Low temperature storage effects on two olive fruit fly parasitoids

Effects of cold storage temperatures and storage duration were evaluated for Psyttalia humilis (Silvestri) from Namibia and Psyttalia ponerophaga (Silvestri) from Pakistan, braconid parasitoids of Bactrocera oleae (Rossi) imported to California, USA. Immature stages of P. humilis were exposed to 4, 6, 8, 10, or 12 °C for 1, 2 or 4 months (pupa only at 4 and 12 °C) and then held at 24 °C for adult emergence. Less than 5 % of parasitoids in the 4–8 °C treatments survived, regardless of storage duration. At the 10 °C treatment, adult survival decreased with increased storage duration, but increased with advancing developmental stages. Survival was not affected at the 12 °C treatment. Adult P. humilis were exposed to 6, 8, 10 °C for short periods (1, 2, 4, or 6 weeks) or ambient winter conditions in Parlier, California, USA (about 9 °C). Regardless of storage temperature, P. humilis reproduction was reduced after storage of four and six weeks. Similarly, after 4 months at ambient winter temperatures, P. humilis reproduction was reduced. Psyttalia ponerophaga pupae stored at 6 °C for 41–97 days had decreased survival and increased developmental time. Survival of P. ponerophaga pupae ranged from 13.9–52.1 %, whereas under similar storage conditions survival of P. humilis was <0.7 %, suggesting P. ponerophaga is more cold tolerant than P. humilis.     

Comparative evaluation of two olive fruit fly parasitoids under varying abiotic conditions

Psyttalia lounsburyi (Silvestri) and P. humilis (Silvestri) (Hymenoptera: Braconidae) were evaluated in California for their potential to control the invasive olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Psyttalia lounsburyi is a specialist on B. oleae while P. humilis also attacks other tephritid species. Field cage trials, conducted from 2006 to 2009, were used to compare P. lounsburyi and two populations of P. humilis (Kenya and Namibia) in California’s interior valley and coastal regions. Both parasitoid species reproduced on B. oleae in all trials. Under similar abiotic conditions, offspring production per female was higher in P. humilis than in P. lounsburyi, suggesting that host specificity by P. lounsburyi does not confer a higher efficiency on B. oleae in cultivated olives. Two abiotic factors were shown to impact parasitoid efficiency. First, adult parasitoid survival was poor during periods of high summer temperatures, common to the olive production areas in California’s interior valleys. Second, parasitism levels were lower on B. oleae larvae feeding in larger Ascolano cv. fruit than in smaller Manzanillo cv. fruit. Results are discussed relative to biological control of B. oleae in commercial olives and the usefulness of natural enemies specialized to attack fruit flies in wild olives compared with the larger cultivated olive fruit.     

Effect of temperature on immature development and longevity of two introduced opiine parasitoids on Bactrocera invadens

Temperature‐dependent development, parasitism and longevity of the braconid parasitoids, Fopius arisanus Sonan and Diachasmimorpha longicaudata Ashmed on Bactorcera invadens Drew Tsuruta & White, was evaluated across five constant temperatures (15, 20, 25, 30 and 35°C). Developmental rate decreased linearly with increasing temperature for both the parasitoid species. Linear and Brière‐2 nonlinear models were used to determine the lower temperature threshold at which the developmental rate (1/D) approached zero. For F. arisanus, lower thresholds to complete development estimated with the linear and nonlinear models were 10.1 and 6.9°C, respectively. The total degree‐days (DD) required to complete the development estimated by the linear model for F. arisanus was 360. In D. longicaudata, the linear and nonlinear models estimated lower thresholds of 10.4 and 7.3°C, respectively, and the total DD estimated was 282. In F. arisanus, percentage parasitism differed significantly across all temperatures tested and was highest at 25°C (71.1 ± 2.5) and lowest at 15°C (46.4 ± 1.4). Parasitoid progeny sex ratio was female biased at all temperatures except at 20°C. In D. longicaudata, percentage parasitism was highest at 20°C (52.2 ± 4.0) and lowest at 15°C (27.7 ± 2.5). Parasitoid progeny sex ratio was female biased and similar for all temperatures. Adult longevity of both parasitoids was shortest at 35°C and longest at 15°C, and females lived significantly longer than males at all temperatures tested. Our findings provide some guidance for future mass rearing and field releases of the two parasitoids for the management of B. invadens in Africa.     

Effect of the presence of olive fruit on ovarian maturation in the olive fruit fly, Dacus oleae, under laboratory conditions

Ovarian maturation was prevented in 7-, 22-, 23- and 28-day-old females of Dacus oleae (Gmelin) (Diptera: Tephritidae), developed in the pre-imaginal stages at LD 12:12, 19±1°C and kept as adults at LD 16:8, 26±1°C without access to olive fruits. In females of the above ages having continuous access to olive fruits and held under the same photoperiod and temperature conditions, 54, 87 and 100%, respectively, had mature oocytes. When the females had access to domes of paraffin wax, the percentages of females with mature oocytes were intermediate between those with and those without access to olive fruits. Under the above photoperiod and temperature conditions unfavorable for maturation, 50% of 4-week-old females had mature oocytes if exposed for one week to olive fruits during their first week and 91% if exposed during their 4th week of adult life. The respective percentages with wax domes in the cages were again intermediate between those with olives and those without olives or wax domes. The presence of olive fruits had also a strong positive effect on the ovarian maturation of females which developed from egg through the adult stage at LD 16:8, 26±1°C, a condition favoring ovarian maturation. Access to wax domes had again an intermediate effect on maturation. It is concluded therefore that the lack of ovarian maturation of D. oleae females which is observed under a short photophase during the pre-imaginal stages if followed by a long photophase and an increase of temperature during the adult stage, continues at least till the end of the 4th week of adult life in the absence of olive fruits but is averted when such fruits are offered to the adult flies.

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Résumé La maturation ovarienne des femelles adultes agées de 7, 22–23 et 28 jours de D. oleae ayant accompli leur développement embryonnaire, larvaire et nymphal en LD 12:12, 19±1°C et maintenues en LD 16:8, 26±1°C, sans accès à des olives, est inhibée. Dans les mêmes conditions, mais avec accès permanent à des olives, 54% des femelles ont des ovocytes mûrs à 7 jours, 87% à 22–23 jours et 100% à 28 jours. Avec des femelles ayant accès à des domes de paraffine, les pourcentages d'individus ayant des ovocytes mûrs sont intermédiaires entre ceux des deux situations précédentes. Dans les conditions cidessus défavorables à la maturation ovarienne, 50% des femelles de 28 jours ont des ovocytes mûrs si elles sont en présence d'olives durant leur première semaine de vie imaginale et 91% si elles sont en présence la 4éme semaine. Les pourcentages respectifs concernant les femelles pourvues de dômes de paraffine sont encore intermédiaires entre ceux des femelles avec olives et ceux de femelles privées de tout substrat. La présence d'olives a aussi un effet fortement positif sur la maturation ovarienne de femelles ayant accompli leur développement pre-imaginal et maintenues aussi à l'etat adulte en conditions LD 16:8, 26±1°C, favorisant la maturation ovarienne. L'accès à des dômes de paraffine a, là encore, un effet intermédiaire. On conclut par conséquent que la non maturation ovarienne des femelles de D. oleae qui est causée par une photopériode à jour court pendant la vie pre-imaginale accompagné par une photopériode à jour long et une augmentation de la température pendant la vie imaginale persiste au moins jusqu'à la fin de la quatrième semaine de la vie imaginale en absence d'olives, mais ne se produit pas si on met les femelles adultes en présence d'olives.

     

The effect of different dietary sugars and honey on longevity and fecundity in two hyperparasitoid wasps

In nature adult insects, such as parasitic wasps or 'parasitoids' often depend on supplemental nutritional sources, such as sugars and other carbohydrates, to maximize their life-expectancy and reproductive potential. These food resources are commonly obtained from animal secretions or plant exudates, including honeydew, fruit juices and both floral and extra-floral nectar. In addition to exogenous sources of nutrition, adult parasitoids obtain endogenous sources from their hosts through 'host-feeding' behavior, whereby blood is imbibed from the host. Resources obtained from the host contain lipids, proteins and sugars that are assumed to enhance longevity and/or fecundity. Here we conducted an experiment exploring the effects of naturally occurring sugars on longevity and fecundity in the solitary hyperparasitoids, Lysibia nana and Gelis agilis. Although both species are closely related, L. nana does not host-feed whereas G. agilis does. In a separate experiment, we compared reproduction and longevity in G. agilis reared on either honey, a honey-sugar 'mimic', and glucose. Reproductive success and longevity in both hyperparasitoids varied significantly when fed on different sugars. However, only mannose- and water-fed wasps performed significantly more poorly than wasps fed on four other sugar types. G. agilis females fed honey produced twice as many progeny as those reared on the honey-sugar mimic or on glucose, whereas female longevity was only reduced on the mimic mixture. This result shows not only that host feeding influences reproductive success in G. agilis, but also that non-sugar constituents in honey do. The importance of non-sugar nutrients in honey on parasitoid reproduction is discussed.     

Intrinsic inter-specific competition in a guild of tephritid fruit fly parasitoids: Effect of co-evolutionary history on competitive superiority

Tephritid fruit fly parasitoid guilds are dominated by solitary koinobiont species that attack different host stages, but most emerge as adults from host puparia. Previous studies suggest intrinsic competitive superiority by the egg-attacking parasitoid Fopius arisanus (Sonan) against all larval-attacking parasitoids in Hawaii. In this study, we tested the early-acting competitive superiority prediction in relation to the co-evolutionary history of competition between an egg–larval parasitoid (Fopius ceratitivorus Wharton), and each of three larval parasitoids [Psyttalia concolor (Szépligeti), Diachasmimorpha kraussii (Fullaway), and Diachasmimorpha longicaudata (Ashmead)]. F. ceratitivorus and P. concolor share a common origin (eastern Africa), while D. kraussii is an Australian species, and D. longicaudata is from Southeast Asia. The outcomes of intrinsic competition between the egg-attacking parasitoid and each of the three larval-attacking parasitoids within their common host, the Mediterranean fruit fly Ceratitis capitata (Wiedemann) were compared. F. ceratitivorus invariably eliminated the co-evolved P. concolor through physiological suppression of the later-attacking parasitoid’s egg development, providing evidence that supports the early-acting-superiority hypothesis. However, F. ceratitivorus was unable to suppress development of the two non co-evolved larval parasitoids. Instead, the larvae of both later-acting parasitoid species physically killed F. ceratitivorus larvae inside the host. The results suggest that co-evolutionary history influences competitive superiority. The evolution of inter-specific competition and its implications for biological control are discussed.     

Effect of larval host food substrate on egg load dynamics, egg size and adult female size in four species of braconid fruit fly (Diptera: Tephritidae) parasitoids

Life history theory predicts that individuals will allocate resources to different traits so as to maximize overall fitness. Because conditions experienced during early development can have strong downstream effects on adult phenotype and fitness, we investigated how four species of synovigenic, larval-pupal parasitoids that vary sharply in their degree of specialization (niche breadth) and life history (Diachasmimorpha longicaudata, Doryctobracon crawfordi, Opius hirtus and Utetes anastrephae), allocate resources acquired during the larval stage towards adult reproduction. Parasitoid larvae developed in a single host species reared on four different substrates that differed in quality. We measured parasitoid egg load at the moment of emergence and at 24 h, egg numbers over time, egg size, and also adult size. We predicted that across species the most specialized would have a lower capacity to respond to changes in host substrate quality than wasps with a broad host range, and that within species, females that emerged from hosts that developed in better quality substrates would have the most resources to invest in reproduction. Consistent with our predictions, the more specialized parasitoids were less plastic in some responses to host diet than the more generalist. However, patterns of egg load and size were variable across species. In general, there was a remarkable degree of reproductive effort-allocation constancy within parasitoid species. This may reflect more “time-limited” rather than “egg-limited” foraging strategies where the most expensive component of reproductive success is to locate and handle patchily-distributed and fruit-sequestered hosts. If so, egg costs, independent of degree of specialization, are relatively trivial and sufficient resources are available in fly larvae stemming from all of the substrates tested.     

饵料淀粉水平对饥饿后日本沼虾生长代谢的影响

研究了饵料淀粉水平对饥饿后日本沼虾生长代谢的影响,探讨营养水平对日本沼虾补偿生长的作用.结果表明,在4 d饥饿后,饵料中20%、25%的淀粉水平能使日本沼虾达到完全补偿生长,机体代谢率高于对照组,而8 d的饥饿处理,各组日本沼虾的生长代谢均低于对照组,说明饥饿时间及恢复投喂后饵料淀粉水平对日本沼虾补偿生长有一定的影响.     

The dynamics of ovarian maturation and oocyte resorption in the Queensland fruit fly, Dacus tryoni, in daily-rhythmic and constant temperature regimes

The rate of oocyte development in constant regimes corresponded to the rates predicted by Pritchard's (1970) relationship which indicates that the lower temperature threshold is 13.5dgC. Rates in fluctuating regimes indicated that development occurs at certain temperatures below the constant threshold if these are alternated with higher temperatures on a daily basis
In certain fluctuating regimes, oocyte development occurred at a rate in excess of 3.5% per day and maturation proceeded to completion. In such regimes resorption occurred only if egg laying was prevented; when this happened the terminal oocytes usually remained intact and the penultimate ones were resorbed. In other fluctuating regimes, oocyte development proceeded at a rate of less than 3.5% per day and no maturation was achieved because the most advanced oocytes were resorbed-either before or during the vitellogenic phase.
The 3.5% threshold corresponds to a value of 2 day-degrees per day (2DDPD) above 13.5C. Resorption, but no development, was observed in partly mature flies around O DDPD, whereas neither occurred in a still colder regime. These results are shown to be in accord with Fletcher's (1975) field data which are also used to discuss the significance of resorption. Finally, the DDPD relationship is used to define those daily temperature profiles which may permit maturation in the field.     

Exceptional longevity in the tephritid, Ceratitis rosa, a close relative of the Mediterranean fruit fly

This study shows that the fruit fly, Ceratitis rosa (Karsch), has a significantly longer life span than the medfly, C. capitata (Wiedemann); the species used as a model organism for the demographics of insect aging. This was somewhat surprising given that both have similar distributions and overlapping niches. We postulate that the greater longevity of C. rosa is related to the fact that it can occupy colder habitats where the availability of suitable host plants may be very unpredictable in both time and space.     

Effects of dietary carbohydrate on cholesterol metabolism in rats and rabbits.

Semipurified diets produce a marked hypercholesterolemia in rabbits and tend to elevate the level of plasma cholesterol in rats. They also decrease rates of oxidation of [26-14C]cholesterol to respiratory 14CO2 and excretion of label in fecal lipid, compared with commercial feed. In both species, the hypercholesterolemia was prevented and the rate of oxidation of [26-14C]cholesterol increased by using unmodified potato starch as the carbohydrate component of the semipurified diets. Potato starch was poorly digested by rats but appeared to be well utilized by rabbits. A semipurifed diet containing cooked potato starch gave results in rats comparable to those obtained with diets containing other types of carbohydrate. Cooked potato starch produced diarrhea in rabbits, thus complicating interpretation of the results. When the diarrhea was treated with antibiotics, the results were similar to those obtained with other carbohydrates. Rats fed commercial diet which had been heated in an oven or autoclaved had higher plasma levels than those fed untreated commercial diet but no significant differences in rates of oxidation or excretion of cholesterol were observed.     

Differences in regulation of carbohydrate metabolism during early fruit development between domesticated tomato and two wild relatives

Early development and growth of fruit in the domesticated tomato Solanum lycopersicum cultivar Money Maker and two of its wild relatives, S. peruvianum LA0385 and S. habrochaites LA1777, were studied. Although small differences exist, the processes involved and the sequence of events in fruit development are similar in all three species. The growth of developing fruits is exponential and the relative growth rate accelerates from 5 days after pollination (DAP 5) to DAP 8, followed by a decline during further development. Growth is positively correlated to the standard “Brix plus starch’’ in the period DAP 8–DAP 20. Carbohydrate composition and levels of sugars and organic acids differ in fruits of the wild accessions compared to domesticated tomato. The wild accessions accumulate sucrose instead of glucose and fructose, and ripe fruits contain higher levels of malate and citrate. The enzymes responsible for the accumulation of glucose and fructose in domesticated tomatoes are soluble invertase and sucrose synthase. The regulation of initial carbohydrate metabolism in the domesticated tomato differs from that in the wild species, as could be concluded from measuring activities of enzymes involved in primary carbohydrate metabolism. Furthermore, changes in the activity of several enzymes, e.g., cell wall invertase, soluble invertase, fructokinase and phosphoglucomutase, could be attributed to changes in gene expression level. For other enzymes, additional control mechanisms play a role in the developing tomato fruits. Localization by in-situ activity staining of enzymes showed comparable results for fruits of domesticated tomato and the wild accessions. However, in the pericarp of S. peruvianum, less activity staining of phosphogluco-isomerase, phosphoglucomutase and UDP-glucosepyrophosphorylase was observed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

负荷时间和类型对糖代谢,脂肪供谢,蛋白质代谢的影响

２５名运动员在相同的时间里随３种不同类型的负荷和不同的时间里承受相同的负荷,测定负荷后血浆ＴＣＡ循环产物,ＦＦＡ组成和尿液尿素氮,尿肌酐,游离氨基酸组分含量。结果表明：同一时间里采用运动量相近但类型不同的负荷,会产生不同的生理效应,同一负荷内容安排在下午比安排在早晨或上午更容易导致人体内蛋白质分解代谢加强;耐力负荷以早晨训练对ＴＣＡ循环和ＦＦＡ及其组分影响较大;下午训练利于发展速度,力量等项目的素     

Effect of dodeconium on carbohydrate metabolism

It is shown in experiments on albino rats that dodeconium in therapeutic doses stimulates the glycolytic processes and inhibits the aerobic oxidation of glucose in the pentose phosphate cycle as well as the final stages of gluconeogenesis. Such an action of dodeconim leads to hypoglycemia and normalizes many indices of carbohydrate metabolism in alloxane diabetes.