Feeding behaviour of Glossina pallidipes and g. morsitans centralis on Boran cattle infected with trypanosoma congolense or T. vivax under laboratory conditions

In field studies, tsetse flies (Diptera: Glossinidae) feed more successfully on cattle infected with Trypanosoma congolense Broden (Kinetoplastida: Trypanosomatidae) than on cattle infected with T. vivax Ziemann or uninfected cattle. Here we describe the first laboratory investigation of this phenomenon. In the first experiment, caged Glossina pallidipes Austen were fed for 1 and 5 min on a Boran steer infected with T. congolense clone IL 1180 and on an uninfected steer. Feeding success was recorded in this way five times over several weeks. The same protocol was subsequently used in three additional experiments with the following combinations: G. pallidipes and a steer infected with T. vivax stock IL 3913, G. morsitans centralis Machado and a steer infected with T. congolense, and G. morsitans centralis and a steer infected with T. vivax. The four experiments were replicated once, making eight experiments in total. In three experiments there was increased tsetse feeding success, measured at 1 min, after a steer became infected (T. congolense, two experiments and T. vivax, one experiment). Analysis of all data combined found no significant differences in tsetse feeding success on the different groups of cattle prior to infection, but after infection tsetse feeding success was significantly greater on the infected cattle (P< 0.001). Trypanosoma congolense infection led to a greater increase in tsetse feeding success than T. vivax infection. The increase in feeding success was not related to changes in the level of anaemia, skin surface temperature or parasitaemia. A possible explanation is the effects of trypanosome infection on cutaneous vasodilation and/or blood clotting in infected cattle. When allowed to feed for 5 min, nearly all tsetse engorged successfully and effects of cattle infection on feeding success were not found.     

Suppressive action of Samorin on the cyclical development of pathogenic trypanosomes in Glossina morsitans centralis

Male Glossina sexually sterilized by gamma-irradiation are as efficient vectors of trypanosomiasis as fertile males. An attempt was made, using isometamidium chloride (Samorin), to interfere with the cyclical development of trypanosomes in sterile males, destined for use in the sterile insect release (SIR) method of tsetse eradication. The infection rate with mature Trypanosoma congolense Broden was effectively reduced in sterile male Glossina morsitans centralis Machado, when the flies were fed on an infected goat 2 days after they were fed as tenerals on an in vitro bloodmeal containing 8 micrograms Samorin/ml blood. The infection rates with mature T.vivax Ziemann and T.brucei brucei Plimmer & Bradford were completely suppressed at this drug dose. Whensterile teneral males were fed on a bloodmeal containing 12 micrograms/ml Samorin and given the infected bloodmeal 10 days later, infections by mature T.vivax, T.congolense and T.b.brucei were completely suppressed. Hence in the management of a tsetse eradication programme utilizing the SIR method, it is recommended that the sterile teneral male tsetse should, prior to release, be given a bloodmeal containing Samorin at 12-15 micrograms/ml blood. This will effectively suppress future disease transmission.     

A comparison of African buffalo, N''Dama and Boran cattle as reservoirs of Trypanosoma congolense for different Glossina species

Teneral Glossina morsitans centralis Machado were fed on the flanks of the African buffalo (Syncerus caffer Sparrman), N'Dama (Bos taurus L.) or Boran (Bos indicus L.) cattle infected with Trypanosoma congolense Broden. The infected tsetse were maintained on rabbits and on day 30 after the infected feed, the surviving tsetse were dissected to determine the infection rates. The mean infection rates (% +/- SE) in the midgut of tsetse fed on buffalo, N'Damas and Borans were 23.5 +/- 3.3, 31.6 +/- 2.7 and 33.7 +/- 4.6, respectively. The differences were not significant. However, the mean mature infection rate in tsetse fed on the buffalo (13.2 +/- 2.1%) was significantly lower compared to the rates in tsetse fed on the N'Dama (20.4 +/- 1.4) or the Boran cattle (21.4 +/- 1.1). When groups of teneral G.m.centralis, G.pallidipes Austen, G.p.gambiensis Vanderplank, G.f.fuscipes Newstead, G.brevipalpis Newstead and G.longipennis Corti were fed simultaneously on either an infected buffalo, an N'Dama or a Boran steer, the mature infection rates ranged from 0 to 16.1%. Irrespective of the host species used, the T.congolense infection rate was highest in G.m.centralis, lowest in the palpalis and fusca group tsetse, with G.pallidipes being intermediate. Nevertheless, the trypanoresistant African buffalo and N'Dama may serve as reservoirs of T.congolense as can trypanosusceptible Boran cattle.     

Positive correlation between the body weight of anestrous goats and their response to the male effect with sexually active bucks

In the present study, we analyzed the results of two years of response to the male effect in seasonally anestrous goats to investigate whether the activation of female reproductive activity by the male effect is related to the body weight of the females. Seventy-nine adult female Mexican mixed breed goats were used. The anestrous females were exposed during 15 days to sexually active males, and were classified into three categories according to their mean body weight +/-SD (42 +/- 9 kg) (Light: < or = 33 kg, n = 19; Medium: 34-50 kg, n = 46; Heavy: > or = 51 kg, n = 14). More than 98% of the goats from the Medium and Heavy groups showed at least one estrus behavior within the first 15 days following the introduction of the bucks, versus only 63% of the females from the Light group (P < 0.01). The interval between the introduction of the males and the onset of estrus behavior was longer in the females of the Light and Medium groups (4.2 +/- 0.8 and 3.3 +/- 0.3 days) than in the females of the Heavy group (2.0 +/- 0.2 days; P < 0.03). Also, body weight was negatively correlated with latency to first estrus (Spearman r = -0.57; P < 0.001). These results are in agreement with the hypothesis that the ability of anestrous goats to respond to the male effect is positively influenced by their body weight.     

Heat curing Metaseiulus occidentalis (Nesbitt) (Acari,Phytoseiidae) of a fitness-reducing microsporidium

Laboratory colonies of the predatory mite Metaseiulus occidentalis in Gainesville, FL were found to be infected with an undescribed microsporidium. Experiments were performed to quantify the effect of infection on the fitness of M. occidentalis and to determine if heat treatment can cure mites of the microsporidium. The colonies tested were derived from an isofemale line so that differences in performance could be attributed to the presence of microsporidia. A subcolony of an uninfected isofemale line was infected with the microsporidium by feeding females infected eggs from another colony of M. occidentalis. Infected mites had a shorter mean (+/-SD) female life span (7.4 +/- 2.9 vs. 10.0 +/- 2.8 days), lower mean oviposition (1.6 +/- 0.7 vs. 2.2 +/- 0.4 eggs/day), and a male-biased sex ratio (43 +/- 16% vs. 57 +/- 15% female progeny). The infection was reduced temporarily in colonies initiated from mites that were reared in a growth chamber at 33 degrees C from egg to adult, but healthy colonies only were established from the progeny of the heat-treated adults. These colonies remained free of infection for 10 weeks.     

Trypanosoma vivax: mechanical transmission in cattle by one of the most common African tabanids,Atylotus agrestis

The role of mechanical vectors in the transmission of African livestock trypanosomes has always been controversial relative to tsetse flies, their cyclical vectors. An experiment was carried out in Burkina Faso to demonstrate mechanical transmission of Trypanosoma vivax by one of the most common tabanids in Africa: Atylotus agrestis. Eight heifers (crossbred zebuxBaoulé), free of trypanosome infection, were kept in a corral covered by a mosquito net, together with two heifers infected experimentally with a local stock of T. vivax. On average, 324 A. agrestis, freshly captured with Nzi traps, were introduced daily over 20 days. Parasitological, PCR and serological examinations were carried out regularly to assess infections and levels of parasitaemia. Microscopic examination of buffy-coats indicated that five of the eight receiver-heifers were infected on days 8, 13, 32, 41, and 48. PCR results indicated that these five heifers were already infected by day 13. Mechanical transmission of T. vivax by A. agrestis was demonstrated unequivocally, at a high rate (63% in 13-20 days). Conditions of transmission in this experiment are discussed in terms of natural rates of challenge. The importance of tabanids as mechanical vectors of T. vivax should be re-considered, in light of these results. Creation of tsetse free zones in Africa will generally lead to the disappearance of T. congolense, T. brucei, and most often T. vivax as well; however, in areas where T. vivax can be mechanically transmitted, clearance of tsetse may not be sufficient to eradicate livestock trypanosomosis.     

Sex separation of tsetse fly pupae using near-infrared spectroscopy

Implementation of the sterile insect technique for tsetse (Glossina spp.) requires that only sterile male insects be released; thus, at some stage of the fly production process the females have to be removed. A further constraint in the use of the sterile insect technique for tsetse is that the females are needed for colony production and hence, a non-destructive method of sex separation is required. In most tsetse sterile insect technique programmes thus far, females have been eliminated from the released material by hand-separation of chilled adults. Using near-infrared (NIR) spectroscopy, significant differences have been found between the spectra for the pupae of male and female G. pallidipes Austen. Significantly, the differences appear to be maximized 4-5 days before emergence of the adults. Tsetse fly pupae up to five days before emergence can be sexed with accuracies that generally range from 80 to 100%. This system, when refined, will enable effective separation of male and female pupae to be carried out, with emerged females being returned to the colony and males being irradiated and released. If separation can be achieved five days before emergence, this will also enable irradiated male pupae to be shipped to other destinations as required. Other Diptera were evaluated using this system but had lower classification accuracies of 50-74%. This may be due to the difference in reproductive physiology between these different fly groups.     

Studies on the transmission of a West African stock of Trypanosoma vivax to rabbits,rats, mice and goats by Glossina morsitans morsitans and G. m. centralis

The cyclical transmission of a West African stock of Trypanosoma vivax by Glossina morsitans morsitans and G. m. centralis was studied. It was possible to transmit this parasite amongst rabbits, rats, mice and goats. Whereas goats and mice succumbed to the disease very rapidly, rats and rabbits showed scant and transient parasitaemia and frequently suppressed the infection. A trypanosome challenge using single infected tsetse showed that goats became infected much more readily than mice. The infected vector can transmit the infection throughout its life but not at every feed.     

Juvenile hormone titre and egg production in Tenebrio molitor infected by Hymenolepis diminuta: effect of male and/or female infection,male age and mating

Infection of Tenebrio molitor with Hymenolepis diminuta induces curtailment of female fertility. We examined ovulation and oviposition, and associated titres of juvenile hormone (JH), in relation to parasitism and mating. Oviposition was significantly increased in infected mated and virgin beetles by days 6 and 9 post-emergence. Ovulation was not changed by infection; by the end of the 18-day experiment, the total number of laid eggs was not significantly altered. On day 6, JH levels were significantly higher in virgin infected insects, compared to non-infected controls (236+/-37.7 and 107+/-9.62 pg/g wet weight). Oviposition increased after mating, but total eggs ovulated remained the same. JH levels were higher in mated females on days 12 and 18 post-emergence, for infected and control insects. Previous studies suggested that male reproductive potential might rise following infection, because uninfected females lay more eggs when mated to infected males. We tested whether this caused an increase in female JH. Males were mated on days 5 or 12, when significant changes in their reproductive physiology begin to be observed, and are maximal, respectively. However, male age was of greater significance in promoting JH levels in females (p=0.001), than infection status of either partner (p=0.33).     

Survival and reproductive performance of female Glossina morsitans morsitans when maintained on the blood of different species of wild mammals

A study was carried out to determine the effect on the reproductive performance of female Glossina morsitans morsitans Westwood when allowed to feed, in vitro, for 63 days on fresh defibrinated blood of buffalo, bushbuck, cattle, eland, oryx, warthog, waterbuck or wildebeest. There were marginal differences in the survival and reproductive performance between eight different groups of tsetse, 200 per group, when fed on the blood of these mammalian species. When allowed to feed for 14 consecutive days on the blood of buffalo, wildebeest or warthog, the mean number of feeds were 6.2 +/- 0.3, 6.5 +/- 0.3 and 6.3 +/- 0.3, respectively. The mean weight of the bloodmeal taken also did not differ significantly between these three groups. Whereas the protein patterns of the blood plasma of the above eight host animals were different, the protein patterns of the haemolymph from tsetse fed on the blood of these hosts were identical. It is thus concluded that the preference shown by tsetse for some mammalian species investigated here may not be based on any aspect of the nutritional value of their blood.     

Trypanosoma congolense: host responses following tsetse transmitted infection of Kilifi isolates in goats

East African x Galla goats, when infected with Trypanosoma congolense isolates from the Kilifi area of Kenya by Glossina morsitans centralis, did not develop the characteristic chancre reaction at the bite sites, whereas bites of tsetse infected with the cloned T. congolense IL.1180 from Serengeti, Tanzania, resulted in chancres in the same goats. Histological changes could not be observed in skin biopsies collected 8 or 9 days after infection with Kilifi isolates. However, all goats became parasitemic about 10 days after challenge. It is concluded that the absence of chancre development is a characteristic feature of T. congolense parasites from Kilifi. The isoenzyme analysis of clones of two T. congolense Kilifi isolates and the T. congolense clone IL.1180 indicated that they belong to different zymodemes. Neutralizing antibodies to homologous metacyclic variable antigen types were detected in six out of seven (86%) of the sera from goats infected with a clone or stock of a T. congolense Kilifi isolate, 20 days after infection. Goats primed by tsetse transmitted infection with a stock or clone of T. congolense from Kilifi and treated with Berenil were, in three out of eight cases (37%), not immune to homologous challenge. It is suggested that the reduced immune response to metacyclic variable antigen types could be a result of the absence of cellular infiltration, i.e., chancre development in the skin at the tsetse bite site. It is concluded that the use of the chancre reaction as a marker for serodeme analysis of recently isolated stocks of T. congolense from Kilifi was not feasible.     

Survival,fecundity, and body mass of Amplicephalus curtulus influenced by ‘Candidatus Phytoplasma ulmi’ (16SrV‐A) infection

The leafhopper Amplicephalus curtulus Linnavuori & DeLong (Hemiptera: Cicadellidae) can transmit ‘Candidatus Phytoplasma ulmi’ (16SrV‐A) from a native Chilean shrub, Ugni molinae Turcz. (Myrtaceae), to ryegrasses. A recent study showed that this phytoplasma reduced the total protein content and the activity of detoxifying enzymes in A. curtulus, which could also affect its vector fitness. This study evaluated the effect of ‘Ca. Phytoplasma ulmi’ on the longevity, fecundity, and body mass of A. curtulus. Both females and males were exposed to ‘Ca. Phytoplasma ulmi’‐infected plants for 96 h, whereas a control group remained unexposed. Quartiles from adult emergence to 75% (t₇₅), 50% (t₅₀), and 25% (t₂₅) survival rates were determined for each leafhopper survival distribution. The dry weight was also established at the end of the experiment. The adult lifespan of phytoplasma‐infected males and females was significantly lower than that of the uninfected leafhoppers in quartile survival distributions t₅₀ and t₂₅. The phytoplasma‐infected males and females lived 3 and 4 weeks less than uninfected ones in the last quartile, respectively. Fecundity was established by number of nymphs per female (in four periods) in phytoplasma‐infected and uninfected assays. In general, the weekly pattern of the number of nymphs per phytoplasma‐infected female was lower than that of uninfected leafhoppers; it was 37% lower at the end of the experiment. Phytoplasma‐infected females weighed significantly less (11%) than uninfected individuals. Phytoplasma‐infected males weighed 8% less than uninfected ones, but this difference was not significant. Our data indicated that ‘Ca. Phytoplasma ulmi’ negatively affected the fitness of A. curtulus, and nymphs produced by phytoplasma‐infected females varied over time, which may influence the disease dynamics in nature or in field crops.     

A cost-benefit analysis of feeding in female tsetse

Abstract. Three models for feeding in female tsetse are considered. Model I: there is a prolonged non-feeding phase after each meal followed by feeding at a constant rate, with a constant probability of dying as a consequence of feeding. Model II: the feeding rate increases linearly after each meal. Model III: the feeding rate increases exponentially after each meal. In Models II and III the feeding hazard is a linear function of the probability of feeding. Production of viable female offspring is estimated under each model, making allowance for losses of adults due to starvation and to background and feeding mortality, losses of pupae due to predation and parasitization, and losses of young flies if their mothers take insufficient blood during pregnancy. Under Model I, if females require three meals to produce viable pupae in 9 days, then for a non-decreasing population with a background mortality of 1%/day, and 25% pupal losses due to predation and parasitism, the feeding risk must be ≤5%/feed. At this maximum level the non-feeding phase should be 2–2.5 days for optimal productivity, with a mean feeding interval of 60–72 h. If the background mortality is 2%/day, feeding losses cannot exceed 1%/feed for a non-decreasing population. If four or five meals are required for the production of fully viable pupae, the optimal values of the non-feeding phase and mean feeding interval tend towards 1 and 2 days respectively. Under Models II and HI the mean feeding interval is 50–60 h for optimal productivity (with variances 3 times as large as for Model I), in good agreement with estimates from recent models for feeding and digestion. Field evidence suggests that feeding tsetse take greater risks as their fat levels dwindle. This should result in feeding (and feeding mortality) rates which increase during the feeding phase - as assumed in Models II and III but not in Model I. These models allow greater flexibility than Model I, because flies can feed early in the hunger cycle, at low probability, as long as the feeding risk is also low.     

Factors affecting abundance of Triaenophorus infection in Cyclops strenuus, and parasite-induced changes in host fitness

Factors affecting the abundance of Triaenophorus crassus and Triaenophorus nodulosus procercoids in their copepod first intermediate host, Cyclops strenuus, and effects of infection on feeding behaviour, reproduction and survival of the host were studied experimentally. When exposed to the same number of coracidia, copepods harboured considerably less procercoids in the trials where ciliates or Artemia salina nauplii were given as alternative food items. The prevalence of infection was higher in adult copepods as compared with copepodite stage IV and stage V, and higher in stage V than in stage IV. The prevalences in adult females and males did not differ significantly from each other. The frequency of females carrying egg sacs was lower among infected than among exposed uninfected and unexposed copepods. The rate of feeding on Artemia nauplii remained at the same level in uninfected copepods, but decreased strongly in infected copepods during 7 days p.i. The survival of unexposed, exposed uninfected and infected copepods did not differ significantly from each other for the first 11 days post-exposure, but the mortality of infected copepods increased significantly after 3 weeks post-exposure. However, the rate of development and mortality of copepods might have been affected by the apparently arrested development of stage IV copepodites found in the experiment. Some of the contradictions between these results and earlier observations are suggested to be caused by the differences in the duration of exposure, intensity of infection and duration of observation post-exposure in the present study as compared with other experiments.     

Effect of puparia incubation temperature: increased infection rates of Trypanosoma congolense in Glossina morsitans centralis, G.fuscipes fuscipes and G.brevipalpis

Puparia of Glossina morsitans centralis (Machado), G.fuscipes fuscipes (Newstead) and G.brevipalpis (Newstead) were incubated at 25 +/- 1 degrees C, 28 +/- 1:25 +/- 1 degrees C, day:night or 29 +/- 1 degrees C throughout the puparial period, and maintained at 70-80% relative humidity. Puparial mortality was higher at 29 than at 25 degrees C (optimum temperature) in all three species, particularly in G.f.fuscipes and G.brevipalpis. Adults of G.m.centralis from puparia incubated at 29 degrees C, and those of this subspecies, G.f.fuscipes and G.brevipalpis from puparia incubated at 28:25 degrees C, day:night or 25 degrees C throughout, were infected as tenerals (27 h old) by feeding them at the same time on goats infected with Trypanosoma congolense (Broden) IL 1180 after the parasites were detected in the wet blood film. Infection rates on day 25 post-infected feed were higher in G.m.centralis from puparia incubated at 29 degrees C and in adults of the three different tsetse species from puparia incubated at 28:25 degrees C, day:night, than in those from puparia incubated at 25 degrees C. However, in G.f.fuscipes the labral and hypopharyngeal infection rates were not significantly different from those of the tsetse produced by puparia kept at 25 degrees C.     

Sex‐dependent infection causes nonadditive effects on kissing bug fecundity

The influence of parasites on host reproduction has been widely studied in natural and experimental conditions. Most studies, however, have evaluated the parasite impact on female hosts only, neglecting the contribution of males for host reproduction. This omission is unfortunate as sex‐dependent infection may have important implications for host–parasite associations. Here, we evaluate for the first time the independent and nonindependent effects of gender infection on host reproductive success using the kissing bug Mepraia spinolai and the protozoan Trypanosoma cruzi as model system. We set up four crossing treatments including the following: (1) both genders infected, (2) both genders uninfected, (3) males infected—females uninfected, and (4) males uninfected—females infected, using fecundity measures as response variables. Interactive effects of infection between sexes were prevalent. Uninfected females produced more and heavier eggs when crossed with uninfected than infected males. Uninfected males, in turn, sired more eggs and nymphs when crossed with uninfected than infected females. Unexpectedly, infected males sired more nymphs when crossed with infected than uninfected females. These results can be explained by the effect of parasitism on host body size. As infection reduced size in both genders, infection on one sex only creates body size mismatches and mating constraints that are not present in pairs with the same infection status. Our results indicate the fitness impact of parasitism was contingent on the infection status of genders and mediated by body size. As the fecundity impact of parasitism cannot be estimated independently for each gender, inferences based only on female host infection run the risk of providing biased estimates of parasite‐mediated impact on host reproduction.     

Comparative study on the susceptibility of different laboratory strains of Glossina species to Trypanosoma simiae

Abstract. Teneral tsetse of four Glossina species from laboratory-reared colonies were fed on four Large White pigs infected with three different stocks of Trypanosoma simiae isolated in Coast Province, Kenya. Thereafter the tsetse were maintained on goats and dissected on day 28 to determine the trypanosome infection rates. Glossina brevipalpis was as susceptible as G.pallidipes whilst G.palpalis gambiensis was not susceptible to T.simiae CP 11 a stock causing acute infection, which was isolated from a wild G.austeni. Glossina brevipalpis was as susceptible as G.pallidipes to another stock causing acute infection, T.simiae CP 813 isolated from a wild G.pallidipes. Glossina morsitans centralis was also as susceptible as G.brevipalpis and G.pallidipes whilst G.p.gambiensis was not susceptible to this T.simiae stock. Glossina m.centralis showed very low susceptibility to a stock causing chronic infection, T.simiae CP 1896 isolated from a bushpig, whilst G.brevipalpis, G.p.gambiensis and G.pallidipes could not be infected by this T.simiae stock. Male Glossina were generally more susceptible than females to the three T.simiae stocks.     

Parasitized female mice display reduced aversive responses to the odours of infected males.

The present study showed that parasites influence both the responses of uninfected females to males and the responses of female hosts to infected males. In female laboratory mice one of the consequences of exposure to the olfactory cues associated with an infected male was a reduction of the reactivity to a thermal surface, i.e. pain inhibition or analgaesia. Uninfected oestrous and non-oestrous female mice displayed marked analgaesic responses after exposure to the odours of males infected with either the enteric single-host nematode parasite, Heligmosomoides polygyrus, or the protozoan parasite, Eimeria vermiformis. The uninfected oestrous females distinguished between infected and physically stressed males, displaying a greater analgaesic response to the odours of infected males. These analgaesic responses and their anxiety/ fearfulness-associated behavioural correlates could elicit either a reduced interest in, or avoidance of, parasitized males by females. Oestrous female mice infected with H. polygyrus displayed a reduced analgaesic response to the odours of the infected males and differentially responded to the odours of males infected with either the same (H. polygyrus) or a different parasite (E. vermiformis). An exposure time of 1 min elicited minimal responses to the odours of males infected with the same parasite, H. polygyrus, and an attenuated, though significant, non-opioid peptide-mediated analgaesic response to males infected with E. vermiformis. An exposure time of 30 min elicited similar markedly reduced endogenous opioid peptide-mediated analgaesic responses to the odours of both of the categories of infected males. The responses to the odours of a stressed male were, however, unaffected by the parasitic infection. The reduced analgaesic responses of the parasitized females to the odours of infected males may involve either enhanced odour familiarity and responses to group odour templates and/or neuromodulatory shifts resulting in reduced fearfulness and potentially greater interest in the infected males.     

Longevity and pheromone output in stored-product Bostrichidae

Information on longevity and on the effect of ageing on pheromone signalling in Bostrichidae infesting stored products is important because pheromones play a crucial role in mediating aggregation by the species in storages. The longevity of starved and unstarved Prostephanus truncatus (Horn) and Rhyzopertha dominica (Fabricius) were determined at 28+/-1 degrees C, 65+/-2% RH and L12:D12 cycle. Additionally, the effects of ageing on rate of pheromone emission were investigated in R. dominica by comparing emission rates of the aggregation pheromones Dominicalure-1 (DL1) and Dominicalure-2 (DL2) released by adult males ranging from 4, 8, 12, 24 and 48 weeks of age. Mean survival time of starved male and female P. truncatus was 8.6+/-0.6 and 9.1+/-0.4 days, respectively. Starved R. dominica males lived for 5.7+/-0.2 days, and females for 4.7+/-0.1 days. However, mean survival times were not significantly different for starved males vs. females of either species. Mean survival time of unstarved male and female P. truncatus was 27.5+/-2.0 and 18.0+/-3.3 weeks, respectively, and for unstarved male and female R. dominica was 26.1+/-2.8 and 16.7+/-2.9 weeks, respectively. Difference in mean survival times of unstarved males vs. females in both P. truncatus and R. dominica were significant. Between species, no significant difference was observed in mean survival time between unstarved males of P. truncatus or R. dominica, nor between females of both species. Rate of pheromone emission in R. dominica was higher when the insects were relatively young (4, 8 and 12 weeks old), but declined by almost 55% in treatments where the insect were at about 24 or 48 weeks old, suggesting that recruitment potential of R. dominica might reduce substantially as the insects age.     

Brugia pahangi: effects of maternal filariasis on the responses of their progeny to homologous challenge infection.

Granulomatous lesion formation and immune responses to Brugia pahangi infections were compared in age-matched male progeny of homologously infected and uninfected female jirds. Infections initiated in 2-week-old offspring yielded mean +/- SD adult worm recoveries of 6.0 +/- 5.7 and 4.2 +/- 5.4 in offspring from infected or uninfected mothers, respectively. Infections initiated in 4-week-old offspring resulted in an mean +/- SD recovery of adult worms of 11.3 +/- 11.3 and 10.2 +/- 5.8 in offspring from infected and uninfected mothers, respectively. The ratio of intralymphatic thrombi per intralymphatic worm was similar between infected offspring from infected or uninfected mothers within experiments. Areas of granulomas around B. pahangi antigen-coated beads embolized in the lungs were not significantly affected by maternal origin in infected or uninfected progeny. Offspring infected at 2 or 4 weeks of age from infected mothers exhibited significantly reduced titers of serum IgG antibodies to Brugia antigens at 5-8 weeks postinfection compared to infected offspring of uninfected mothers. Infected offspring from infected mothers also had significantly fewer splenic IgG plaque-forming cells to B. pahangi antigens at 5 weeks postinfection than similarly infected offspring from uninfected mothers. Western immunoblot analysis indicated qualitative and quantitative reductions in serum antibody reactivity to adult B. pahangi antigens in infected progeny of infected females compared to age-matched infected controls. Reduced homologous serum antibody responses in progeny exposed to maternal B. pahangi infection suggest that maternal immunoregulation to filarial antigens may occur. Reduced antibody responsiveness to B. pahangi antigens observed in infected offspring from infected mothers, however, had no demonstrable effect on adult worm burdens, microfilaremias, lymphatic lesion formation, or antigen-specific granulomatous inflammatory responses compared to infected progeny of uninfected mothers.