Studies ontrichogramma buesi as a biocontrol agent againstPieris rapae in Egypt

Trichogramma buesi was reared in the laboratory on eggs of the Mediterranean flour moth,Anagasta kuehniella. The incubation period of the parasite's egg was 27 h at 23 °C and 22 h at 27 °C. The larval stage lasted 3.6 and 3.2 days, the pre-pupa lasted 16 and 23 h, and the pupa lasted 5.4 and 4.6 days at 23° and 27°C, respectively. The total developmental time (from egg to adult) averaged 9.2, 9.4, and 9.1 days when the parasite was reared on eggs ofPieris rapae, Spodoptera littoralis, andA. kuehniella, respectively, at 27 °C. Sex ratio inT. buesi was 1 ♂: 1 ♀ in nature and 1 ♂: 1.3 ♀ in the laboratory. The daily and total numbers or progeny produced/female were 5.1 and 98.2 adults, respectively. The parasite female, fed on honey, lived 10.7 days at 27 °C and 12.1 days at 23 °C. Percentages of parasitism byT. buesi on eggs ofP. rapae collected from cabbage fields ranged between 0 and 31.5 % in 1985 and betwcen 0 and 36.4% in 1986 during July through December. The respective figures on eggs collected from turnip fields were 16–42.2% and 12.5–32.1% during November and December.      

Biological studies withChrysocharis parksi [Hym.: Eulophidae] a parasite ofLiriomyza spp. [Dipt.: Agromyzidae]

Biological studies withChrysocharis parksi Crawford, a parasite of agromyzid leafminers, were conducted.C. parksi successfully parasitized the following species in the genusLiriomyza Mik.,L. huidobrensis (Blanchard),L. sativae Blanchard,L. trifolii (Burgess), andL. trifoliearum Spencer. Successful parasite development was recorded from 8 plant families and 16 genera. Host plants which were suitable for leafminer development to the adult stage were also suitable for parasite development. Mean immature developmental period (egg to adult, usingL. trifolii as the host) at 21.1°, 26.7°, and 32.2° C was (for both sexes) 23, 14, and 14 days, respectively. Longevity of females provided only water was inversely related to temperature; significantly longer survival occurred at 21.1° C (5.0 days) compared to 26.7° C and 32.2° C (3.2 and 2.1 days, respectively). The addition of honey to the diet significantly improved longevity of both sexes at all temperatures. Adult female parasites which were provided an average of 33.0L. trifolii larvae per day produced an average of 135 offspring at a constant 26.7° C.C. parksi host-fed on ca. 3.7 leafminer larvae per day over an 11-day adult lifespan.      

Instars ofMicroplitis rufiventris [Hym.: Braconidae] and their relative developmental speed under different photoperiods

The internal parasiteMicroplitis rufiventris Kok. passes through 3 instars but moults 3 times within its host. The last moult occuring just at emergence time. The morphology of the egg and larval stages of the parasite are discussed. At 27°C and a photoperiod of 6 h (6L:18D) the endo-developmental cycle of the parasite can summarize as follows: Egg 18–24 h; instar 1,4 days (fighting phase 48 h; feeding phase 30–48 h); instar 2, 12–18 h and instar 3,3 days. The effect of different photoperiods on the relative speeds of the endo-developmental stages of the parasite at each of 30, 25, 20°C were carefully studied. At the first 2 temperatures, the short photoperiod (6L:18D) accelerated the development of larval instars, while both of 18L:6D or 0L:24D slowed down the development. Under the latter photoperiods some larvae failed to moult and had emergence problems. The influence of photoperiod is significantly noticeable at 20°C. The incubation period of the egg-stage was prolonged significantly at 18L:6D and the development of larval instars was significantly faster and refined at 6L:18D. The factor(s) inhibiting the development of the egg-stage perhaps differ from those affecting the larval development. The ventral area of the host mid-gut among malpighian tubes seems to be where the surplus parasite larvae are eliminated by physical attack. A physiologically suppressed parasite larva is able to attack its developed competitor of the same age. Teratocytes cells perhaps play a part in eliminating the surplus parasite larvae by physiological suppression.     

Diapause induction in the thrips predatorAmblyseius cucumeris [Acarina: phytoseiidae] under greenhouse conditions

The predatory miteAmblyseius cucumeris (Oudemans) is an important biological control agent for thrips in commercial greenhouses, but its effectiveness in fall and winter is limited by reproductive diapause induced under short day conditions. Influence of photoperiod and temperature on diapause induction was investigated to provide information for successful management of the predator. Under 8∶16 (L∶D) photoperiods and 22°C photophase temperatures, diapause incidence was inversely related to scotophase temperature, decreasing from 100% diapause at 15°C to no diapause at 21°C. In continuous darkness, diapause was induced by thermoperiods of 20∶10 and 22∶17 and 22∶17 but not 25∶15°C (T∶C) (8h thermophase). Critical daylength for inducing diapause under 22∶17°C (T∶C) was 12.45 h, which was consistent with the trend in diapause incidence in mites collected from an established greenhouse population September to November. MostA. cucumeris diapaused only when exposed to diapause inducing conditions throughout their juvenile development and none stopped laying eggs when transferred from nondiapause to diapause inducing conditions as adults. After 14 generations of genetic selection for a nondiapause strain, diapause incidence was 33.3%.      

Role of photoperiod and temperature in the induction of overwintering pupal diapause in the spotted tentiform leafminer,Phyllonorycter blancardella

The role of photoperiod and temperature in the induction of overwintering diapause inPhyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae) was examined in the laboratory and field using leafminers from commercial apple orchards in Ontario, Canada.P. blancardella exhibited a long-day response to photoperiod: long daylengths resulted in uninterrupted development whereas short daylengths induced diapause. The estimated critical photoperiod for diapause induction was L14.25∶D9.75. The larvae of leafminers destined to enter diapause took ca. 3× longer to complete development than the larvae of non-diapausing leafminers. The development prolonging effect of photoperiod decreased with decreasing daylength. Temperature modified the diapause inducing effect of photoperiod. At L14.25∶D9.75, diapause incidence was similar at 15 and 20°C but was lower at 25°C. Photoperiod also altered the normal relationship between development rate and temperature. At L14.25∶D9.75, the duration of larval development of diapausing leafminers was similar at 15, 20 and 25°C. Temperature alone is unlikely to have a role in the induction of diapause because leafminers exposed to natural late summer and fall temperature regimes and L16∶D8 did not enter diapause.     

Biology ofMicroplitis mediator [Hym.: Braconidae] a gregarious endoparasite ofAgrotis segetum [Lep.: Noctuidae]

Microplitis mediator (Haliday) a gregarious endoparasite was recorded for the first time fromAgrotis segetum (Schiff) in Ankara, Turkey. The female parasites found their hosts by responding to the faeces of the caterpillars. An average, females laid 15.5±1.6 eggs in the bodies of their hosts. The newly laid eggs were elongated, oval in shape and 0.23±0.004 mm long and 0.07 mm wide. They hatched in 5, 4 and 3 days at 20±2°C, 25±2°C and 30±2°C respectively when maintained at 60–70% R.H. and 14∶10 light∶dark regime. At the same temperatures, the larval stage lasted for 24.9±0.6, 18.2±0.4 and 17.1±0.5 days respectively. The prepupal stage was completed in 2 days at 25±2°C, whereas the prepupal and pupal (cocoon) stage lasted 10.9±0.2, 7.0±0.1 and 6.2±0.1 days respectively at the temperatures mentioned above. The adults started mating and feeding shortly after emergence. Female parasites started laying after one day, 7–11 hours and 5–7 hours at the temperatures stated above. At these temperatures females lived for 10.8±0.2, 5.4±0.1, 4.6±0.1 days and laid on average 556, 484 and 363 eggs respectively, whereas the males survived 10.5±0.3, 4.7±0.1 and 4.4±0.1 days respectively.      

Influence of diet and photoperiod on development and reproduction of European populations of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

The current study examines the effect of photoperiod (16:08 or 12:12 h L:D) and diet (eggs of Ephestia kuehniella Zeller (Lepidoptera: Phycitidae) or the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae)) on the development and reproduction of the multicoloured Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). A long-term laboratory population of H. axyridis (since 1998) and a melanic and non-melanic population originating from field collected individuals of H. axyridis in Belgium were used in this study. Long day conditions (16 h photoperiod) shortened development of the field populations with 2–3 days when compared with short day conditions (12 h photoperiod). Oviposition in the field populations was delayed by 1–3 months when reared at a 12 h photoperiod. Dissections indicated that the females were in reproductive diapause. As compared with live pea aphids, a diet consisting of E. kuehniella eggs yielded heavier adult body weights (up to 12%) and increased the number of egg laying days (by 45–169%) for both field populations at a 16 h photoperiod and lengthened adult life span (by 45–92%) under both light regimens. The morph types differed in their response to the foods offered in terms of developmental rate, pre-oviposition period and number of oviposition days. The laboratory and field strains responded differentially to regimens of food and photoperiod. The study indicated a greater nutritional plasticity of the non-melanic morphs which may offer them a competitive advantage that may in part explain the predominance of non-melanic morphs in newly colonized areas.     

Influence of breeding conditions on longevity and fecundity ofRaphitelus maculatus [Hym.: Pteromalidae] reared under standard laboratory conditions

The rearing ofRaphitelus maculatus Walker, which oviposits through the bark onto beetle larvae has been carry out under standard laboratory conditions of 22 ± 2°C, 60% R.H. and photoperiod 16L∶8D. The host (Phloeotribus scarabaeoides Bernard) has been reared by cutting fresh branches of living olive tree on which they overwinter as adults. The effect of several rearing conditions (feeding conditions) on longevity and fecundity has been tested. The time of parasitoid and host development as well as the periods of emergence from the infested cut branches has been determined. It has been noted that both longevity and fecundity are influenced by the feeding conditions, reaching toca. double value when parasitoids were fully fed. Under standard rearing conditionsR. maculatus completes its life cycle in 17–18 days depending on sex, whereasP. scarabaeoides takes about 48 days. Finally 3 emergence periods has been observed from which the 1^st is the most important and the 3^rd is always the less significantly one, provided that the emerging brood cannot oviposits easier than the parents due to a decrease on host larvae proportion as well as on parasitoid fecundity.      

Survival of the mosquito predator,Notonecta unifasciata[Hemiptera: Notonectidae] embryos at low thermal gradients

Notonecta unifasciata Guerin eggs maintained at different stages of embryonic development in water at variable temperatures (2.2–25.6 °C) and for periods of 4–12 weeks revealed maximum viability (>80 %) at the highest temperature. However, optimum nondevelopmental viability was at 14.4 °C with eight-day-old embryos (>35 %). Short term (4 weeks) storage at 14.4 °C significantly increased egg viability. Survival was poor (<20 %) at the 2 lowest temperatures. Eggs held at 14.4 °C for 12 weeks and sustainingca. 50 % mortality, may be a practical procedure for biological control.      

The effect of host age ofLymantria dispar larvae [Lep.: Lymantriidae] on the development ofGlyptapanteles liparidis [Hym.: Braconidae]

The endoparasitic development ofG. liparidis was examined in 3 different host stages of gypsy moth larvae. Hatching ofG. liparidis-larvae occurred 3 to 5 days after oviposition in hosts parasitized during their premoulting period, and after 5 to 7 days in those parasitized in the 3^rd midinstar state. The parasites generally moulted to the 2^nd larval instar between the 11^th and 13^th day in the first group, and between the 13^th and 15^th day in the latter, when they had reached a volume of 0.04–0.05 mm³. The positive correlation between host ecdysis and the ecdysis of 1^st stadium larvae to L₂ suggested that host moulting influenced the development of the parasitoid larvae. Emergence from the host larvae occurred at 20°C after 27 days on average, and coincided with the parasites moulting to the 3^rd instar. Five to 7 days after spinning their cocoons near the developmentally arrested host larva, the male, and 1 to 2 days later the female wasps eclosed. Due to the variation in the number of parasites per host, no difference was observed between the hosts parasitized at various stages; however, a tendency for later parasitized hosts to contain more parasite larvae was evident. The nutritional conditions of the moth parental generation influenced both host and parasite development. On the other hand no influence of host age was observed on emergence dates of larvae and wasps.      

Effect of temperature on the development, fecundity, progeny sex ratio and life-table of Campoletis chlorideae, an endolarval parasitoid of the pod borer, Helicoverpa armigera

Development, survival, fecundity, progeny sex ratio (PSR) and age-specific life-table parameters of the parasitoid Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) were examined at six different constant temperatures (12, 17, 22, 27, 32 and 37°C) in the laboratory [70 ± 10% RH and 10:14 h (light:dark) photoperiod]. Second instar larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) were reared on chickpea (Cicer arietinum L.) and used as the host. Development times shortened as the temperature increased from 12 to 37°C. The estimated lower developmental threshold (tL) was 3.4°C. The thermal summation for total immature stages was 379.97 degree-days. A reciprocal relationship between temperature and longevity was observed in the range of 12–17°C. The maximum mortality of pupae (71.8%) occurred at 37°C. At 22°C, the yield of a female parasitoid averaged 137.3 ± 14.7 (mean ± SD) progeny, of which 89.6 ± 7.6 were daughters. The number of daughters produced decreased when the females were kept either above or below 22°C, although the PSR was female biased in the range of 17–27°C. The analyses of life-table parameters, developmental rates, reproduction, mortality and PSR suggest that maximum population growth (r _m ) is near 27°C. There was little variation observed in most of the desired qualities of C. chlorideae in the range of 17–27°C, and it appears that the parasitoid is adapted to a wide range of temperatures. We suggest that for maximum production the parasitoid should be reared at 22 ± 4°C and be released in areas where the temperature ranges between 17° and 27°C, as in the plains of northern India.     

Influences of Culture Temperature on the Growth, Lipid Content and Fatty Acid Composition of Aurantiochytrium sp. Strain mh0186

The growth, lipid content, and fatty acid composition of Aurantiochytrium sp. strain mh0186 at different temperatures were investigated. Strain mh0186 grew well at 15–30°C, but weakly at 10°C. The biomass at 15–30°C was significantly higher than at 10 and 35°C, and the total lipid at 15–35°C was significantly higher than that at 10°C. The amount of DHA in the total fatty acid was highest at 10°C and decreased in response to temperature increase. The content of DHA (mg/g-dry cell weight) at 15–30°C were significantly higher than those at 35°C and those at 15–25°C were significantly higher than those at 10 and 35°C. The DHA yield at 15–35°C was significantly higher than those at 10 and 35°C. Unsaturation of fatty acid was regulated by temperature and was enhanced in response to temperature decrease. The ratio of DHA to DPA varied at different temperatures.     

Effect of temperature on the development of the immature stages ofBembidion lampros [Coleoptera: Carabidae]

The effects of temperature on survival and development of immature stages ofBembidion lampros were examined under controlled conditions in the laboratory. The duration of development was examined at 5°C, 12°C, 17°C, 19°C, 22°C, 25°C, 30°C and 32°C and found to be inversely related to temperature. Between 12°C and 30°C there was a significant difference in duration of egg development, but no significant difference in percentage of eggs hatched. The upper and lower lethal limits for egg development were estimated (c 31°C and 4°C respectively). There are 3 larval instars and one pupal stage. Development of larva plus pupa required a minimum of 20.9 days at 30°C. Between 22°C and 30°C survival from larva to the adult stage was 80%.      

Induction and termination of diapause inOrius predatory bugs

Photoperiodic induction of reproductive diapause at 18°C was investigated in fourOrius [Heteroptera: Anthocoridae] species.Orius insidiosus (Say) displayed a long-day response with a critical photoperiod between L11:D13 and L12:D12. Diapause in this species was terminated rapidly when the temperature and/or the daylength were increased.Orius majusculus (Reuter) also displayed a long-day response. The critical photoperiod fell between L14:D10 and L16:D8. Diapause in this species was not terminated within 14 days when both temperature and daylength were increased. InOrius albidipennis (Reuter) no diapause could be induced at photoperiods varying from L8:D16 to L16:D8. InOrius tristicolor (White) a high proportion of diapause was found at all photoperiods tested. The effect of temperature on photoperiodic induction of diapause was studied inO. insidiosus at L10:D14. Diapause occurred at 18°C, 21°C and 25°C, but not at 30°C. Again, diapause was terminated rapidly after transfer to 25°C/L16:D8. Exposing only the nymphal instars 1–5 to short daylength was not enough to induce diapause in the whole population ofO. majusculus. Orius predatory bugs are used as biocontrol agents against western flower thrips,Frankliniella occidentalis (Pergande) [Thysanoptera: Thripidael, in greenhouses. The consequences of photoperiodic induction of diapause for the success of early season releases ofOrius are discussed.     

Laboratory studies on the biology ofSpalangia nigra [Hym.: Pteromalidae]

At 21 °C,Spalangia nigra Latreille (Hymenoptera: Pteromalidae) averaged 29.3 days between exposure and emergence of 1^st progeny from host house flies,Musca domestica L. (Diptera: Muscidae). At 27 °C, the average developmental time to 1^st emergence was reduced to 26.6 days, and a majority of adult wasps emerged from host house fly puparia between 29 and 40 days postoviposition. The sex ratio of progeny ranged from 1.4 to 1.8 female-to-male, but all progeny of virgin females were male. Male wasps lived from 6.8–15 and females 11–17.8 days at 27 °C; honey as a food source increased longevity. No significant differences in parasitism byS. nigra were associated with host house fly pupal densities ranging from 1 to 200 pupae per female-male pair of wasps, but average percent parasitism decreased at host densities greater than 50. House fly pupae exposed to parasitism at ages ranging from 4 to 96 h did not differ in subsequent production of adult flies.S. nigra did not demonstrate preference for house flies or stable flies,Stomoxys calcitrans (L.) (Diptera: Muscidae) as hosts. The results of these studies indicate thatS. nigra may contribute significantly to previously unexplained mortality of house flies and stable flies.      

Effect of temperature on development and survival ofPristhesancus plagipennis [Hem.: Reduviidae]

The effect of temperature on the rate of development ofPristhesancus plagipennis Walker was determined by rearing individuals under a range of constant temperatures (22.5–35°C). Rates of development changed in a linear fashion from 22.5–30°C. Estimates of lower developmental thresholds were obtained for egg (13.1°C), nymphal (15.5°C) and egg to adult development (15.4°C). Fastest rates of nymphal and egg development occurred at 30 and 32.5°C, respectively. A requirement of 845.7 DD (degree days) was estimated for development from egg to adult. Nymphal survivorship was highest between 25 and 30°C.

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Résumé L'effet de la température sur la vitesse de développement dePristhesancus plagipennis a été déterminé par élevage des insectes dans une gamme de températures constantes allant de 22,5 à 35°C. La vitesse de développment est une fonction linéaire de la température entre 22,5 et 30°C. Le seuil théorique de développement a été estimé à 13,1°C pour l'œuf, 15,5°C pour la nymphe et 15,4°C pour le développement larvaire. Les plus grandes vitesses de développement de l'œuf et de la larve ont été obtenues respectivement à 30 et 32,5°C. 845,7 degrés-jours sont nécessaires pour le développement de l'œuf à l'adulte. La survie des nymphes a été la plus élevée entre 25 et 30°C.

     

Effect of temperature on the life history of <Emphasis Type="Italic">Eretmocerus</Emphasis> sp. nr. <Emphasis Type="Italic">furuhashii</Emphasis>, a parasitoid of <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae) is an indigenous parasitoid of Bemisia tabaci (Gennadius)(Hemiptera: Aleyrodidae) from southern China; the effects of constant temperatures on the life history of E. sp. nr. furuhashii were examined in the laboratory. The developmental period ranged from 39.2 days at 20°C to 12.40 days at 32°C. A total of 263.4 degree-days were required to complete development with a lower developmental threshold temperature of 11.1°C. Of the eggs produced, 59.3% completed development at 20°C with completion increasing to 71.5% at 26°C. Adult female longevity was 10.8 days at 20°C and 5.2 days at 32°C while the mean daily offspring reproduced per female was highest at 29°C with 5.9 offspring. Adult oviposition peaked three days after emergence at 26, 29 and 32°C, and four days post-emergence at 20°C and 23°C. The total numbers of offspring produced per female ranged from 25.7 individuals at 32°C to 41.1 individuals at 20°C. The sex ratio had a female bias and ranged from 0.72 at 17°C to 0.51 at 35°C. The intrinsic rate of increase was 0.1727 at 29°C followed with 0.1606 at 32°C. Results indicated that E. sp. nr. furuhashii reaches its maximum biological potential at temperatures ranging from 26°C to 32°C.     

Effects of extreme changes of sea water temperature and salinity on the development of the sand dollar <Emphasis Type="Italic">Scaphechinus mirabilis</Emphasis>

The combined effects of temperatures of 14, 17, 20, 22, and 25°C and salinities of 36–12‰ on embryos and larvae of the sand dollar Scaphechinus mirabilis was studied. Embryonic development is the most sensitive stage in the early ontogenesis of S. mirabilis. It is completed at a temperature of 14–20°C in a salinity range of 36–24‰ and at temperature of 22°C to 26‰. The fertilization proceeds in wider ranges of temperature and salinity. Among the swimming larvae, blastulae showed the greatest resistance to variations of these environmental factors. All the larvae survived at a temperature of 14–22°C and a salinity of 36–20‰, and more than 70% of them at 18‰. The pluteus I is the most vulnerable stage; probably this is related to the formation of the larval skeleton and transition to phytoplankton feeding. The survival of larvae at the age of 20 days was 100% at 14–22° C and a salinity of 36–24‰, most of them survived at 14–20°C and a salinity 18‰. The temperature 25 ° C is the most damaging for early development of S. mirabilis. The duration of development of that species lasts 28.5–29 days at 20°C and a salinity of 32.2–32.6‰. At 20 and 22°C, the larvae settled and completed metamorphosis more quickly if sand from the parental habitat was present. The larvae did not settle during the experiment (14 days) at 14 ° C and in the absence of sand.     

Temperature requirements of the chrysanthemum leaf miner,Chromatomyla syngenesiae [Dipt.: Agromyzidae], and its ectoparasitoid,Diglyphus isaea [Hym.: Eulophidae]

The development rate from egg to adult for ♂ and ♀Chromatomyia (Phytomyza) syngenesiae andDiglyphus isaea increased linearly between 19 and 25°C.D. isaea had a faster developmental rate thanC. syngenesiae between 19 and 25°C but therer was no difference at 16°C. FemaleD. isaea required 154.6 D° above the theoretical threshold of 12.80°C and maleD. isaea 152.4 D° above 12.9°C for total development from egg to adult emergence. FemaleC. syngenesiae needed 207.0 D° above 12°C and ♂ and 211.0 D° above 11.6°C for total development.      

Studies on the oviposition and longevity ofIlione albiseta [Dipt.: Sciomyzidae] — Potential biological control agent of liver fluke

The effect of 5 constant temperatures (10, 14, 17, 20 and 23°C) on the oviposition and longevity ofIlione albiseta was investigated. Most eggs were laid at 14–17°C and mean oviposition period declined progressively above and below 14°C. There was no significant difference between oviposition rates or preoviposition periods at each constant temperature, but the mean number of days between egg laying for each female was significantly greater at 10 °C than at 17, 20 and 23 °C than at 20 °C. The percentage of infertile eggs laid ranged from 9.2% at 23 °C to 17.9 % at 20 °C and these eggs tended to be laid at the beginning and end of each oviposition period. A possible association between sex ratio of the emergent adult and temperature is also discussed.