The author has studied the influence of different temperatures (22°, 24°, 26°, 28°C) on oviposition and longevity ofOpius concolor siculus Mon., studying separately 13 couples at 22°, 15 at 24°, 100 at 26° and 11 at 28°C. The optimum temperature has been found to be 26°C. Differences have been observed betweenO. concolor Szepl. «African» andO. concolor siculus Mon. «Sicilian».     

The effects of temperature on the longevity of adultDrosophila willistoni infected withNosema kingi

The effects of various temperatures on adultDrosophila willistoni Sturtevant infected withNosema kingi Kramer were studied. The minimal and maximal temperatures for the normal development of both the host and parasite were 17±2°C and 27±2°C respectively. 22±2°C appeared to be the optimal temperature rature for rearing both the host and parasite since the life span of the flies and the parasite burden were greatest at this temperature. Generally, as the temperature increased, the life span of the adultD. willistoni decreased.     

Biology of the flea beetle,Altica carduorum [Col.: Chrysomelidae] on Canada thistle (Cirsium arvense) in South Dakota

A laboratory colony of 50 adults ofAltica carduorum Guérin-Méneville was established at South Dakota State University. Beetles reared in this colony had an average preoviposition period of 7 days when exposed to a regular cycle of 16 hr of light (24°C) and 8 hr of darkness (12.7°C). The laboratory reared females, whose longevity averaged 100 days, laid an average of 259.3±9.7 eggs. High temperatures and/or low RH are limiting factors to beetle survival. In the field eggs were laid throughout June on the underside of leaves along the edges of the veins. Adults fed throughout the summer and then over-wintered in the soil. Some of these beetles emerged the following spring and laid viable eggs. Factors limiting establishment in South Dakota, however, were high temperatures, low humidities, and the predators,Lebia viridis Say andHarpalus pennsylvanicus Degeer.A. carduorum originates from the Swiss Rhône valley where there is a relatively “continental” climate, but is limited to special habitats where comparatively high humidity occurs. South Dakota climate is characterized by cold winters, and hot, dry summers, therefore establishment would be most difficult.     

Stimulation of oviposition and successful rearing ofTelenomus heliothidis [Hym.: Scelionidae] on nonhosts by use of a host-recognition kairomone

Through use of a recognition kairomone, the parasitoidTelenomus heliothidis Ashmead is induced to oviposit and successfully develops in nonhost eggs.T. heliothidis successfully develops in the eggs ofSpodoptera frugiperda (Smith) andPhthorimaea operculella Zeller, but fails to develop in eggs ofAnthonomus grandis Boheman. Both sexes of the parasitoid are produced from the nonhosts, and development time is the same as in a natural host such asHeliothis virescens F. The use of recognition kairomones could be of great use in artificial rearing of nongeneralist parasitoids suchT. heliothidis.     

Effect oforthogalumna terebrantis [Acari: Galumnidae] on neochetina eichhorniae [col. curculionidae] eggs and oviposition

Adult waterhyacinth mites,Orthogalumna terebrantis Wallwork, did not consume eggs of the mottled waterhyacinth weevil,Neochetina eichhorniae Warner, under 4 temperature regimes (viz. 5°–25°, 10°–30°, 15°–35° and 20°–40° C). Microscopic examination showed that mites did not feed or attempt to feed on weevil eggs and they starved when weevil eggs were the only source of food. At the same temperature regimes, 0, 50, 100, 150 and 200 mites were added to aluminium pans containing 3 pairs of adult weevils and a fresh waterhyacinth pseudolamina. Weevils laid more eggs/female (P≤0.05) in the presence of mites.     

Developmental interactions between the army wormLeucania separata [Lep.: Noctuidae] and its parasiteApanteles ruficrus [Hym.: Braconidae]

The developmental interactions between the gregarious endoparasitoidApanteles ruficrus Hal. and the army worm,Leucania separata Walker were investigated. The parasitoid preferred young host larvae and developed in 9.5 days irrespective of host age at the time of parasitization. The growth of parasitized host larvae were depressed. The net maximum weight of the host larva was positively correlated with the number of parasitoid eggs laid when the 2nd instar was parasitized. And when parasitizing in 2nd instar, the weight of parasitoid was negatively correlated with the number of eggs laid. The parasitoid has an ability to regulate the size of the host and the parasitoid itself according to the number of eggs laid when the host larva is very small.     

Biology ofclausicella suturata [Dipt.: Tachinidae] a parasite ofEctomyelois ceratoniae [Lep.: Phycitidae]

The tachinid flyClausicella suturata Rondani is a solitary parasite ofEctomyelois ceratoniae (Zeller). It was grown under laboratory conditions (26±0.5°C, 55±5% R.H.) and the host-parasite relationships were studied. The different stages of the parasite were briefly described. The eggs are deposited on the carob (Ceratonia siliqua L.,Caesalpiniaceae) pods, near the openings of the host's tunnels and hatch immediately. The Ist instar maggot is directed by the web fibers of the host towards the caterpillar which is hidden in the carob pod. The parasites develop normally only in 4th and 5th instar caterpillars. The parasitized caterpillar spins its cocoon inside the carob pod before being killed by the parasite. The fully grown maggot leaves the host and pupates inside its cocoon. Adult longevity is dependent upon the presence of carbohydrate in the diet. Maximal male and female longevity (50% survival of 21 and 17.5 days respectively) was reached on a carbohydrate diet and water, at 26°C and 55% R.H. Newly emerged females readily mate with one or two-day old males. The average fecundity of a female is 202 eggs, deposited during 13.6 days, after an incubation period of 6.9 days. Superparasitism is common in nature but only one maggot is successful in completing its development.     

Interspecific competition among endoparasitoids of tobacco budworm larvae [Lep.: Noctuidae]

The ability of female larvae endoparasitoids [Microplitis croceipes Cresson:Cardiochiles nigriceps Viereck andCumpoletis sonorensis (Carlson)] to distinguish between unparasitized tobacco budworm,Heliothis virescens (F.), larvae andH. virescens larvae parasitized by the egg-larval parasitoidChelonus insularis,Cresson, was determined in laboratory studies. The 3 species of larval endoparasitoid females did not appear capable of distinguishing between unparasitized andC. insularis parasitized larvae resulting in multiple parasitoidism. The results of the ensuing competition between the 3 species for possession of the host demonstrated that bothC. sonorensis andM. croceipes were intrinsically superior toC. insularis. Both larva endoparasitoids destroyed the olderC. insularis larvae by physically attacking the latter. The presence ofC. insularis larvae in the host was found to prevent the hatch of compeatingC. nigriceps eggs through physiological suppression. The results show that the early attack of a host, as in the egg-larval parasitoid habit, is not necessarily advantageous.     

Gryon gnidus,a scelionid egg-parasite ofAcanthomia tomentosicollis [Hem.: Coreidae] in Nigeria

Gryon gnidus Nixon (Hym.: Scelionidae) is an egg-parasite of the pigeon pea coreid,Acanthomia tomentosicollis Stål in Nigeria. The life-cycle is completed in 8–14 days. The parasite is solitary and levels of parasitism in the field vary between 0% and 69%. The parasite is highly host-specific and eggs of other legume-infesting coreids includingAcanthomia horrida Germ.,Anoplocnemis curvipes F.,Mirpeurus torridus Westw., andRiptortus dentipes F. are not attacked. High levels of parasitism were recorded and parasite population build-up followed the trend of host population levels but did not prevent the host populations from reaching economic injury levels.     

Interactions betweenPleolophus basizonus andLophyroplectus luteator [Hym.: Ichneumonidae], two parasites ofNeodiprion sertifer [Hym.: Diprionidae]

Females ofPleolophus basizonus (Gray.) show a very strong avoidance of cocoonedNeodiprion sertifer (Geoff.) prepupae in which there are eggs, larvae or prepupae ofLophyroplectus luteator (Thunb.). When multiparasitism does occurP. basizonus is the successful competitor but adults are much smaller than those from hosts that were not multiparasitized.     

Characterization of a recombinant l-fucose isomerase from Caldicellulosiruptor saccharolyticus that isomerizes l-fucose, d-arabinose, d-altrose, and l-galactose

A recombinant l-fucose isomerase from Caldicellulosiruptor saccharolyticus was purified as a single 68 kDa band with an activity of 76 U mg^?1. The molecular mass of the native enzyme was 204 kDa as a trimer. The maximum activity for l-fucose isomerization was at pH 7 and 75°C in the presence of 1 mM Mn²⁺. Its half-life at 70°C was 6.1 h. For aldose substrates, the enzyme displayed activity in decreasing order for l-fucose, with a k _cat of 11,910 min^?1 and a K _m of 140 mM, d-arabinose, d-altrose, and l-galactose. These aldoses were converted to the ketoses l-fuculose, d-ribulose, d-psicose, and l-tagatose, respectively, with 24, 24, 85, 55% conversion yields after 3 h.     

Parasitization of 6 lepidopteran cotton pests byChelonus blackburni [Hym.: Braconidae]

When eggs of 6 species of lepidopteran cotton pests were offered toChelonus blackburni Cameron, all were parasitized except those of the saltmarsh caterpillar,Estigmene acrea (Drury). However, the parasite did not distinguish between parasitized and unparasitized eggs, so superparasitization was common. Of the 5 accepted species (pink bollworm,Pectinophora gossypiella (Saunders), cotton bollworm,Heliothis zea (Boddie), tobacco budworm,Heliothis virescens (F.), cabbage looper,Trichoplusia ni (Hübner), and beet armyworm,Spodoptera exigua (Hübner), pink bollworms and cotton bollworms were the most suitable hosts. When all 5 species were offered, the order of preference was as follows: pink bollworms = cabbage loopers > cotton bollworms > tobacco budworms > beet armyworms. In paired preference tests the parasite consistently preferred pink bollworms.     

Mechanical transmission of beet yellows virus toChenopodium quinoa Willd. andChenopodium foliosum (Moench) Asch.

Beet yellows virus (BYV) was mechanically transmitted by sap from sugar-beet plants, infected with BYV, to the plants ofChenopodium quinoa Willd. and ofChenopodium foliosum (Moench) Asch. Mechanical transmission of BYV to the plants ofTetragonia expansa Murr. failed. Infectious material was homogenized in phosphate buffer with veronal and EDTA, pH 7–8. Experimental plants were darkened three days before infection and kept at a temperature of 5°C. Plants ofC. quinoa Willd. were decapitated. Back transmissions fromC. quinoa Willd. andC. foliosum (Moench) Asch. infected with BYV, to sugar-beet plants were carried out by the aveidMyzus persicae Sulz. These transmissions were positive. Filamentous particles of BYV, of an average length 1275 nm, were found in plants ofC. quinoa Willd. andC. Foliosum (Moench) Asch., infected with BYV.     

A d-psicose 3-epimerase with neutral pH optimum from Clostridium bolteae for d-psicose production: cloning, expression, purification, and characterization

d-Tagatose 3-epimerase family enzymes can efficiently catalyze the epimerization of free keto-sugars, which could be used for d-psicose production from d-fructose. In previous studies, all optimum pH values of these enzymes were found to be alkaline. In this study, a d-psicose 3-epimerase (DPEase) with neutral pH optimum from Clostridium bolteae (ATCC BAA-613) was identified and characterized. The gene encoding the recombinant DPEase was cloned and expressed in Escherichia coli. In order to characterize the catalytic properties, the recombinant DPEase was purified to electrophoretic homogeneity using nickel-affinity chromatography. Ethylenediaminetetraacetic acid was shown to inhibit the enzyme activity completely; therefore, the enzyme was identified as a metalloprotein that exhibited the highest activity in the presence of Co²⁺. Although the DPEase demonstrated the most activity at a pH ranging from 6.5 to 7.5, it exhibited optimal activity at pH 7.0. The optimal temperature for the recombinant DPEase was 55 °C, and the half-life was 156 min at 55 °C. Using d-psicose as the substrate, the apparent K _m, k _cat, and catalytic efficiency (k _cat/K _m) were 27.4 mM, 49 s^?1, and 1.78 s^?1 mM^?1, respectively. Under the optimal conditions, the equilibrium ratio of d-fructose to d-psicose was 69:31. For high production of d-psicose, 216 g/L d-psicose could be produced with 28.8 % turnover yield at pH 6.5 and 55 °C. The recombinant DPEase exhibited weak-acid stability and thermostability and had a high affinity and turnover for the substrate d-fructose, indicating that the enzyme was a potential d-psicose producer for industrial production.     

Mortality factors of satin moth,Leucoma salicis [Lep.: Lymantriidae], in aspen forests in Maine

Natural control agents of the satin moth,Leucoma salicis (L.) were examined in 2Populus grandidentata Michaux stands. Highest mortality occurred in overwintering larvae, with the causal agents 2 fungi,Paecilomyces sp. andHirsutella gigantea Petch, a factor causing death symptomatic of a pathogen, the parasiteEupteromalis hemipterus (Walker) and death from unknown causes. Mortality fromPaecilomyces sp. andE. hemipterus was reduced where overwintering sites were covered with burlap cloth. Parasites recovered from larvae and pupae included the braconidsApanteles melanoscelus (Ratzeburg) andMeteorus versicolor (Wesmeal), the ichneumonidCoccygomimus pedalis (Cresson), the tachinidsCompsilura concinnata (Meigen),Carcelia laxifrons Villeneuve,Tachinomyia variata Curran, and the sarcophagidsSarcophaga aldrichi Parker andAgria housei Shewell. Larval and pupal predators included the carabidCalosoma frigidum Kirby, pentatomids, and birds, particularly black-billed cuckoos,Coccyzus erythrophthaimus (Wilson). Eggs were parasitized by the scelionidTelenomus prob.californicus Ashmead and the trichogrammidTrichogramma minutum (Riley). Predators of adult satin moths included the hermit thrush,Hylocichla guttata (Pallas), and pentatomid bugs.