Egg Batch Size Research Articles

Trait- and density-mediated effects of predation on fecundity and fertility of Aedes aegypti (Diptera: Culicidae) mosquitoes.

Prey populations that encounter predators experience density-mediated effects through lethality and associated numerical changes in the population. Prey also exhibit trait-mediated effects through nonlethal alterations in phenotypic traits associated with exposure to predators. Immature stages of mosquitoes commonly co-occur in habitats along with predators, a natural source of mortality and potential biocontrol agent. Toxorhynchites rutilus Coquillett 1896 is a natural source of mortality with potential as a biological control agent. Previous studies have shown that predation and the mere presence of Tx. rutilus (predator cues) can alter the life-history traits of Aedes aegypti (L. 1762). In addition to observed reductions in recruitment of adults (lethality), exposure to Tx. rutilus without consumption resulted in adult Ae. aegypti females with altered growth and reduced lifespan. To determine the influence of predation on the reproductive biology of Ae. aegypti, we tested the hypothesis that predation, or exposure to predator cues, will compromise the reproduction of adult survivors through reductions in fecundity (egg batch size) and fertility (hatch rate). We observed that for both female and male Ae. aegypti, survival to adulthood was the lowest and development time the shortest in treatments containing prey removal effects, attributable to predation and treatment manipulations of density reduction. There were effects of Ae. aegypti weight, but not predation treatments, on fecundity and fertility. Results suggest that predator-mediated effects on Ae. aegypti derive from lethal effects due to consumption and alterations in other phenotypic traits of survivors, including development, weight, lifespan of adults, and population growth, but not reproductive parameters measured here.

Age‐dependent changes in reproductive allocation in a facultative ectoparasite, the blowfly Lucilia sericata (Meigen) (Calliphoridae)

AbstractOrganisms trade‐off limited resources between life‐history traits to maximize fitness. In particular, costs associated with reproduction are balanced against somatic maintenance and this can result in age‐dependent changes in the optimal allocation of resource to reproduction. Changes in the allocation of resources to reproduction with age were considered in the facultatively parasitic blowfly Lucilia sericata (Diptera: Calliphoridae), using biochemical analysis of lipids in the body and ovary, and lipid and protein in individual eggs. Resource allocation to reproduction, measured as lipid content in the ovary, declined over time. This decline was associated with the production of fewer and smaller eggs per batch. The lipid content of the residual body did not change. A decrease in lipid and increase in protein contents of individual eggs over time, although statistically significant, were relatively slight, suggesting that age‐related changes in nutritional allocation to individual eggs were more subtle than changes in egg batch number or size. This study highlights the insights to be gained from considering both biochemical measures of nutritional allocation, and observable measures of reproductive effort, when evaluating how females balance allocation across competing life‐history traits. Future work should explore how allocation patterns might vary under conditions of resource constraint and whether age‐dependent allocation in laboratory flies is representative of that found in wild populations.

Diet and Oviposition Deprivation Effects on Survivorship, Gonotrophic Dissociation, and Mortality of Anopheles gambiae s.s.

Diet quality is of paramount importance for egg batch size, longevity, and mortality of vector mosquitoes. Oviposition site presence and absence assumed to be dry season means a lot to the survivorship and mortality of most anthropophilic malaria vectors in sub-Saharan Africa. This study has assessed the effect of different diets and oviposition-site deprivation (OSD) on survivorship, longevity, and mortality of An. gambiae s.s. To determine the effect of diet and OSD on mortality, gonotrophic dissociation rates, longevity, and survivorship, six treatments were employed: Blood Fed with Oviposition (BFO), Blood Fed without oviposition (BF), Blood and Sugar Fed with Oviposition (BSFO), Blood and Sugar Fed without oviposition (BSF), Sugar Fed with Oviposition (SFO), and Sugar Fed without oviposition (SF). Mortality and gonotrophic dissociation were monitored daily. This study found that female mosquitoes offered blood meals with sugar solution and oviposition deprivation survived longer than those deprived of oviposition deprivation. Similarly, female mosquitoes fed on blood and provided with oviposition deprivation lived longer than those without oviposition deprivation. The gonotrophic dissociation rates were found to be lower in groups provided with oviposition deprivation. Our results show that OSD has a direct impact on the survivorship, gonotrophic dissociation rate, and longevity of the malaria anthropophilic vector, An. gambiae s.s., regardless of the diet.

The Impact of Insecticide Pre-Exposure on Longevity, Feeding Succession, and Egg Batch Size of Wild Anopheles gambiae s.l.

Background Insecticide resistance among the vector population is the main threat to existing control tools available. The current vector control management options rely on applications of recommended public health insecticides, mainly pyrethroids through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Regular monitoring of insecticide resistance does not provide information on important factors that affect parasite transmission. Such factors include vector longevity, vector competence, feeding success, and fecundity. This study investigated the impacts of insecticide resistance on longevity, feeding behaviour, and egg batch size of Anopheles gambiae s.l. Method The larval sampling was conducted in rice fields using a standard dipper (350 ml) and reared to adults in field insectary. A WHO susceptibility test was conducted using standard treated permethrin (0.75%) and deltamethrin (0.05%) papers. The susceptible Kisumu strain was used for reference. Feeding succession and egg batch size were monitored for all survivors and control. Results The results revealed that mortality rates declined by 52.5 and 59.5% for permethrin and deltamethrin, respectively. The mortality rate for the Kisumu susceptible strain was 100%. The survival rates of wild An. gambiae s.l. was between 24 and 27 days. However, the Kisumu susceptible strain blood meal feeding was significantly higher than resistant colony (t = 2.789, df = 21, P=0.011). Additionally, the susceptible An. gambiae s.s. laid more eggs than the resistant An.gambiae s.l. colony (Χ2 = 1366, df = 1, P ≤ 0.05). Conclusion It can, therefore, be concluded that the wild An. gambiae s.l. had increased longevity, blood feeding, and small egg batch size compared to Kisumu susceptible colonies.

Sexual differentiation, gonad maturation, and reproduction of the Southern Ocean euphausiid Thysanoessa macrura (Sars, 1883) (Crustacea: Euphausiacea)

Thysanoessa macrura (Sars, 1883) is a small, albeit highly abundant, Southern Ocean euphausiid. It has been reported that T. macrura reproduces during late winter, with the reproductive cycle decoupled from periods of high primary productivity in the highly seasonal Southern Ocean. Despite this uncommon reproductive strategy, there has been little work to describe this cycle and quantify the reproductive potential of this species. Thysanoessa macrura collected from Antarctic waters during early September to early October 2007 were used to establish sexual developmental stages, for females and males, to provide a standard means for assessing the reproductive maturity of this species. Seven sexual developmental stages were established for females based upon the organisation of ovaries and their constituent oogonia and oocytes. Four sexual developmental stages were identified in males using secondary sexual characters. A large lipid deposit was identified in the carapace of both sexes, reducing in size with progressive gonadal development, likely fuelling egg and sperm production. Egg-batch size was determined by direct ovarian counts and scaled allometrically with total wet weight. Predicted egg-batch size ranged from 34 to 746 eggs batch –1 for the range of individual sizes studied (30.5–165.6 mg). Using the ratios of the different oocytes remaining after the first-spawning event of females, it was predicted that up to three egg batches can be produced by T. macrura in a single reproductive season. Consequently, the fecundity of T. macrura is estimated at 60 to > 2200 eggs female -1 year -1 . A model of T. macrura reproductive cycle confirms a winter reproductive period and further highlights the reproductive potential of this small-size Southern Ocean euphausiid, providing the first estimates of fecundity reported for this species.

Genotypic differences in embryonic life history traits ofFolsomia quadrioculata(Collembola: Isotomidae) across a wide geographical range

1. Life history traits play a central role in adaptation to specific environmental conditions. Egg development time, hatchling, and egg batch size in 10 populations of the soil‐dwelling collembolan speciesFolsomia quadrioculata(Tullberg, 1871) from diverse habitats across arctic and temperate regions, ranging in latitude from 43 to 81°N were studied.2. For all traits, 15 °C was used as the reference temperature. Phenotypic plasticity was studied by changing temperature to 10 and 20 °C in hatchling size, and to 20 °C in egg development time. The effect of latitude, climatic zone, and summer temperature at their sites of sampling was tested to address the hypotheses that populations from cooler areas would have (i) a faster temperature‐dependent egg development, (ii) a larger hatchling size, (iii) smaller egg batches and (iv) higher phenotypic plasticity3. The first and fourth hypothesis were not supported, whereas the second and third were partly supported when including the whole latitudinal gradient, but not within regions. Plasticity showed a complex pattern, including large differences between populations from similar macroclimates and considerable similarity between some populations from contrasting climates. Small effects of latitude and macroclimatic variables emphasised that local climate and microhabitat should be taken into account when evaluating thermal conditions as possible drivers of population‐specific differences in soil‐dwelling ectotherms.4. There was a trade‐off between egg batch and hatchling sizes. A weak correlation between the population mean egg development time and the mean hatchling size suggested that the populations are, or have been, exposed to differential selection.

Populations of a shrub-feeding butterfly thrive after introduction of restorative shrub cutting on formerly abandoned calcareous grassland

Calcareous grasslands are one of the most species-rich semi-natural habitat types. However, area and species richness have considerably decreased, particularly due to the cessation of grazing or mowing. Accordingly, habitat restoration has become an important issue in the conservation of these grasslands. The aim of this study was to analyse the role of shrub cutting as a measure to restore habitats of the target butterfly Satyrium spini (Denis and Schiffermuller 1775) on formerly abandoned calcareous grasslands. We compared host plant density and occupancy, as well as egg batch density and size between cut, regularly managed and fallow patches. In total, we counted 3372 Rhamnus cathartica host plants on 17 calcareous grassland patches. On 309 (9 %) of these plants, we found a total of 490 batches containing 1168 eggs. Both R. cathartica and S. spini responded rapidly to restoration: Shrub cutting promoted the rejuvenation of the host plant, resulting in a strong population increase of the butterfly species four years after shrub cutting. The density of the preferred small host plants (growth height < 130 cm), their occupancy, as well as the density and size of the batches on these plants, clearly exceeded those of small plants on fallow and even on traditionally managed calcareous grasslands. Based on this study, we recommend shrub cutting on calcareous grasslands as both a restorative and regular management measure for S. spini habitats. Due to the increasing demand for fuel wood, shrub cutting in overgrown grasslands might even no longer be constrained by economic reasons.

The impact of oviposition-site deprivation in gravid females of Anopheles gambiae (Diptera: Culicidae) on fecundity, trophic behaviour and life expectancy

Short and long dry spells occur throughout the year and limit the access of gravid mosquitoes to oviposition sites. Using simulations in laboratory conditions, we explored the possible consequences of a long duration of egg retention on reproductive capacity, trophic behaviour, life expectancy and gonotrophic cycle in a context of breeding-site absence. KISUMU and wild gravid females of Anopheles gambiae were subjected to a delay in egg-laying following the preset modalities as immediate egg-laying versus retention for 5, 10 and 15 days. The egg batch size and the hatching rate were measured. In addition, blood-feeding patterns and life expectancy were investigated. Our study showed that oviposition occurs much faster in the standard susceptible laboratory strain An. gambiae KISUMU with a lapse of 2.2 days than in the wild females of An. gambiae with an average of 5 days between the second blood meal and egg-laying. In this experiment, the egg-retention time did not significantly affect the number of eggs laid. In the absence of breeding sites, the rate of egg-hatching decreased in proportion as the retention time became longer. The study also showed that gravid females deprived of oviposition sites continue to take blood meals. The average longevity of non-gravid females was estimated to be lower than that of gravid females. The oviposition-site deprivation has no impact on female fecundity and blood feeding, but influences egg-hatching.

The effects of oviposition-site deprivation on Anopheles gambiae reproduction

BackgroundThe African malaria mosquito, Anopheles gambiae, depends on availability of suitable surface water for oviposition. Short and long dry spells occur throughout the year in many parts of its range that limit its access to oviposition sites. Although not well understood, oviposition-site deprivation has been found to rapidly reduce egg batch size and hatch rate of several mosquito species. We conducted laboratory experiments to assess these effects of oviposition-site deprivation on An. gambiae and to evaluate the role of nutrition and sperm viability as mediators of these effects.MethodsAnopheles gambiae adults (1–2 d old) from the G3 laboratory colony were assigned to the following treatment groups: oviposition-deprived (fed once and then deprived of oviposition site for 7 or 14 d), multiple-fed control (fed regularly once a week and allowed to lay eggs without delay), and age matched blood-deprived control (fed once, three days before water for oviposition was provided). Egg batch size and hatch rate were measured. In the second experiment two additional treatment groups were included: oviposition-deprived females that received either a second (supplemental) blood meal or virgin males (supplemental mating) 4 days prior to receiving water for oviposition.ResultsAn. gambiae was highly sensitive to oviposition-site deprivation. Egg batch size dropped sharply to 0–3.5 egg/female within 14 days, due to reduced oviposition rate rather than a reduced number of eggs/batch. Egg hatch rate also fell dramatically to 0-2% within 7 days. The frequency of brown eggs that fail to tan was elevated. A supplemental blood meal, but not ‘supplemental insemination,’ recovered the oviposition rate of females subjected to oviposition-site deprivation. Similarly, a supplemental blood meal, but not ‘supplemental insemination,’ partly recovered hatch rate, but this increase was marginally significant (P < 0.069).ConclusionsEven a short dry spell resulting in oviposition-site deprivation for several days may result in a dramatic decline of An. gambiae populations via reduced fecundity and fertility. However, females taking supplemental blood meals regain at least some reproductive success. If mosquitoes subjected to oviposition-site deprivation increase the frequency of blood feeding, malaria transmission may even increase during a short dry spell. The relevance of oviposition-site deprivation as a cue to alter the physiology of An. gambiae during the long dry season is not evident from these results because no reduction in hatch rate was evident in wild M-form An. gambiae collected in the dry season in the Sahel by previous studies.

Dry season reproductive depression of Anopheles gambiae in the Sahel

The African malaria mosquito, Anopheles gambiae, is widespread south of the Sahara including in dry savannahs and semi-arid environments where no surface water exists for several months a year. Adults of the M form of An. gambiae persist through the long dry season, when no surface waters are available, by increasing their maximal survival from 4weeks to 7months. Dry season diapause (aestivation) presumably underlies this extended survival. Diapause in adult insects is intrinsically linked to depressed reproduction. To determine if reproduction of the Sahelian M form is depressed during the dry season, we assessed seasonal changes in oviposition, egg batch size, and egg development, as well as insemination rate and blood feeding in wild caught mosquitoes. Results from xeric Sahelian and riparian populations were compared. Oviposition response in the Sahelian M form dropped from 70% during the wet season to 20% during the dry season while the mean egg batch size among those that laid eggs fell from 173 to 101. Correspondingly, the fraction of females that exhibited gonotrophic dissociation increased over the dry season from 5% to 45%, while a similar fraction of the population retained developed eggs despite having access to water. This depression in reproduction the Sahelian M form was not caused by a reduced insemination rate. Seasonal variation in these reproductive parameters of the riparian M form population was less extreme and the duration of reproductive depression was shorter. Blood feeding responses did not change with the season in either population. Depressed reproduction during the dry season in the Sahelian M form of An. gambiae provides additional evidence for aestivation and illuminates the physiological processes involved. The differences between the Sahelian and riparian population suggest an adaptive cline in aestivation phenotypes between populations only 130km apart.

Effects of Beauveria bassiana on Survival, Blood-Feeding Success, and Fecundity of Aedes aegypti in Laboratory and Semi-Field Conditions

The fungus Beauveria bassiana reduces Aedes aegypti longevity in laboratory conditions, but effects on survival, blood-feeding behavior, and fecundity in realistic environmental conditions have not been tested. Adult, female Ae. aegypti infected with B. bassiana (FI-277) were monitored for blood-feeding success and fecundity in the laboratory. Fungal infection reduced mosquito-human contact by 30%. Fecundity was reduced by (mean ± SD) 29.3 ± 8.6 eggs per female per lifetime in the laboratory; egg batch size and viability were unaffected. Mosquito survival, blood-feeding behavior, and fecundity were also tested in 5 meter × 7 meter × 4 meter semi-field cages in northern Queensland, Australia. Fungal infection reduced mosquito survival in semi-field conditions by 59-95% in large cages compared with 61-69% in small cages. One semi-field cage trial demonstrated 80% reduction in blood-feeding; a second trial showed no significant effect. Infection did not affect fecundity in large cages. Beauveria bassiana can kill and may reduce biting of Ae. aegypti in semi-field conditions and in the laboratory. These results further support the use of B. bassiana as a potential biocontrol agent against Ae. aegypti.

Reproductive success in Anopheles arabiensis and the M and S molecular forms of Anopheles gambiae: Do natural sporozoite infection and body size matter?

Malaria parasites stages prior to sporozoite formation are known to affect the fecundity of several species of mosquitoes in the laboratory, but little is known about this phenomenon in natural conditions especially with sporozoite-infected anophelines. The reproductive success of wild-caught Anopheles arabiensis and the M and S molecular forms of Anopheles gambiae was investigated by comparing females infected with Plasmodium falciparum sporozoites to females free of sporozoites. Association between sporozoite-infected females’ body size and their egg batch size was also measured. There was no significant reduction in egg production due to sporozoite infection among wild females An. arabiensis and the M and S form of An. gambiae. The infected groups and the controls laid similar numbers of eggs. A positive association was found between body size of females infected with P. falciparum and mean egg production. Infected females of the molecular forms of An. gambiae and their sibling species An. arabiensis invest similarly in egg batch size regardless of their body size although the expected egg batch size may differ among them because of differences in their mean body size. A reduction of egg production related to infection status was not observed among females harboring sporozoites. Therefore for the gonotrophic cycles that occur once sporozoites are present, natural infection of all three vectors we studied has no or minimal effect on their densities or their reproductive outputs.

Butterfly Larval Host Plant use in a Tropical Urban Context: Life History Associations, Herbivory, and Landscape Factors

This study examines butterfly larval host plants, herbivory and related life history attributes within Nagpur City, India. The larval host plants of 120 butterfly species are identified and their host specificity, life form, biotope, abundance and perennation recorded; of the 126 larval host plants, most are trees (49), with fewer herbs (43), shrubs (22), climbers (7) and stem parasites (2). They include 89 wild, 23 cultivated, 11 wild/cultivated and 3 exotic plant species; 78 are perennials, 43 annuals and 5 biannuals. Plants belonging to Poaceae and Fabaceae are most widely used by butterfly larvae. In addition to distinctions in host plant family affiliation, a number of significant differences between butterfly families have been identified in host use patterns: for life forms, biotopes, landforms, perennation, host specificity, egg batch size and ant associations. These differences arising from the development of a butterfly resource database have important implications for conserving butterfly species within the city area. Differences in overall butterfly population sizes within the city relate mainly to the number of host plants used, but other influences, including egg batch size and host specificity are identified. Much of the variation in population size is unaccounted for and points to the need to investigate larval host plant life history and strategies as population size is not simply dependent on host plant abundance.

Microscopic and molecular characterization of ovarian follicle atresia in Rhodnius prolixus Stahl under immune challenge

In this work we characterized the degenerative process of ovarian follicles of the bug Rhodnius prolixus challenged with the non-entomopathogenic fungus Aspergillus niger. An injection of A. niger conidia directly into the hemocoel of adult R. prolixus females at the onset of vitellogenesis caused no effect on host lifespan but elicited a net reduction in egg batch size. Direct inspection of ovaries from the mycosed insects revealed that fungal challenge led to atresia of the vitellogenic follicles. Light microscopy and DAPI staining showed follicle shrinkage, ooplasm alteration and disorganization of the monolayer of follicle cells in the atretic follicles. Transmission electron microscopy of thin sections of follicle epithelium also showed nuclei with condensed chromatin, electron dense mitochondria and large autophagic vacuoles. Occurrence of apoptosis of follicle cells in these follicles was visualized by TUNEL labeling. Resorption of the yolk involved an increase in protease activities (aspartyl and cysteinyl proteases) which were associated with precocious acidification of yolk granules and degradation of yolk protein content. The role of follicle atresia in nonspecific host–pathogen associations and the origin of protease activity that led to yolk resorption are discussed.

Behaviour of Sitodiplosis mosellana (Diptera: Cecidomyiidae) on spring wheat spikes with and without oviposition deterrence

AbstractWheat, Triticum L. (Poaceae), varieties with deterrence to oviposition by the wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), can be useful in reducing seed damage. The behaviour of ovipositing females on spring wheat, T. aestivum L., with and without oviposition deterrence was investigated to account for observed differences in oviposition on deterrent and nondeterrent hosts. On deterrent wheat, 34% of females landing oviposited compared with 100% of females landing on nondeterrent wheat. The sequence of female behaviours just prior to egg-laying on deterrent spikes was similar to that on nondeterrent spikes. The length of time required to lay an egg and mean egg-batch size were similar on deterrent and nondeterrent wheat, but females spent nearly twice as long on the latter. After landing on deterrent wheat, females took longer to begin ovipositing and longer to leave after the last oviposition event than did females on nondeterrent wheat, which further reduced the time available for oviposition on deterrent compared with nondeterrent wheat. As a result of these behavioural differences, deterrence reduced oviposition by more than 60%.

Effects of Thermal Conditions on the Sex Ratio of Pseudaulacaspis pentagona Targioni (Hemiptera: Diaspididae), at the Early Stage of Ovogenesis and Egg Batch Size

Effects of Thermal Conditions on the Sex Ratio of Pseudaulacaspis pentagona Targioni (Hemiptera: Diaspididae), at the Early Stage of Ovogenesis and Egg Batch Size

Evaluating the Effect of Postmating Isolation Between Molecular Forms of &lt;I&gt;Anopheles gambiae&lt;/I&gt; (Diptera: Culicidae)

Multiple families representing all possible combinations of crosses between the two molecular forms of Anopheles gambiae sensu stricto Giles and their hybrids were set up using forced mating between offspring of wild-collected females. The results showed that the reproductive output of hybrids and their backcrosses was similar to that of the pure forms as measured by egg batch size, hatching rate, and larval development success. No sex ratio distortion was found among the offspring. We concluded that postmating developmental barriers do not contribute to the isolation between the molecular forms.

Evaluating the Effect of Postmating Isolation Between Molecular Forms of Anopheles gambiae (Diptera: Culicidae)

Multiple families representing all possible combinations of crosses between the two molecular forms of Anopheles gambiae sensu stricto Giles and their hybrids were set up using forced mating between offspring of wild-collected females. The results showed that the reproductive output of hybrids and their backcrosses was similar to that of the pure forms as measured by egg batch size, hatching rate, and larval development success. No sex ratio distortion was found among the offspring. We concluded that postmating developmental barriers do not contribute to the isolation between the molecular forms.

Reproductive Output of Female &lt;I&gt;Anopheles gambiae&lt;/I&gt; (Diptera: Culicidae): Comparison of Molecular Forms

Knowledge of ecological differences between the molecular forms of Anopheles gambiae Giles (Diptera: Culicidae) might lead to understanding of their unique contribution to disease transmission, to better vector control, and to identification of the forces that have separated them. We compared female fecundity measured as egg batch size in relation to body size between the molecular forms in Mali and contrasted them with their sibling species, Anopheles arabiensis Patton. To determine whether eggs of different egg batches are of similar "quality," we compared the total protein content of first-stage larvae (L1s), collected < 2 h after hatching in deionized water. Egg batch size significantly varied between An. gambiae and An. arabiensis and between the molecular forms of An. gambiae (mean batch size was 186.3, 182.5, and 162.0 eggs in An. arabiensis and the M and the S molecular form of An. gambiae, respectively). After accommodating female body size, however, the difference in batch size was not significant. In the S molecular form, egg protein content was not correlated with egg batch size (r = -0.08, P > 0.7) nor with female body size (r = -0.18, P > 0.4), suggesting that females with more resources invest in more eggs rather than in higher quality eggs. The mean total protein in eggs of the M form (0.407 microg per L1) was 6% higher than that of the S form (0.384 microg per L1), indicating that the M form invests a greater portion of her resources into current (rather than future) reproduction. A greater investment per offspring coupled with larger egg batch size may reflect an adaptation of the M form to low productivity larval sites as independent evidence suggests.

Reproductive Output of FemaleAnopheles gambiae(Diptera: Culicidae): Comparison of Molecular Forms

Knowledge of ecological differences between the molecular forms of Anopheles gambiae Giles (Diptera: Culicidae) might lead to understanding of their unique contribution to disease transmission, to better vector control, and to identification of the forces that have separated them. We compared female fecundity measured as egg batch size in relation to body size between the molecular forms in Mali and contrasted them with their sibling species, Anopheles arabiensis Patton. To determine whether eggs of different egg batches are of similar "quality," we compared the total protein content of first-stage larvae (L1s), collected <2 h after hatching in deionized water. Egg batch size significantly varied between An. gambiae and An. arabiensis and between the molecular forms of An. gambiae (mean batch size was 186.3, 182.5, and 162.0 eggs in An. arabiensis and the M and the S molecular form of An. gambiae, respectively). After accommodating female body size, however, the difference in batch size was not significant. In the S molecular form, egg protein content was not correlated with egg batch size (r = −0.08, P > 0.7) nor with female body size (r = −0.18, P > 0.4), suggesting that females with more resources invest in more eggs rather than in higher quality eggs. The mean total protein in eggs of the M form (0.407 μg per L1) was 6% higher than that of the S form (0.384 μg per L1), indicating that the M form invests a greater portion of her resources into current (rather than future) reproduction. A greater investment per offspring coupled with larger egg batch size may reflect an adaptation of the M form to low productivity larval sites as independent evidence suggests.