Egg Incubation Period Research Articles

Parental Behavior Controls Asynchronous Hatching, but Not Incubation Period, in the Magellanic Penguin: A Commentary on Rebstock and Boersma (2011)

Abstract. Rebstock and Boersma (2011) recently explored variation in the temperature and incubation period of eggs within clutches of the Magellanic Penguin (Spheniscus magellanicus). They defined incubation period as “the time from the laying of an egg to its hatching” and concluded that parental behavior explained why the incubation period of second eggs was shorter than that of first eggs and controlled asynchronous hatching. While we agree that parents influenced asynchronous hatching by delaying the onset of incubation, we argue that their conclusions are based on an unconventional definition of incubation period. They included the period before the delayed onset of incubation in the incubation period, which leads to confusion. We state that the incubation period cannot include the time before the (delayed) onset of incubation when parents are not warming the eggs. As regards this latter and widely accepted definition, Rebstock and Boersma (2011) provided a large dataset showing that incubation consi...

Aspectos da biologia e morfologia de machos da mosca-dos-brotos (Diptera: Lonchaeidae)

O objetivo deste trabalho foi caracterizar os aspectos biológicos e morfológicos de machos da mosca-dos-brotos Neosilba perezi (Diptera: Lonchaeidae). Em laboratório, o período de incubação dos ovos foi de dois dias, em média, com 55,5% de viabilidade. Criadas em dieta artificial, à base de farinha de mandioca, o tempo médio de desenvolvimento da larva recém-eclodida até a formação de pupa foi de 15 dias, e o período pupal médio foi de 23 dias. O ciclo biológico (ovo-adulto) foi de aproximadamente 40 dias. Os ovos são de coloração branca, forma elíptica e têm 960 ± 5,30 µm de comprimento e 290 ± 1,30 µm de largura na região central; as larvas de aspecto vermiforme, terceiro ínstar, são de coloração branco-leitosa e medem ± 10 mm de comprimento (3º ínstar).

Development and fecundity rate of Tribolium castaneum (Herbst) on Distillers Dried Grains with Solubles

This research focused on the influence of two samples of corn Distillers Dried Grains with Solubles (DDGS) obtained from an “old” generation dry-grind fuel ethanol plant as a food and oviposition resource for red flour beetle, Tribolium castaneum, in contrast with traditional flour (90%)/yeast (10%) diet. Larval development was significantly faster on a flour/yeast diet (18.6 d) compared to the DDGS sample 1 (44.1 d) and DDGS sample 2 (34.5 d). DDGS sample 1 had the highest larval mortality (38.7%) with a wider mortality range (6.7–66.7%) compared with flour/yeast (4.4%, range 0–14.3%) and DDGS sample 2 (7.1, range 0–26.7%). Both DDGS diets and the flour/yeast diet had no significant influence on egg incubation period or pupation time and percentage of egg hatching or pupal mortality. Additionally, fecundity was significantly lower on DDGS compared to the flour/yeast diet (18.0, 36.5, and 175.5 eggs per female on DDGS sample 1, DDGS sample 2, and flour/yeast diet, respectively). These results indicate that this type of DDGS is not a suitable developmental diet compared to the standard laboratory diet and that the addition of this type of DDGS to animal feeds should not increase feed vulnerability to flour beetle infestation. A comparison of DDGS samples by particle size indicated that the larger particle size, sample 1 was less suitable for T. castaneum oviposition and development.

Effect of Different Photo Periods on the Biological Parameters of Chrysoperla carnea under Laboratory Conditions

Many insects are known to give response in adaptive way for seasonal changes in day lengths. Photoperiod control’s many developmental responses and allows insects to survive periods of unfavorable environmental conditions. An experiment was conducted to study the effect of different photoperiod lengths on biological parameters of green lacewing, Chrysoperla carnea. Four different photoperiod regimes were selected with varying lengths of light/dark hours (8/16, 10/14, 24/0 and 0/24) at a constant 26±2°C temperature with 70 % RH (relative humidity) in the laboratory. Photoperiod regimes affected the development of C. carnea from egg to adult. In complete darkness (L: 0 D: 24), minimum egg laying, hatching, larval survival and adult emergence were recorded. Incubation period for eggs, larval period and pupal duration were also significantly longer in complete darkness as compared to other treatments 8L: 16D and 10L: 14D. Whereas, the treatment with complete light hours (L: 24, D: 0) resulted in maximum egg laying hatching, larval survival and adult emergence. The incubation period for eggs, larval and pupal duration significantly shortened as compared to other treatments.Sex ratios skewed towards female when full light hours were provided for development.

Novel Rearing Technique, Developmental Biology, Fecundity and Morphometries of the Brown Cocoa Mirid, Sahlbergella singularis Haglund (Hemiptera: Miridae) in Southwestern Nigeria

The brown cocoa mirid, Sahlbergella singularis Haglund, a major insect pest of cocoa in Nigeria, could cause 80% loss in yield. Fecundity, morphometries and developmental biology of the insect were investigated by a new rearing technique. The first rearing phase involved transfer of 20 day old nymphs collected from field cocoa pod into rearing chamber equipped with regulated conditions of relative humidity (90 ± 5%) and temperatures (22 – 24°C) while the second phase was carried out oil sleeved pods on the cocoa trees under natural conditions. Each of the life stages was isolated, measured and described. Nymphal instars were separated on the basis of the cast off exuviae. The life cycle from egg to adult lasted an average of 41.1 days while the average egg incubation period was 14.1 days (31.3% of the total developmental time). There were five nymphal instars with total mean duration of 27 days. There were significant differences in the body morphometries of each of the life stages (P<0.05) for body length, abdominal width and antennal length. The sex ratio of male to female was 1:1.03. The potential fecundity of S. singularis was 42.20 ± 4.96 eggs per female from dissected gravid females whereas the mean actual fecundity from mated females was 37.90 ± 3.09 eggs per female. This study has made available homogenous populations of S. singularis. The indepth knowledge of biology of the pest acquired here will assist in the future development of efficient and ecologically sound management strategies for its control

Factors influencing the success of salmonid egg development in river substratum

AbstractInterstitial water conditions in the hyporheic zone of the stream bed are determinants of salmonid egg hatching success. We used standardised egg exposures to develop and validate discriminant analysis and generalised linear model models linking the hatching success of brown trout (Salmo trutta) with physicochemical factors of the interstitial zone (e.g., oxygen, specific conductance, nitrate, nitrite, ammonium, pH and redox potential). Interstitial water quality was identified as a limiting factor for egg development (median of relative hatching rates = 0.23). Hatching success was unimodal in hatchery and field references incubated in free‐flowing water, but bimodal (very high or very low hatching success) in natural sediment exposures. The effects of physicochemical factors on the hatching success ofSalmo truttastrongly depended on both the time and spatial scale analysed. The variables retained in the models differed between the macroscale (over all rivers), the river‐specific scale (within a river) and the microscale (at different sediment depths). Egg hatching success decreased with increased substratum depth (decrease of 26% in 150 mm compared with 50 mm). Increasingly more variable interstitial water conditions (e.g., oxygen) throughout the egg incubation period suggest progressive degradation rates in the stream substratum during the incubation period at the microscale level. Consequently, consideration of different spatial and temporal scales is necessary for the evaluation of habitat quality in salmonid conservation and catchment management plans.

Reproduction of <i>Omalonyx matheroni</i> (Gastropoda: Succineidae) under laboratory conditions

The life histories of succineids have received relatively little attention. To evaluate life history characteristics of Omalonyx matheroni, we studied a Brazilian population (Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala, in Caratinga, Minas Gerais, Brazil) under laboratory conditions. The aims of the present study were (1) to describe in detail an appropriate rearing method; (2) to investigate the effects of different temperature and photoperiod conditions; and (3) to assess the effects of self and cross-fertilization on the reproductive biology of these mollusks. We studied the oviposition site, the time to sexual maturity and the influences of photoperiod and temperature on reproductive parameters of O. matheroni reared under laboratory conditions. We tested three combinations of temperature and photoperiod, designated A, B and C (A: 25degreeC, 24 hours of light; B: environmental conditions of temperature and photoperiod, characterized as follows: average maximum temperature=27.1 degreeC, average minimum temperature=18.3 degreeC, average day length=12.06 hours; and C: 25 degreeC, zero hours of light) and two rearing densities (I: isolated and G: grouped) on reproductive parameters (number of eggs per egg mass, number of unviable eggs per mass, egg mass incubation period, and duration of the hatching period). A total of 186 individuals and 565 egg masses were studied. Data were analyzed by Student's t-test, two-way ANOVA and Chi-Square test. Eight generations were produced (March/2004-March/2006), from 35 field specimens, 91% of 3 197 eggs hatched. The time to sexual maturity was approximately three months for individuals reared in groups or in isolation (Student's t-test: t=1.41, df=31, p=0.16); however, they differed significantly in weight (Student's t-test: t=3.6, df=31, p<0.001). Regarding the influences of temperature and photoperiod on reproductive parameters, under natural environmental conditions, individuals produced a greater number of eggs per mass (ANOVA: F2573,=84.15, p<0.001), with a longer incubation period (ANOVA: F2559=170.05, p<0.001). The extreme photoperiod conditions of 24 hours of light or zero hours of light likely imposed stress and could be related to the significant reductions in the number of eggs per mass, and egg incubation period as well as the increased synchrony in egg hatching. No correlations were observed between the number of unviable eggs per mass and the temperature, photoperiod (ANOVA: F2573=0.87, p=0.92) or rearing density (ANOVA: F1 .573=0.21, p=0.64). Individuals reared in isolation under natural conditions produced more eggs per mass and did not presented any disadvantage with respect to the variables analyzed as compared to the animals reared in groups. These results indicate that O. matheroni can successfully reproduce by selfing.

EFFECTS OF PHOTOPERIOD ON THE BIOLOGY OF THE GRANARY WEEVIL, SITOPHILUS GRANARIUS L. IN THE LABORATORY

The present study investigated the effects of photoperiod on the development of immature stages, oviposition periods and adult longevity of the granary weevil, Sitophilus granarius L. at constant temperature of 27±2C° and 70±5°% R.H. in the laboratory. Statistical analysis proved considerable effect of 16 and 24 hr. photophase on the incubation period of eggs. At complete darkness the shortest larval duration (19.6 days) was observed while the longest one (25.3 days) was shown at 24 hr. photophase. Pupal exposed to continuous light showed the lowest mean pupal period (4.7 days) as compared with 5.4 days for the pupal exposed to 16 hr. light. In addition, the period from egg to adult was markedly influenced by the tested photoperiods. The longest developmental period (40.9 days) was observed under continuous light while the shortest one was recorded at complete darkness. The oviposition periods of adult females decreased by increasing the photophase periods. Adult females kept in complete darkness recorded the longest oviposition period (89.4 days). Meanwhile, the shortest period (84.6 days) was reported for females lived under continuous light. Also, adults exposed to complete darkness lived longer than those lived under continuous illumination, however both sexes lived nearly equal periods at any tested photoperiodic regimes

Biology ofChiloloba orientalis

This study, related to emergence of the cetoniid beetle, Chiloloba orientalis D and R (Coleoptera: Scarabaeidae: Cetoniinae), was conducted annually from August to the middle of October from 2007 to 2010 in maize (Zea mays L. (Poales: Poaceae)), sorghum (Sorghum bicolor (L.) Moench), and grass (Hetropogon contortus (L.) P. Beauv. ex Roem. and Schult., Apluda mutica L.) cultivated fields in a selected plot of grassland in Kolhapur, Maharashtra, India. Adults of C. orientalis feed on the inflorescence of S. bicolor, Z. mays, H. contortus and A. mutica. The occurrence of adults in this study indicates that the emergence of beetles coincides with the flowering period of its host plants. The immature stages of this beetle feed on the decaying organic matter of crop residues in composting heaps, indicating these immature stages play a key role in the recycling of organic waste of plant and animal origin and help in the enrichment of soil nutrients, especially in the red brown soil where primary decomposers are scarce. This study provides detailed information on the morphological peculiarities of immature stages with the duration required for the completion of the life cycle. The average incubation period of eggs was 15.2 days. The first, second, and third instar lasted for 22.7, 54.3, and 46.6 days respectively. The mean pupal period was 14.7 days. The average adult longevity was 9.4 days.

Reproductive and Growth Traits of Parents and F1 Hatchlings of Achatina achatina (L) Snails under Mixed Feeding Regime with Graded Levels of Swamp Taro Cocoyam (Cytosperma chamissonis) and Paw paw leaves (Carica papaya)

Achatina achatina snails were raised on mixed feeding regime of forage and diets containing graded levels of sun-dried swamp taro cocoyam (Cytosperma chamissonis) meal to assess the parent snails’ reproductive traits and the growth performance of their juveniles. Ninety parent snails, forty-five (45) each of the black-skinned (BS) and white-skinned (WS) ectotypes weighing 50.75 to 62.50 g and 48.40 to 60.75 g respectively constituted the mating groups [black-skinned x black-skinned (BS X BS), white-skinned x white-skinned (WS X WS) and black-skinned x white-skinned (BS X WS)] studied. Snails in each mating group were randomly allocated to five diets containing different levels of the test ingredient. Results of the reproductive traits of the study showed that inclusion of cocoyam above 50% had negative effects. The results revealed that snails on the control diet (without cocoyam meal) consistently performed better than those on diets containing the test ingredient. Snails on the control diet had higher mean clutch size value while those on 100% inclusion level of test ingredient recorded the least mean clutch size value across the mating groups. The incubation period of eggs laid by snails on control diet was lower than those on diets containing test ingredient inclusion. Eggs hatchability and hatchlings weights decreased with increasing levels of test ingredient inclusion. Results of growth traits of hatchlings showed that there was decreasing growth rate with increasing levels of test inclusion. However, snails on diets containing between 25% and 50% test ingredient inclusion compared favourably with those on control diet in terms of weight gain, final body weight, feed intake, feed conversion ratio and percent mortality across the mating groups. Based on the results of this study, it is recommended that sun-dried taro cocoyam meal can replace maize up to 50% in the diet of A. achatina without detrimental effects on reproductive traits of parents and growth traits of the F1. We however suggest that other methods of processing be applied to the cocoyam to allow for higher inclusion levels.

Litchi stink bug (Tessaratoma javanica) outbreak in Jharkhand, India, on litchi

The litchi stink bug Tessaratoma javanica (Thunberg) (Hemiptera: Tessaratomidae) is a minor insect pest of litchi (Litchi chinensis Sonn.) in India. Recently, an outbreak of litchi stink bug was observed in the Chotanagpur plateau of Jharkhand, India, during February–April 2011. A description of the outbreak is given in this report. Females were found to be highly fecund and caused severe damage to the litchi crop (>80%) in the region. Incubation period of eggs was found to be 12.80 days. The mean nymph population was 45.66 nymphs per 30-cm shoot length, and the maximum was159 nymphs, observed during March and April 2012 on litchi trees. The outbreak of the pest may be due to the migration of bugs from wild kusum (Schleichera oleosa (Lour.) Oken) plants (a host plant of the litchi stink bug) to the cultivated litchi crop. During the course of the investigation, two natural enemies were found on litchi stink bug, viz., Anastatus bangalorensis Mani & Kurian and Ooencyrtus sp. However, the natural parasitization by the parasitoids was very low, 3.5%. Considering the damage caused to the litchi crop in this region, the recent outbreak created an alarming situation for the pest management researchers of the country to develop suitable integrated pest management strategies in the near future. Otherwise this will become a major problem to the litchi growers as well as to industries associated with this delicious fruit in India.

Sublethal effects of pyriproxyfen, a juvenile hormone analogue, on Plutella xylostella (Lepidoptera: Plutellidae): life table study

The sublethal effects of pyriproxyfen (PYR, a juvenile hormone analogue) were investigated for two consecutive generations on life-history parameters, such as developmental time, pupal weight, fecundity, fertility and longevity of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). After topical application bioassay of third instar larvae, the LC25 and LC50 values (as sublethal doses) were determined to be 1.49 and 2.01 μg/μl, respectively. The results showed that the egg incubation period, larval and pupal duration times and oviposition period were increased in treated groups compared with the control (treated with distilled water). Pupal weight, adult longevity, fecundity and fertility were significantly reduced in the treatment groups compared with the control. Using the age-stage, two-sex life table analysis, we found that the intrinsic rate of increase (r), finite rate of increase (λ), gross reproduction rate (GRR) and net reproductive rate (R 0) significantly decreased while the mean generation time (T) and doubling time (DT) increased in two treatment groups compared with the control. In addition, administration of PYR induced morphogenetic abnormalities including untanned pupae, larval–pupal intermediates and various defective adults. The LC50 value was more effective on all of the above biological characteristics than the LC25 for both generations, although parents were more affected than the offspring. In general, our results revealed that PYR was highly effective against P. xylostella in the laboratory both directly (causing mortality) and indirectly (disruption of normal growth and development). We conclude that PYR is an excellent candidate for suppressing populations of P. xylostella through its sublethal effects.

Modeling the timing of spawning and hatching of shortnose sturgeon, Acipenser brevirostrum, in the Saint John River, New Brunswick, Canada

Timing of spawning and hatching of shortnose sturgeon, Acipenser brevirostrum , in the Saint John River, New Brunswick, Canada, was estimated using inverse prediction. We examined egg incubation periods at 5, 9, and 13 °C to back-calculate spawning dates. No larvae hatched at 5 °C. At 9 and 13 °C, hatching began after 18 and 8 days post fertilization, respectively. Lengths of yolk-sac larvae reared in the laboratory at 13–21 °C were used to develop a temperature-mediated Gompertz growth model. The inverted Gompertz model, predicting larval age from larval size and water temperature, was applied to 671, 164, and 746 larvae captured in the wild in 2008, 2009, and 2010, respectively. Estimated hatching distributions peaked in late May, and mean spawning events were predicted to occur in late April – early May (9 °C scenario) and middle to late May (13 °C scenario). Larval ages at the two sampling transects, 4.5 km apart, were similar, while catch per unit effort was lower downstream, indicating mortality during dispersal. Inverse prediction of larval ages provides fast and cost-effective estimates of the timing of spawning, hatching, and larval migration in the wild.

Effect of host plants on fitness traits and detoxifying enzymes activity of Helopeltis theivora, a major sucking insect pest of tea

Helopeltis theivora Waterhouse (Heteroptera: Miridae) is a major sucking insect pest of tea (Camellia sinensis) which feeds on a wide variety of alternative host plants. Feeding biology and fitness traits of H. theivora, on two alternative host plants, viz., Mikania micrantha (Asteraceae) and Psidium guajava (Myrtaceae), besides C. sinensis (Theaceae), were studied along with corresponding levels of xenobiotic defense enzymes. C. sinensis is the preferred host of H. theivora. The development time of H. theivora is significantly shorter on C. sinensis (13.3 ± 0.16 days) than on the two other hosts, M. micrantha (14.2 ± 0.22 days) and P. guajava (14.7 ± 0.23 days). Similarly, the fecundity (C. sinensis: 172.6 ± 4.5 eggs/female, M. micrantha: 128.6 ± 4.4 eggs/female, P. guajava: 118.7 ± 3.3 eggs/female), oviposition period (C. sinensis: 24.1 ± 0.7 days, M. micrantha: 22.5 ± 0.6 days, P. guajava: 21.7 ± 0.8 days) and hatchability (C. sinensis: 80.9 ± 1.9%, M. micrantha: 69.4 ± 1.6%, P. guajava: 64.1 ± 1.7%) are recorded to be significantly higher on C. sinensis. The age at reproductive maturity and egg incubation periods were lower on C. sinensis than on the two other host plants. Host-based variation in H. theivora fitness traits is interpreted in light of differential activity of three principal xenobiotic detoxifying enzymes, the general esterases (GEs), glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (CYPs). The activities of these enzymes in H. theivora were significantly enhanced when the insect fed on M. micrantha and P. guajava as compared with on C. sinensis.

Morphological, biological and molecular characteristics of bisexual and parthenogenetic Haemaphysalis longicornis

The reproductive mechanism of Haemaphysalis longicornis is quite different from many other animal species. In this article, several characteristics of parthenogenetic and bisexual populations of H. longicornis were analyzed, including some important micro-structures, synchronized life cycle feature and sequences of mitochondrial 16S rRNA gene. The results suggested even though many observations of the two populations were similar to each other, some important differences also existed. The genital apron of parthenogenetic females was wider than that of bisexual females. Parthenogenetic individuals (except engorged females) were significantly larger in weight than bisexual individuals (p<0.01; unfed nymph p<0.05); the difference of nymphal premoulting, female feeding and preoviposition, and egg incubation periods between the two populations were significant (p<0.01); hatch percentage of parthenogenesis was lower than that of bisexual population (69% and 73%, respectively); parthenogenetic individuals had a slightly longer development cycle than bisexual individuals (134 and 129days, respectively). Hybridization attempts failed between them. Comparing to the two strains of bisexual H. longicornis, parthenogenetic strain of H. longicornis inserted two nucleotides of thymine, though the genetic distance of 16S rDNA between the bisexual and parthenogenetic populations was 0. In order to clarify the relationships of the two reproductive populations of H. longicornis, the sequences of 16S rDNA of four strains of two other species were also analyzed. The divergence between Hebei and Xinjiang strains of Rhipicephalus sanguineus was 0, and the sequences were totally identical between them. The divergence between the two subspecies of Hyalomma asiaticum was 0.01. The results indicated that the relationship between bisexual and parthenogenetic H. longicornis was certainly closer than that between subspecies, but farther than that between the same reproductive populations of conspecies.

Determination of optimum temperature and photoperiod for mass production of Oxya hyla hyla (Serville)

Insects are natural food for many vertebrates. Being nutritionally rich, acridids can be used to produce high quality feed for livestock industries. For a sustainable supply for the feed manufacturing companies, a huge acridid biomass must be obtained on a regular basis. Therefore, for successful acridid farming, a laboratory rearing system in semi-controlled conditions is proposed to produce a huge acridid biomass. Experiments were conducted to determine a favorable temperature and photoperiod for rearing the chosen multivoltine species, i.e. Oxya hyla hyla. For this purpose nymphal mortality, growth rate, fecundity, fertility, and adult dry weight were determined. The results revealed that, at 35 ± 2 °C with a L:D photoperiod of 12:12, fecundity and fertility were maximum, while nymphal mortality, egg incubation period, nymphal duration, adult life span, and adult dry weight were favorable. It was concluded that 35 ± 2 °C with a photoperiod of 12:12 is suitable for mass production of Oxya hyla hyla in acridid farms.

The Impact of Temperature on Biological Aspects and Life Table ofHarmonia axyridis(Pallas) (Coleoptera: Coccinellidae)

ABSTRACT The impacts of temperature on Harmonia axyridis and its potential as a control agent of Cinara atlantica, the Carolina conifer aphid, were evaluated. The experiments were conducted with eggs from field-collected adults. Each egg batch was kept at 15 °C, 20 °C and 25 ° C, 70% RH and 12:12 h. L:D. After hatching, the larvae were reared individually until adult emergence and all insects were kept under the same conditions. The mean period of egg incubation, total developmental time and egg viability were longer at 15 °C that than at the other 2 temperatures. Survival was 100% for all the larval, pre-pupal and pupal stages. The longevity was longer at 15 °C and 20 °C than 25 °C The mean number of eggs produced was significantly higher at 15 °C than at the other 2 temperatures. The post-oviposition period increased with increasing temperature. The highest specific fertility was recorded at 15 °C, followed by 25 °C and 20 °C, respectively. The net reproductive rate was higher at 15 °C than at the 2 hig...

Biological Study of Plutella xylostella (L.) (Lep: Plutellidae) and It’s Solitary Endoparasitoid, Cotesia vestalis (haliday) (Hym. Braconidae) under Laboratory Conditions

Plutella xylostella (L.) (Lep: Plutellidae), is a destructive pest of brassicaceous crops in the world. Cotesia vestalis (Haliday) is one of most important biological control agents of P. xylostella in the world and Iran. Both of P. xylostella and C. vestalis biology were carried out in laboratory condition. Results showed that development time of immature stages of P. xylostella including egg, Instar I, Instar II, Instar III, Instar IV, prepupa, pupa were 2.39 +/- 0.17, 2.18 +/- 0.17, 2.06 +/- 0.28, 2.14 +/- 0.14, 2.54 +/- 0.12, 0.40 +/- 0.12 and 4.23 +/- 0.23 days, respectively. Longevity of female and male were 28.26 +/- 0.05 and 30.22 +/- 0.05 days. By dissecting the parasitized larvae, the egg incubation period of C. vestalis was recorded 1.73 +/- 0.06 days. In long-term oviposition trials, females laid eggs on P. xylostella larvae for up to 10 days. Larval development of the parasitoid in host only required 6.47 days: the first instar larva required 3.25 +/- 0.047 days; the second instar larva needed 2.78 +/- 0.1 days and the third instar larvae exited the host and pupated in, 0.4 +/- 0.07 days. Prepupal and pupal period of wasp were 1.9 +/- 0.06 and 2.13 +/- 0.09 day, respectively. Unmated female and male longevity of wasp were 16.83 +/- 0.37, 16.25 +/- 0.17 and sex ratio is male-biased. When a mixed group and isolated of instars were presented for parasitoid, the 2nd and 3rd instar larvae were so preferred and the 4th instar was less attractive for selection. In choice experiment, the percentage parasitism of 2nd, 3rd and 4th instars was 78.58, 69.94 and 4.36%, respectively. The rapid oviposition rate, short life duration and high percentage parasitism increases parasitoid potential for suppression of host population. Present results suggest that C. vestalis has considerable potential as a biological control agent for P. xylostella.

Evolution of reproductive life histories in island birds worldwide

Island environments typically share characteristics such as impoverished biotas and less-seasonal climates, which should be conducive to specific adaptations by organisms. However, with the exception of morphological studies, broad-scale tests of patterns of adaptation on islands are rare. Here, I examine reproductive patterns in island birds worldwide. Reproductive life histories are influenced by latitude, which could affect the response to insularity; therefore, I additionally test this hypothesis. Island colonizers showed mostly bi-parental care, but there was a significant increase in cooperative breeding on islands. Additionally, I found support for previous suggestions of reduced fecundity, longer developmental periods and increased investment in young on islands. However, clutch size increased with latitude at a rate nearly five times faster on the mainland than on the islands revealing a substantially stronger effect of insularity at higher latitudes. Latitude and insularity may also interact to determine egg volume and incubation periods, but these effects were less clear. Analyses of reproductive success did not support an effect of reduced nest predation as a driver of reproductive change, but this requires further study. The effect of latitude detected here suggests that the evolutionary changes associated with insularity relate to environmental stability and improved adult survival.

PENGARUH LAMA PERIODE KERING DAN INTENSITAS CURAH HUJAN TERHADAP PENETASAN BELALANG KEMBARA (LOCUSTA MIGRATORIA MANILENSIS MEYEN)

Effect of Dry Period and Rainfall Intensity on Emergence of the Migratory Locust (Locusta migratoria manilensis Meyen). Dry period and rainfall intensity were simulated experimentally to determine their effects on nymph emergence of the migratory locust (Locusta migratoria manilensis Meyen) (Orthoptera: Acrididae). The experiment was conducted in a factorial set up with two factors, i.e. dry periods (1, 2, 4, 8, and 12 week interval of watering) and rainfall intensity (80, 140, 200, and 260 mm/month). Locust nymphal emergence and time required to emerge after the watering were recorded and analyzed. Results of the experiment indicated that dry periods and rainfall levels affected nymphal emergence of the migratory locust. Interaction between dry periods and rainfall levels, however, were statistically not significant (F-value = 0,69 and P-value = 0,7526). Nymphal emergences of L. m. manilensis tended to be higher on soils that were watered less frequently. Similarly, locust emergences were also higher for the soil with lower rainfall intensity (received less amount of watering). At the 80 mm/month rainfall level, 20 – 105,5 days period (egg incubation period) were required before the locust emergence. Incubation period of the eggs was significantly higher as the breeding media (soil) were watered less frequently. On the other hand, time required for the egg to emerge as nymphs was relatively similar regardless of the dry period levels. All eggs emerged 14 – 15,5 days after watering.