Schistosoma curassoni Brumpt, 1931 and S. bovis (Sonsino, 1876) in cattle in northern Nigeria

Schistosoma curassoni has been recovered from cattle in northern Nigeria. Rectal scrapings of 90 cows slaughtered at the Kano abattoir, Kano, Nigeria during March and April 1986 revealed a prevalence of 7.8% S. bovis and 2.2% S. curassoni. Further examination of the mesenteric and rectal veins of 502 cows showed that the overall prevalence of schistosomiasis was 31.1%. Local Bulinus globosus were infected successfully in the laboratory with s. bovis miracidia.     

ITS2 ribosomal RNA indicates Schistosoma hippopotami is a distinct species

The internal transcribed spacer region of the ribosomal RNA, ITS2, was sequenced from a singlé specimen of S. hippopotami collected from a pulmonary artery of the hippopotamus, Hippopotamus amphibius in South Africa. The nucleotide sequence was aligned with those of S. mansoni, S. rodhaini, S. haematobium, S. intercalatum, S. curassoni. S bovis and S. japonicum. Both maximum parsimony and genetic distance analyses were performed on these data sets. Using S. japonicum as outgroup to the African schistosomes, a single most-parsimonious tree was obtained of length 64 steps with a consistency index of 1. S. hippopotami was the sister-group to the remaining African species. This species has lateral-spined eggs and its basal position in the tree suggests that this condition is primitive and that terminal-spined eggs developed secondarily. Molecular data clearly show that S. hippopotami cannot be considered synonymous with S. mansoni. Assuming the hippopotamus is the normal host of S. hippopotami, phylogenetic analysis is consistent with an ancient association between schistosomes and ungulates.     

Observations on the infectivity and fecundity of Schistosoma curassoni from Senegal in albino mice

An average of 11% of adult Schistosoma curassoni were recovered from 200 albino mice which had been infected subcutaneously with 150-250 cercariae. Worms were primarily found in the portal veins. The average number of intrauterine eggs per female during the first 100 days p.i. was 13 and the average number of eggs produced per female worm was 103 per day for the first 60 days post oviposition. The majority of eggs were recovered from the liver (98.3%). The oograms were determined until day 95 p.i. For screening of antischistosomal drugs it is recommended not to use infections older than 60 d.p.i.     

Temperature-dependent oviposition model of Scopula subpunctaria (Lepidoptera: Geometridae)

Scopula subpunctaria, is one of important defoliating insect pests of tea plants in China. However, the effect of temperature on its longevity and fecundity had not been reported, and the temperature-dependent oviposition model is lacking. The reproductive characteristics of S. subpunctaria were investigated under eight constant temperatures (13, 16, 19, 22, 25, 28, 31, and 33℃), with a 14L: 10D photoperid and 65–85% RH. The results showed that temperature significantly influence oviposition period, longevity, and fecundity of S. subpunctaria. The mean longevity of female adults increased from 10.8 days (33℃) to 33.9 days (13℃). Male lived shorter than female did. The mean longevity of males was shortest at 33℃ (8.1 days) and longest at 23.8℃ (17.6 days). Total fecundity of S. subpunctaria females ranged from 15.4 eggs at 33℃ to 279.9 eggs at 22℃. The temperature-dependent oviposition model of S. subpunctaria was constructed based on four sub-models (developmental rate model, total fecundity model, oviposition rate model, and survival rate model). The results of this study would be helpful in forecasting and predicting population occurrence of S. subpunctaria in tea plantations.     

Experimental infection of goats with Schistosoma bovis and S. curassoni: comparative pathogenic effects

Specific mortality and morbidity have been quantified in goats experimentally infected with Schistosoma bovis or S. curassoni strains from Niger. The study involved nine animals followed during 380 days after infection with, respectively, 1,800 or 2,400 cercariae. S. bovis was significatively more pathogenic than S. curossoni in terms of mortality, weight loss and packed cell volume decrease. In addition, the intensity of clinical symptoms was significatively and positively correlated to the levels of fecal egg excretion. Compared to non-infected controls, a growth differential of, respectively, 1,600 and 880 grams per month should incite to consider S. bovis and S. curassoni as parasites of serious economical impact in sahelian countries.     

Parasitism, development and adult longevity of the egg parasitoid Telenomus nawai (Hymenoptera: Scelionidae) on the eggs of Spodoptera litura (Lepidoptera: Noctuidae)

When Telenomus nawai Ashmead or Trichogramma ostriniae Pang & Chen (Hymenoptera: Trichogrammatidae) was inoculated into intact egg masses of Spodoptera litura (Fabricius) that were covered with a scale-hair layer, T. nawai emerged from 76% of the eggs, while emergence of T. ostriniae was from only 3% of the eggs. When the hair layer was removed before inoculation, the rate by the latter increased to 21%. These observations confirmed that the hair layer effectively protects S. litura egg masses from attack by T. ostriniae, and that T. nawai parasitism is more effective. In order to assess the feasibility of T. nawai as a biological control agent for S. litura, parasitism rate, development time and adult longevity were examined in the laboratory. Emergence of T. nawai was observed in more than 95% of 0- and 1-day-old separated eggs of S. litura, but the rate decreased to 60% and 0% for 2- and 3-day-old eggs, respectively. The emergence rates of T. nawai were near 95% for temperatures in a range from 25 degrees C to 35 degrees C, but decreased to 80% at 20 degrees C. No parasitoids emerged at 15 degrees C. The developmental periods decreased as temperature increased from 20 degrees C to 35 degrees C. The developmental threshold occurred at 13.7 degrees C and 13.9 degrees C, and the effective accumulative temperatures from egg to adult emergence were 149.3 and 147.1 degree-days for females and males, respectively. Mean longevity of the adult females decreased with increasing temperature; 87.0 days at 15 degrees C and 9.5 days at 35 degrees C. The feasibility of the use of T. nawai for controlling S. litura is discussed.     

Mass rearing of the pink corn borer, Sesamia cretica Led. (Lepidoptera: Noctuidae) larvae, on semi artificial diets

The effect of two different semi-artificial diets (S.A.D1 and S.A.D2) as well as a natural corn diet on the biology and bionomics of the pink stem borer, Sesamia cretica was studied under laboratory conditions. The insect was successfully mass reared for ten successive generations at the conditions of 27 +/- 2 C degrees and 60-80% R.H. In addition, a photoperiod of 0:24 (L:D) for larvae and 12:12 (L:D) in concern to the other stages, respectively. ALong the ten successive generations, there were no significant differences between the larval periods for both the artificial diets. The S.A.D2 induced the shortest (24.0 days) larval period compared with the natural diet (27.5 days) and S.A.D1 (31.5 days). Rearing larvae on the natural diets revealed a pupal period of 11.0 days, while it was 10.0 days and 8.5 days for the artificial diets (S.A.D1) and in (S.A.D2), in respect. Moth longevity (pre-oviposition, oviposition and post-oviposition periods), to a certain extent, was affected by the larval diets. The maximal moth longevity (13.0 days) was observed for larva reared on corn plants (4, 8 and 1 days). On the other hand, the shortest period (10.5 days) of moth longevity was noticed in SAD2 (1, 9 and 0.5 days). S.A.D1 showed 11.0 days moth longevity (3,7 and 1 days). The longest oviposition period (9.0 days) was recorded in the artificial diet S.A.D2, while it was only 7.0 days in the artificial diet S.A.D1 compared with 8.0 days in case of the natural diet. The number of deposited eggs increased with the progress of the 10 successive generations (G1:G10) from 150 to 265 and from 384 eggs to 564 eggs / female for the S.A.D1 and S.A.D2, in sequence. The highest mean number of deposited eggs per female (564) was for the derived females from larvae fed on the artificial diet in G10 of S.A.D2. The rate of the deposited eggs in S.A.D2 was gradually increased (from 9.70 to 61.14% increase) more than those reared on the natural diet throughout the ten generations. The highest significant percent hatchability (92.69%) has been resulted from the artificial diet SAD2. But, it has been decreased to 85.59% in the artificial diet S.A.D1 in comparison to 65.71% in the natural diet. In addition, the significant shortest total generation period was 44.0 days resulted from the artificial diet S.A.D2, while it was 53.5 and 54.0 days for corn plants and the artificial diet S.A.D1, consequently. In short, results indicated that the S.A.D2 could be considered as a suitable artificial diet for a feasible mass rearing of the pink corn borer, Sesamia cretica led. The S.A.D2 showed the shortest larval, pupal and life span for the generation periods. Moreover, it induced the longest oviposition period and the highest mean number of deposited eggs per female and the highest significant percent of eggs hatchability/fertility. The utilization of this artificial diet (S.A.D2) would supply the researchers with high-quality insects in adequate numbers, at specified times and specific stages of development for the bioassay, toxicological and biological studies.     

Modification of the pathogenicity of Schistosoma mattheei for sheep by passage of the parasite in hamsters

Border Leicester X Suffolk sheep infected with a strain of S. mattheei maintained in hamsters do not develop the same pathological changes as Romney Marsh sheep infected with the same strain of parasite before hamster passage. To determine the cause of this reduced pathogenicity, five Romney Marsh sheep were each infected with 10 000 cercariae of the hamster-passaged parasite and five with 10 000 cercariae of a S. mattheei strain from Onderstepoort, South Africa, passaged exclusively through sheep. Striking pathological and parasitological differences were found between the two strains. Infection with the "sheep" strain was lethal, whereas infection with the "hamster" strain produced little evidence of clinical disease. By 13 weeks post-infection the mean body weight of the sheep infected with the sheep strain had declined by 15% compared with both the uninfected controls and the sheep infected with the hamster strain, and the mean PCV was lowered to 20% in the sheep strain infected animals. Egg production began at seven weeks with the sheep strain, faecal counts rising to more than 300 e.p.g., whereas only two of the sheep infected with the hamster strain passed eggs in the faeces (at nine weeks) and the maximum egg count was 50 e.p.g. Twice as many adult worms of the sheep strain were recovered, and, although the number of eggs found in the tissues "per worm pair" was not significantly different, overall egg production was higher for the sheep strain; also more of the sheep strain eggs were deposited in the intestines. Similar parasite differences were seen in a supplementary study in mice and it seemed that "attenuation" of the parasite had occurred, presumably due to its maintenance in hamsters. Histopathological observations and faecal egg counts both indicated an inability of hamster strain eggs to penetrate the intestinal lumen; this was probably important in reducing the pathogenicity of the hamster strain.     

Cross-resistance between Schistosoma mansoni and Fasciola hepatica in sheep

Five sheep were exposed to 5,000 S. mansoni cercariae percutaneously and the stools examined for 20 wk to determine patency. The sheep were found to be partially susceptible to a primary infection and showed great individual variations in their pathophysiological responses. All of the sheep acquired a patent infection with S. mansoni and eggs were first seen in feces 9 wk postexposure with no eggs detected after 14 wk. At necropsy 20 wk postexposure only dead S. mansoni worms were found. KOH digests revealed that tissue egg counts were low, ranging from 0 to 133 in the liver, and 0 to 257 in the intestine. Primary infection of sheep with S. mansoni followed by oral infection with F. hepatica metacercariae 10 wk later resulted in a reduction of 51% in F. hepatica worms recovered over controls infected with F. hepatica for 10 wk. All 5 of the S. mansoni-infected/F. hepatica-challenged sheep developed 71 or less F. hepatica worms. In contrast, 3 of the 5 F. hepatica-infected sheep developed 113-197 worms. However, although the experimental mean worm burden was lower than the control group, the variability in the control group was too great to obtain significance between the groups. There was a clear tendency toward normocytic normochromic anemia following a primary infection with S. mansoni; however, blood values were more reduced in the F. hepatica challenge controls than in the animals that received primary infection with S. mansoni.     

取食不同糖分对卵育型寄生蜂潜蝇姬小蜂雌蜂寿命和卵子发生的影响

取食糖类物质有利于延长具寄主取食特性的卵育型寄生蜂的寿命。为了明确自然界常见糖分对卵育型寄生蜂的营养功能差异, 本研究比较了取食葡萄糖、 果糖、 蔗糖、 海藻糖和松三糖5种常见糖分对斑潜蝇类害虫的优势寄生蜂潜蝇姬小蜂Diglyphus isaea雌蜂寿命和卵子发生的影响。结果显示: 取食5种糖均能显著延长雌蜂寿命（P<0.0001）; 取食果糖的雌蜂寿命显著长于取食葡萄糖、 蔗糖、 海藻糖和松三糖的雌蜂寿命（P<0.0001）, 取食葡萄糖、 蔗糖和海藻糖3个处理间差异不显著（P>0.4234）, 但均显著长于取食松三糖（P<0.0001）; 同时, 各个处理的雌蜂寿命与其个体大小均分别呈显著正相关关系。初羽化雌蜂卵巢中没有Ⅲ级卵子（即成熟卵子）; 清水处理的雌蜂, 24 h后卵巢中Ⅲ级卵子达到高峰, 48 h时则全部重吸收; 而取食5种糖的雌蜂, 卵巢中的Ⅲ级卵子和总卵子数量整体上均呈现先显著上升而后逐步下降的趋势, 取食不同糖分的雌蜂卵子形成高峰期的时间不同, 而且取食不同糖分的雌蜂间Ⅲ级卵子高峰日数量和总卵子高峰日数量均无显著差异（P>0.05）。该研究结果为潜蝇姬小蜂的大量室内饲养和田间释放提供了依据。     

Biological studies on Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae), egg parasitoid of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae)

The tomato moth, Tuta absoluta Meyrick, is one of the most important tomato pests in South America. In Argentina, management strategies include only chemical control. In this work, the parasitoid wasp Trichogrammatoidea bactrae Nagaraja was evaluated as a potential natural enemy against this pest. Biological and population parameters were estimated by developing a life table under laboratory conditions at 25 ± 1oC, 14:10 photoperiod and 60 ± 10% RH. Three cohorts of 26-30 T. bactrae females each were placed with one of the three following treatments: 1 - Sitotroga cerealella (Olivier) eggs on a piece of cardboard; 2 - S. cerealella eggs on a piece of tomato leaf, and 3- T. absoluta eggs on a piece on tomato leaf. The following parameters were estimated for each cohort: survival (egg to adult), longevity, fecundity and oviposition period of females, sex proportion of the F1, net rate of reproduction (Ro), mean generation time (T) and intrinsic rate of population increase (r m). Survival of the T. bactrae immatures was higher than 90% on both, S. cerealella and T. absoluta eggs. The female survival curves corresponded to type III and showed no significant differences among treatments. The three cohorts did not show significant differences between sex ratio, female longevity, oviposition period, fecundity and the population parameters studied. These results indicate that T. bactrae would be a potential biological control agent of T. absoluta.     

Horn growth rate and longevity: implications for natural and artificial selection in thinhorn sheep (Ovis dalli)

We used horn measurements from natural and hunted mortalities of male thinhorn sheep Ovis dalli from Yukon Territory, Canada, to examine the relationship between rapid growth early in life and longevity. We found that rapid growth was associated with reduced longevity for sheep aged 5 years and older for both the hunted and natural mortality data sets. The negative relationship between growth rate and longevity in hunted sheep can at least partially be explained by morphologically biased hunting regulations. The same trend was evident from natural mortalities from populations that were not hunted or underwent very limited hunting, suggesting a naturally imposed mortality cost directly or indirectly associated with rapid growth. Age and growth rate were both positively associated with horn size at death for both data sets, however of the two growth rate appeared to be a better predictor. Large horn size can be achieved both by individuals that grow horns rapidly and by those that have greater longevity, and the trade-off between growth rate and longevity could limit horn size evolution in this species. The similarity in the relationship between growth rate and longevity for hunted and natural mortalities suggests that horn growth rate should not respond to artificial selection. Our study highlights the need for the existence and study of protected populations to properly assess the impacts of selective harvesting.     

不同饲料对小峰熊蜂工蜂群发育的影响

糖和花粉对熊蜂的生长发育和繁殖起重要作用。本研究测定和分析了2种糖源（白砂糖、蜂蜜）和5种花粉（杏花粉、油菜花粉、向日葵花粉、玉米花粉、茶花粉）的饲料组合对小峰熊蜂Bombus hypocrita的无王工蜂群寿命、产卵前期时间、产卵量、幼虫拖出数、卵杯数、雄蜂出房时间和子代雄蜂数量的影响。结果表明： 只饲喂糖类食物时, 工蜂寿命显著短于有花粉的饲料组, 而且工蜂不产卵。含有花粉的各饲料组之间工蜂寿命存在显著差异, 饲喂玉米花粉的工蜂寿命小于其他4种花粉组。在工蜂产卵前期时间和卵杯数量方面, 10种含有花粉的饲料组之间差异不显著; 但在产卵量、幼虫拖出数、雄蜂出房时间和子代雄蜂数量等方面, 各饲料组之间差异较大。白砂糖和杏花粉组的产卵量最高; 杏花粉组和茶花粉组的幼虫拖出数量显著低于其他花粉组; 油菜花粉组和杏花粉组的雄蜂出房时间显著短于其他花粉组; 杏花粉组的子代雄蜂数量显著高于其他饲料组。结果显示不同饲料组合对小峰熊蜂工蜂群的发育影响很大。因此建议在熊蜂的人工繁育过程中, 在不同的发育阶段应给予不同的饲料配方。     

Effect of temperature on life table parameters of predatory thrips Scolothrips longicornis (Thysanoptera: Thripidae) fed on twospotted spider mites (Acari: Tetranychidae)

Environmental variables such as temperature are important factors that affect the efficiency of biological control agents. This study examined the effect of temperature on the sex ratio, longevity, oviposition periods, fecundity and life table parameters of the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), at six constant temperatures: 15, 20, 26, 30, 35, and 37 degrees C. Approximately 75% of the progeny were female, except at 37 degrees C, at which temperature the proportion of males increased. Adult longevity as well as the preoviposition, oviposition, and postoviposition periods decreased significantly with temperature. Thus, adults lived for approximately 5 wk at 15 degrees C and < 1 wk at 37 degrees C with preoviposition, oviposition, and postoviposition periods ranging from 6.4 to 0.4, 24.4-3.1, and 7-0.8 d between the two temperature extremes, respectively. The maximum (56.48 eggs) and minimum (11.69 eggs) value of total fecundity was recorded at 26 and 37 degrees C, respectively. The intrinsic rate of natural increase (r(m)) of S. longicornis increased linearly with increasing temperature from 0.056 d(-1) at 15 degrees C to 0.310 d(-1) at 35 degrees C. The lower temperature threshold for the population increase of S. longicornis was estimated to be around 5 degrees C. The data suggest that the upper temperature threshold for the predatory thrips is approximately 37 degrees C. The results showed that populations of S. longicornis are able to develop at a broad range of temperatures and that this predator is well adapted to the high temperatures that occur in the Mediterranean region.     

Parasitism capacity of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) reared under different temperatures on Bonagota salubricola (Meyrick) (Lepidoptera: Tortricidae) eggs

The parasitism capacity of Trichogramma pretiosum Riley strain bonagota on Bonagota salubricola (Meyrick) eggs was studied under the temperatures of 18, 20, 22, 25, 28, 30 and 32 degrees C. The number of days with parasitism, accumulated parasitism, total number of eggs parasitized per female and parasitoid longevity was evaluated. In the first 24h, parasitism ranged from 1.6 (32 degrees C) to 8.8 (22 degrees C) eggs of B. salubricola. Accumulated egg parasitism of B. salubricola reached 80% in 1st to 4th day at 20 degrees C to 32 degrees C, respectively, and in the 7th day at 18 degrees C. Temperatures from 18 degrees C to 22 degrees C were the best suited for the total eggs parasitized for female, resulting in 35.4 and 24.6 eggs/male respectively. T. pretiosum female longevity ranged from 7.8 to 2.5 days, at 18 degrees C and 32 degrees C, respectively. The results showed that T. pretiosum strain bonagota is better adapted to temperatures from 18 degrees C to 22 degrees C.     

Oviposition model of overwintered adult Tetranychus urticae (Acari: Tetranychidae) and mite phenology on the ground cover in apple orchards

The phenology of overwintered Tetranychus urticae was studied on the ground cover in apple orchards in the early season, and an oviposition model of overwintered adults was developed. The movement of overwintered adults from trees to ground cover started from mid-March and continued until mid-April. One life cycle from eggs to new adults (the 1st generation adults) on the ground cover was from late March to early May. The longevity and fecundity of overwintered T. urticae were affected largely by temperature. The longevity ranged from 46.6 days at 10 degrees C to 6.5 days at 35 degrees C. The total fecundity was minimum (0.2 eggs) at 10 degrees C and maximum (45.5 eggs) at 25 degrees C. The relationship between total fecundity and temperature was described well by a nonlinear equation. The cumulative age-specific oviposition rate was described well by the two-parameter Weibull function. The overall adult survival exhibited a reverse logistic curve. Three temperature-dependent components, age-specific cumulative oviposition rate, temperature-dependent total fecundity and age-specific survival rate functions, were incorporated into an oviposition model. The oviposition model simulation described the occurrence pattern of eggs laid by overwintered T. urticae on the ground cover in apple orchards relatively well.     

Influence of temperature on life-table parameters of Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae) fed on Tetranychus urticae Koch

The influence of temperature on life-table parameters, fecundity and survivorship of the predatory ladybird, Stethorus gilvifrons , fed on Tetranychus urticae was determined at seven constant temperatures of 15°C, 20°C, 25°C, 28°C, 30°C, 35°C and 40°C. No development was observed at 40°C, thus being regarded as the threshold for the development of S. gilvifrons . The results indicate a significant decrease in male and female longevity with increasing temperature from 15°C to 35°C. The longest and shortest longevity were 18.40 and 12.75 days for males and 17.40 and 8.80 days for females, respectively. The intrinsic rate of natural increase ( r _m ) and the net reproductive rate ( R ₀) of S. gilvifrons linearly increased with increasing temperatures from 15°C to 35°C, while the mean generation time ( T ) and doubling time (DT) decreased linearly within this temperature range. The highest values of r _m (0.240 females/female/day) and R ₀ (59.27 females/female) and the lowest mean generation time (17.01 days) and DT (2.88 days) were recorded at 35°C. The maximum (185.50 eggs) and minimum (25.50 eggs) measurement of total fecundity was also recorded at 35°C and 15°C, respectively. The results indicate that temperature greatly affected fecundity, survivorship and life-table parameters of S. gilvifrons , and that 35°C is a suitable temperature for population growth of this predator.     

Influence de l'alternance d'hôtes sur le développement de Tetranychus urticae Koch (Acari, Tetranychidae): conséquences sur l'infestation des agrumes au champ

Influence of host plant changing on the development of Tetranychus urticas Koch (Acari, Tetranychidae): consequence of mite infestation in Citrus fields. Changes of hosts in T. urticae is associated with notorious lost of reproduction potentialities. At 25°C, the fecundity of females which are always reared on Solanum nigram (75.7 eggs) fell to 1.07 eggs when they were reared on Citrus . It is the same for the longevity of females in this mite. The females permanently feeding on Citrus have a longevity of 16.9 days compared with only 9 days in females from Solanum nigrum that were transferred to Citrus . Similar changes operated at 20°C produce the same results. The practical consequences of these experiences on the swarming of mites in the field of Citrus were analysed.     

Oviposition of the dung beetle Aphodius ater in relation to the abundance of yellow dungfly larvae (Scatophaga stercoraria)

1. The dung beetle Aphodius ater and the yellow dungfly Scatophaga stercoraria are temporally co-occurring species in sheep dung, which they use for reproduction and nutrition ( A. ater ) or for reproduction only ( S. stercoraria ) during the spring in northern Germany. Scatophaga stercoraria uses fresh sheep dung pellets a few hours old for oviposition, whereas A. ater lays eggs into 2–10-day-old pellets. In the present study, the egg laying behaviour of A. ater in sheep dung in relation to the presence of larvae of S. stercoraria was investigated experimentally.
2. Choice experiments, based on examining the egg laying behaviour of beetles in 2- and 4-day-old pellets with and without high and low densities of fly larvae, showed the following. In 2-day-old pellets, the beetles did not distinguish between pellets without fly larvae or with fly larvae at low larval density but avoided laying eggs into pellets with a high larval density. In 4-day-old pellets, the beetles always preferred to lay their eggs into pellets without fly larvae, regardless of larval density.
3. The influence of different densities of larvae of S. stercoraria on dung depletion was examined by measuring the dry weight, organic matter content and organic nitrogen content of the remaining dung after larval development. The presence of the larvae led to a reduction in all three parameters.
4. The beetles' behaviour of laying eggs into older pellets, and their awareness of the presence of high densities of fly larvae, enables them to avoid egg laying into pellets that will have been depleted by fly larvae before the beetle larvae have finished their development.     

Longevity of Zygocotyle lunata in Balb/c mice and long-term survival of digeneans in vertebrate hosts

This study used Balb/c mice to examine the longevity of Zygocotyle lunata in a murine host. Of 11 mice, each exposed to 20 Z. lunata cysts, six were infected with a total of 12 worms from 11 to 24 weeks postinfection (PI). Live worms recovered at 24 weeks PI had a mean body area of about 25?mm2. These worms produced viable eggs with well-developed miracidia following embryonation in artificial spring water for 2 weeks at 28°C. The Balb/c mouse is a useful model to study longevity of this paramphistomid trematode for at least 6 months PI. An additional aspect of this article is a review of the pertinent literature published from 1937 to 2007 on ageing and longevity of digeneans.