Wasp Emergence Research Articles

Host Species Affects Gut Microbial Community and Offspring Developmental Performances in the Pupal Parasitoid Chouioia cunea Yang (Hymenoptera: Eulophidae).

Chouioia cunea are known to exploit in varying degrees a wide range of lepidopteran species and its offspring development may vary with host species. This study examined its preimaginal development and larval gut microbiota in parasitizing five folivorous lepidopteran hosts including Hyphantria cunea (referred to thereafter as CcHc), Antherea pernyi (CcAp), Helicoverpa armigera (CcHa), Spodoptera exigua (CcSe), and Spodoptera frugiperda (CcSf). Though rates of parasitism and offspring eclosion did not change with host species, the development period and number of offspring eclosed varied with hosts, with the shortest period in CcSf and the highest number from CcAp. For offspring larval gut microbiota, though phylum Proteobacteria was dominant for attacking CcAp, Firmicutes was so for the other hosts. All microbial genera except Enterococcus were less abundant for CcSf than the other hosts. The database-based predictions indicate a significant positive correlation between Cutibacterium and Aureimonas with the relative number of wasp emergence, while Blastomonas exhibits a strong positive association with the developmental period. Our results imply the potential relevance of the gut microbial community in offspring larvae to host species attacked by C. cunea.

Nesting and mating behaviours, and the development time of three solitary digger wasps of the genus Ammophila (Hymenoptera: Sphecidae)

Abstract Nesting and mating behaviours and the development time of Ammophila clavus (Fabricius), Ammophila globifrontalis Q.Li & Ch.Yang, and Ammophila laevigata F.Smith from Vietnam are presented. All three dig their nests in the ground. The nest entrance is round. The nest burrow is nearly vertical and ends with an elliptical cell. The cell contains 1–2 caterpillars. The egg is usually glued on the third abdominal segment of prey. The three wasps temporarily close their nest burrows just below the entrance when provisioning, but permanently close them above or at the nest cells when full provision is complete. As the last stage of nest construction, the nest entrance is camouflaged with small sticks and several pebbles. Males of both Ammophila clavus and Ammophila laevigata patrol nesting areas, pursue females searching for their nest sites, pounce upon them, and mate with them on the ground. The development time from egg to the emergence of adult wasps is more than one month, males always emerging before females. The nesting behaviour of the three Ammophila species is compared and discussed.

Phenology model development for Neodryinus typhlocybae: Evaluation of phenological synchrony with its host, Metcalfa pruinosa

The invasive species Metcalfa pruinosa has inflicted significant economic losses in various European and Asian regions. To combat this pest, the parasitoid wasp Neodryinus typhlocybae has been effectively introduced in Europe. Despite its success, research on the field occurrence patterns of N. typhlocybae, particularly its phenology, remains scarce. This study aims to develop a degree-day model for predicting the adult emergence of N. typhlocybae from overwintering cocoons and to assess the phenological synchrony between N. typhlocybae adults and the nymphal stages of M. pruinosa in Korea. In this study, we estimated the thermal parameters of N. typhlocybae under field temperatures and six constant temperatures (13.92, 17.71, 18.53, 20.53, 22.78, and 24.03 °C) conditions. The lower developmental temperature was estimated using the values of the coefficient of variation for the cumulative degree days of emerged individual adults. The estimated lower developmental threshold temperature was 12.3 °C. With this developmental threshold, a degree-day model was developed, and this model well-predicted emergence in field conditions. By simulating this developed model with the actual occurrence of the nymphal stages of its host, M. pruinosa, adult wasp emergence was estimated to be 1.5 weeks later than the first instar nymph of the host but faster than other nymphal stages of M. pruinosa. Thus, the findings in this study would be helpful in determining the possibility of establishing N. typhlocybae and improving the management efficiency of M. pruinosa.

Arsenophonus: A Double-Edged Sword of Aphid Defense against Parasitoids.

It is widely accepted that endosymbiont interactions with their hosts have significant effects on the fitness of both pests and beneficial species. A particular type of endosymbiosis is that of beneficial associations. Facultative endosymbiotic bacteria are associated with elements that provide aphids with protection from parasitoids. Arsenophonus (Enterobacterales: Morganellaceae) is one such endosymbiont bacterium, with infections being most commonly found among the Hemiptera species. Here, black cowpea aphids (BCAs), Aphis craccivora Koch (Hemiptera: Aphididae), naturally infected with Arsenophonus, were evaluated to determine the defensive role of this bacterium in BCAs against two parasitoid wasp species, Binodoxys angelicae and Lysiphlebus fabarum (both in Braconidae: Aphidiinae). Individuals of the black cowpea aphids infected with Arsenophonus were treated with a blend of ampicillin, cefotaxime, and gentamicin (Arsenophonus-reduced infection, AR) and subsequently subjected to parasitism assays. The results showed that the presence of Arsenophonus does not prevent BCAs from being parasitized by either B. angelicae or L. fabarum. Nonetheless, in BCA colonies parasitized by B. angelicae, the endosymbiont delayed both the larval maturation period and the emergence of the adult parasitoid wasps. In brief, Arsenophonus indirectly limits the effectiveness of B. angelicae parasitism by decreasing the number of emerged adult wasps. Therefore, other members of the BCA colony can survive. Arsenophonus acts as a double-edged sword, capturing the complex dynamic between A. craccivora and its parasitoids.

Direct and Indirect Competitive Interactions between Ooencyrtus nezarae and Paratelenomus saccharalis Parasitizing Megacopta cribraria Egg Patches.

The present study investigated egg parasitoid interspecific interactions between a generalist, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and a specialist, Paratelenomus saccharalis Dodd (Hymenoptera: Platygastridae) in a laboratory setting using kudzu bug (Megacopta cribraria Fabricius, (Hemiptera: Plataspidae)) eggs as their shared host. Three experiments were conducted to evaluate the emergence of wasps from parasitized hosts after the simultaneous and sequential release of wasps, monitor aggressive behavior of P. saccharalis, and quantify intraguild predation of O. nezarae larvae on heterospecific P. saccharalis larvae. Results showed that total host egg parasitism was higher when both wasps were released simultaneously than if wasps were released sequentially. Ooencyrtus nezarae produced more total offspring than P. saccharalis in all sequential/simultaneous treatments but produced male offspring in most cases. In the aggressive behavioral experiment, specialist, P. saccharalis used head butting to fight O. nezarae, but no other aggressions were observed. In an experiment examining intraguild predation, O. nezarae was able to develop in host eggs parasitized by P. saccharalis four days earlier, acting as a superior larval competitor. These findings shed light on the potential interspecific interactions between O. nezarae and P. saccharalis, which may determine their relative abundance and influence their compatibility in kudzu bug biological control programs.

The Association between the Distribution of Resin Beads and the Emergence of Sirex noctilio on Red Pine in North America.

This study examined the relationships of the abundance and distribution of resin beads (signs of Sirex noctilio parent female ovipositor activity) with the abundance and distribution of emerging progeny of S. noctilio, S. nigricornis and their parasitoid Ibalia leucospoides. S. noctilio is native to Europe and is an invasive pest of pines in the Southern Hemisphere and North America; S. nigricornis is native to North America and is a secondary pest of dying pines. I. leucospoides is a parasitoid that has been widely deployed for biological control of S. noctilio. This study aimed to determine if the distribution of resin beads is associated with the height, diameter, or cardinal direction on red pines, Pinus resinosa, as well as the distribution of wood wasp and parasitoid emergence. Our results showed that among log sections taken at five heights, resin beads were most abundant on the north, east, and south sides of logs and mid log at 4.5 m above the ground. Emergence of S. noctilio was most abundant only from logs with more than five resin beads per square meter, while diameter and height were not contributing factor. None of variables evaluated (resin bead densities, height, and diameter) had significant effects on the emergence of S. nigricornis and I. leucospoides. These findings help clarify the biological significance of resin beads as indicators of S. noctilio colonization of host trees in North America.

Developmental timing of extreme temperature events (heat waves) disrupts host-parasitoid interactions.

When thermal tolerances differ between interacting species, extreme temperature events (heat waves) will alter the ecological outcomes. The parasitoid wasp Cotesia congregata suffers high mortality when reared throughout development at temperatures that are nonstressful for its host, Manduca sexta. However, the effects of short‐term heat stress during parasitoid development are unknown in this host–parasitoid system.Here, we investigate how duration of exposure, daily maximum temperature, and the developmental timing of heat waves impact the performance of C. congregata and its host¸ M. sexta. We find that the developmental timing of short‐term heat waves strongly determines parasitoid and host outcomes.Heat waves during parasitoid embryonic development resulted in complete wasp mortality and the production of giant, long‐lived hosts. Heat waves during the 1st‐instar had little effect on wasp success, whereas heat waves during the parasitoid's nutritionally and hormonally critical 2nd instar greatly reduced wasp emergence and eclosion. The temperature and duration of heat waves experienced early in development determined what proportion of hosts had complete parasitoid mortality and abnormal phenotypes.Our results suggest that the timing of extreme temperature events will be crucial to determining the ecological impacts on this host–parasitoid system. Discrepancies in thermal tolerance between interacting species and across development will have important ramifications on ecosystem responses to climate change.

Ovipositional preference of Trichogramma dendrolimi and Trichogramma ostriniae strains from Myanmar on different host egg ages of Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae)

ABSTRACT Trichogramma (Hymenoptera: Trichogrammatidae) wasps are the most successfully biological control agents against the Asian corn borer, Ostrinia furnacalis (Guenée). To progress with biological control of this pest in Myanmar, we investigated the performances of three strains of T. ostriniae and two strains of T. dendrolimi on O. furnacalis eggs of different ages (6–12-, 12–24-, 24–36- and 36–48-hr) under choice and no-choice conditions. The ovipositional preference was significantly different among these tested strains. Two T. dendrolimi strains from Southern Shan State of Myanmar and China exhibited a strong preference on the younger, 6–12-hr-old host eggs. The two indigenous T. ostriniae strains showed no difference in ovipositional preference for the first three ages (6–12-, 12–24- and 24–36-hr), however, the preference of T. ostriniae from China was significantly higher on the 12–24-hr-old eggs. None of the strains tested strongly preferred the 36–48-hr-old eggs. Under no-choice conditions, all tested ages were accepted by all Trichogramma strains, however, the T. dendrolimi strains parasitised significantly fewer eggs with increasing host age. Wasp emergence rate was also higher (94%) from the 12–24-hr-old eggs while immature developmental time was significantly prolonged on the 6–12-hr-old eggs. Two T. ostriniae strains from Southern Shan State had a broader host age preference with higher parasitism, being 32 eggs/female, and produced a greater number of progeny (∼43). These two T. ostriniae strains were identified as the most effective Trichogramma strains of O. furnacalis. The present study provides valuable information for a potential biological control programme of this maize key pest in Myanmar.

The transgenerational consequences of maternal parasitism for aphid life history and suitability for subsequent parasitism.

Aphids parasitized in later instars can give birth to several nymphs before their reproduction is curtailed by the developing parasitoid. We examined the life histories of Aphis fabae Scopoli born to mothers parasitized by Lysiphlebus fabarum Marshall, and their suitability as subsequent hosts, to test the 'fecundity compensation' hypothesis. Maternal parasitism negatively impacted life history parameters, resulting in reduced estimates of population increase (rm, R0, and λ), and increased generation time (GT) and doubling time (DT). These impacts were greater when the larva developing in the mother turned out to be female rather than male, and greater still when mothers were superparasitized. Maternal parasitism produced aphids with shorter hind tibia (HTL), at birth and at maturity, but their developmental time was unaffected. Although female L. fabarum readily accepted such aphids for oviposition, rates of mummification and wasp emergence were lower, and more so when the maternal parasitoid was female. The resulting parasitoids took longer to develop than progeny from control wasps, had shorter HTLs, lower egg loads, smaller eggs, and produced fewer mummies with lower rates of adult emergence, all differences that were more pronounced when the maternal parasitoid was female. The progeny of these wasps exhibited similar impairments to these biological parameters as their parents, demonstrating that the negative impacts of development in maternally parasitized hosts extended for at least two generations. Thus, our results do not support fecundity compensation, but suggest that any benefits of post-parasitism reproduction will be offset by reduced fitness in both aphid progeny and the parasitoids that develop in them.

Ixodiphagus hookeri wasps (Hymenoptera: Encyrtidae) in two sympatric tick species Ixodes ricinus and Haemaphysalis concinna (Ixodida: Ixodidae) in the Slovak Karst (Slovakia): ecological and biological considerations

Ixodiphagus endoparasitoid wasps are natural tick enemies that can reduce their abundance. In this study, we investigated the presence of Ixodiphagus hookeri in Haemaphysalis concinna and Ixodes ricinus ticks in the Slovak Karst (southern Slovakia) and analysed the ecological and physiological relationships in the parasitoid-host system. Unfed H. concinna and I. ricinus nymphs harvested from vegetation were fed on rabbits. The engorged specimens were kept at 25 °C and 75% RH until the emergence of the adult wasps. For the first time in Europe, we found the presence of I. hookeri in two species of ticks collected in the same locality and compared their development in these tick species. The prevalence of wasps in H. concinna and I. ricinus during their spring activity was estimated at 10.64% and 27.78%, respectively. The presence of the wasps did not affect the duration of nymph feeding. Engorged wasp-infected ticks achieved higher body mass than non-infected specimens. In both tick species, there were no differences in the length of the development period and the number and sex ratio of adult I. hookeri. The analysed indicators and characteristics of the I. hookeri wasp-tick system can be used in research on tick control.

Efficacy and emergence of parasitic wasps that attack herbivorous insects on maize and its relatives in their region of origin

Maize (Zea mays subsp. mays), an important cereal crop worldwide, was domesticated directly from the annual teosinte (Zea mays subsp. parviglumis), and teosintes originated from gamagrass (Tripsacum) plants. Some herbivorous insects of maize began their association on Tripsacum; however, little is known about the interaction between these herbivores and their parasitoids in this ancestral Tripsacum habitat. A field experiment was conducted in the Mesoamerican region of origin of maize, using sentinel eggs of the hopper Dalbulus quinquenotatus on Tripsacum dactyloides, and eggs of the insect pest Dalbulus maidis on annual teosinte, landrace maize, and modern maize. A community of egg parasitoids formed by Anagrus naulti (Mymaridae), Paracentrobia sp., and Pseudoligosita sp. (Trichogrammatidae) was found attacking eggs of both species of hoppers on the tested host plants. The largest abundance of parasitoids adult emergence and rate of parasitism was found in D. quinquenotatus eggs laid on T. dactyloides. The rate of parasitism was similar for the other three treatments: D. maidis on teosinte, landrace maize, and modern maize. In the D. quinquenotatus-Tripsacum treatment, D. maidis-annual teosinte treatment, and D. maidis-hybrid maize treatment more Paracentrobia sp. adults emerged than A. naulti adults. These results suggest that the interaction between hoppers and their egg parasitoids occurs on Tripsacum plants, and probably has been in place since before maize domestication.

Differing thermal sensitivities in a host–parasitoid interaction: High, fluctuating developmental temperatures produce dead wasps and giant caterpillars

Abstract Insect parasitoids, and the arthropod hosts they consume during development, are important ecological players in almost all environments across the globe. As ectothermic organisms, both parasitoid and host are strongly impacted by environmental temperature. If thermal tolerances differ between host insect and parasitoid, then the outcome of their interaction will be determined by the ambient temperature. As mean temperatures continue to rise and extreme temperatures become more frequent, we must determine the effect of high temperature stress on host–parasitoid systems to predict how they will fare in the face of climate change. The majority of studies conducted on host–parasitoid systems focus on either performance under constant temperature or a fixed metric of thermal tolerance (CTmax) for individual organisms. However, performance at constant temperatures is not predictive of performance under ecologically relevant, fluctuating temperatures and measurements of thermal thresholds provide little information regarding the effects of temperature throughout development. We address this by testing the effects of increasing mean temperature in both constant and fluctuating (±10°C) environments throughout development on the performance of the parasitoid wasp Cotesia congregata and its lepidopteran larval host, Manduca sexta. The growth of M. sexta was influenced by mean temperature, diurnal fluctuations and parasitization status. Caterpillar growth rate increased with increasing mean temperature, but decreased in response to diurnal fluctuations and parasitization by C. congregata wasps. Wasp survival decreased with increasing mean temperature and with diurnal fluctuations. The effect of diurnal fluctuations was stronger at higher mean temperatures. Diurnal fluctuations at our highest mean temperature treatment (30 ± 10°C) resulted in complete wasp mortality, and parasitized hosts displayed abnormal physiology, wherein they failed to exhibit wasp emergence, did not enter the prepupal stage, continued to feed and grew up to twofold larger than a normal, unparasitized caterpillar. Our results indicate hosts and parasitoids in this system have different thermal tolerances during development; the parasitoid wasp suffered complete mortality at a temperature regime that is mildly stressful for the unparasitized caterpillar host species. Our findings suggest C. congregata will suffer more severely under increasing temperatures than M. sexta, with cascading trophic and ecological effects. A free Plain Language Summary can be found within the Supporting Information of this article.

Color, odor, and species preferences of Copidosoma bakeri to prospective cover crops to enhance control of cutworms

AbstractCutworms (Lepidoptera: Noctuidae) are economically important pests of multiple field crops, but are difficult to control with insecticides. Biological control with native parasitoids may offer a sustainable alternative for pest management. Cover crops improve the availability of resources required by parasitoids to increase their effectiveness as biocontrol agents. Copidosoma spp. (Hymenoptera: Encyrtidae) have the potential to control several species of cutworms in the Canadian Prairies. However, their foraging preferences for non‐host food items are unknown. In this study, we tested flower color and odor preferences of Copidosoma bakeri (Howard) across nine potential cover crop species and investigated how these resources affect survival and longevity of the female wasps. Results indicated that the wasps were most attracted to plants with yellow flowers in the family Brassicaceae (i.e., camelina, mustard, and canola). In multiple‐choice tests, the wasps preferred camelina over all other flower species, and showed an intermediate preference for mustard and canola. In dual‐choice tests with color paper, the wasps preferred yellow over white, and the light yellow of camelina over the bright yellow of canola and mustard, whereas they showed a preference for the odors of mustard and canola. Life expectancy was increased when the wasps were provided floral resources compared to the absence of a food source. Later planting dates and mixed‐species plantings of cover crops resulted in flowering times that better coincided with native wasp emergence. Camelina is known to suppress weeds and may be used as a habitat management tool for enhancing parasitism of cutworms by C. bakeri in the Canadian Prairies. However, further testing is needed to achieve late flowering well into August and early September and to ensure planting additional Brassica spp. does not attract more late‐season pests to cash crops such as canola.

Rearing temperature and parasitoid load determine host and parasitoid performance in Manduca sexta and Cotesia congregata

1. Temperature strongly influences the rates of physiological processes in insects, including the herbivore Manduca sexta and its larval endoparasitoid Cotesia congregata. Parasitisation by C. congregata decreases the growth and consumption of food by larval M. sexta. However, the effects of temperature on parasitised caterpillars and the developing wasp larvae are largely unknown.2. In this study, parasitised and unparasitised caterpillars were reared at three constant temperatures (20, 25 and 30 °C) throughout larval development. Caterpillar mass gain and consumption were monitored daily until wandering (unparasitised control group) or wasp emergence (parasitised group) was observed. Development time and survival to emergence were measured as metrics of parasitoid performance.3. Parasitised M. sexta developed more slowly than unparasitised controls, but had similar cumulative consumption until the terminal instar. Parasitised caterpillars with relatively large parasitoid loads had higher rates of consumption and growth than those with smaller loads. Both temperature and parasitoid load strongly affected wasp success. Mean development time to wasp emergence increased with low temperatures and with large loads. The combination of warm temperature and large parasitoid loads greatly reduced wasp survival.4. These results demonstrate the interactive effects of rearing temperature and parasitisation on host consumption and growth rates throughout larval development. In addition, wasp performance was affected by the interaction of temperature and parasitoid load size. High temperatures alter the dynamics of the interaction between the parasitoid and its caterpillar host, which could have far‐reaching impacts as the global temperatures continue to rise.

Effects of host species and host age on biological parameters of Anagrus virlai (Hymenoptera: Mymaridae), an egg parasitoid of Dalbulus maidis (Hemiptera: Cicadellidae) and Peregrinus maidis (Hemiptera: Delphacidae)

Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) and Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae) are important pests for maize production in America. Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) is a potential biological control agent for both hopper species. We provide information on the effects of size, age and host species on the time of development, parasitism and emergence, and morphometry of A. virlai. Additionally, we evaluate if A. virlai females can discriminate between the eggs of both host species using a Y-tube olfactometer. The wasps were reared in breeding chambers under controlled conditions, and one, three and five days-old eggs of D. maidis and P. maidis were used for bioassays. Anagrus virlai developed in eggs from the three age classes of both hopper species; however, the number of parasitized eggs and emergence of wasps was significantly higher on eggs of D. maidis than on those of P. maidis. Wasps that emerged from D. maidis eggs presented larger size compared to those reared on P. maidis eggs. Host species not only influenced the parasitism, emergence, and size of the wasps, but also development time. In olfactometric tests, A. virlai chose maize leaves containing D. maidis eggs, instead of those containing P. maidis eggs. Our results show that A. virlai, formerly known as generalist parasitoid, would only use the planthopper P. maidis as an occasional host.

Tracking seasonal emergence dynamics of an invasive gall wasp and its associated parasitoids with an open-source, microcontroller-based device

The invasive Asian chestnut gall wasp, Dryocosmus kuriphilus (Hymenoptera: Cynipidae), is one of the most economically important pests of chestnut forest systems. Control is either based on the use of pesticides or the release of the parasitoid Torymus sinensis (Torymidae) for classical biological control of the pest. Both approaches require frequent monitoring of wasp emergence patterns, usually by recording adult emergence from samples of galls stored in dark boxes. Here, we have improved this monitoring method by developing and evaluating a microcontroller-based device. Cages in which galls were placed were modified by insertion of a turntable, which automatically separates wasps emerging at different times. We used this device to monitor the seasonal emergence of D. kuriphilus, its coevolved parasitoid T. sinensis and newly associated native parasitoids from fresh or overwintered chestnut galls formed in 2013 and 2014. In summer, native parasitoids (3.6 and 5.8% of 2-year parasitism) associated with current-year chestnut galls started emerging before the gall wasp and only partially overlapped with D. kuriphilus emergence. After overwintering, in the spring of the following year, T. sinensis (4.3 and 5.5% of 2-year parasitism from overwintered galls) emerged earlier than indigenous parasitoids (1.6 and 4.8%) and indicated potential for D. kuriphilus control. Overall, 14 species of native parasitoids belonging to five families were recorded from fresh and overwintered galls. We provide the schematic and the programming codes for this new device and propose that this automatic device be used to better track the flight periods of D. kuriphilus and its parasitoids.

Behavioral and Biological Effects of Exposure to Tuta absoluta (Lepidoptera: Gelechiidae) Sex Pheromone on Several Trichogramma (Hymenoptera: Trichogrammatidae) Populations.

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of tomato worldwide. Biological control of the pest using Trichogramma (Hymenoptera: Trichogrammatidae) wasps can be combined with other practices such as use of synthetic sex pheromones for mating disruption or mass trapping programs. In this study, effects of T. absoluta sex pheromone on behavioral responses and fertility life table parameters of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae), Wolbachia-uninfected (W-) Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae), and Wolbachia-infected (W+) T. brassicae were investigated under laboratory conditions. Female wasps of T. evanescens and T. brassicae (W+) were attracted to the pest synthetic sex pheromone (around 62%) and calling virgin female moths (around 75%) and their responses were affected by the wasp age and temperature. Exposure to the host synthetic sex pheromone significantly reduced the percentage of adult emergence, longevity, and fecundity of female wasps, as well as the time spent to find a mate and duration of mating. However, tested populations were not affected similarly. Despite the laboratory tests, greenhouse experiments showed that the wasps were not caught in the traps baited with T. absoluta synthetic sex pheromone. Complementary studies are needed to precisely determine possible interference between pheromone application and releasing Trichogramma Westwood (Hymenoptera: Trichogrammatidae) wasps to achieve a successful integrated control of T. absoluta.

Host suitability of the Mediterranean flour moth for rearing Meteorus pulchricornis (Hymenoptera: Braconidae), a polyphagous endoparasitoid of pest lepidopteran larvae

We investigated the host suitability of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) for a polyphagous koinobiont endoparasitoid Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae), a common natural enemy of various pest lepidopteran larvae. The estimated probability of adult wasp emergence was 80% or higher when eggs were laid in nearly fully grown larvae of E. kuehniella (fresh weight, > 20.0 mg). The body size of emerged adult wasps increased with the initial weight of the host larvae at oviposition. The fresh weight of adult wasps reared on E. kuehniella was approximately 60% of that when reared on a natural host Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), and the lifetime fecundity of wasps reared on E. kuehniella was approximately half of that when reared on S. litura. Ephestia kuehniella was shown to be a positive host candidate for the mass rearing of M. pulchricornis, but further investigation is needed to increase the body size of wasps for more practical use of this species as a biocontrol agent.

Development of Galls in Eucalyptus Due to Infestation of Leptocybe invasa and Its Effects on Growth of Seedlings.

Leptocybe invasa Fisher & LaSalle (Hymenoptera : Eulophidae), commonly known as blue gum chalcid wasp, is a major gall making insect species of eucalyptus, causing serious damage to seedlings in nursery stage. An insectary/nursery of eucalyptus was developed at this Institute to study the stages of gall development, number of galls formed with the age of seedling and effects of galls on the growth of seedling. Results revealed that there are five distinct stages of gall development, first stage initiates by the insertion of eggs on the epidermis of soft young leaves, petioles and stems and final stage ends with the emergence of adult wasps from galls through exit holes. It was observed that the development of galls start after one month age of seedlings, and there was significant (P<0.05-P<0.01) variation in growth (height and collar diameter), number of galls in leaves, petioles and stems, and total number of galls/seedling in respect of age. The data clearly exhibited that one month old seedlings were free from the attack of L. invasa as because there was complete absence of galls. Further, it was recorded that seedlings growth (height and collar diameter) was affected by the development of galls, minimum growth was recorded in case of maximum galls developed whereas less galls were noticed for maximum growth of seedlings. There was an inverse relationship exists between seedling growth and development of galls. The practical application of findings was discussed in the light of the present observations.

Adaptive phenology of Ficus subpisocarpa and Ficus caulocarpa in Taipei, Taiwan

Insect pollination is the main strategy used by Angiosperm plants to transport pollen to another individual. The interaction between entomophilous plants and their pollinators is often mutualistic, with many species pairs being interdependent. In obligate pollination mutualism, the plant relies on its partner for pollination, whereas the pollen vector relies on plant resources. In the mutualism between Ficus (Moraceae) and the fig wasps (Hymenoptera, Agaonidae), the plant provides oviposition sites to its exclusive pollinator, which has an extremely short lifespan (a maximum lifespan of few days). This study examined how fig trees maintain their associated pollinator populations by conducting a 45-month phenological survey of 27 and 64 trees belonging to the species Ficus caulocarpa and F. subpisocarpa in Taipei, Taiwan. The observations indicated that the trees produce figs year-round with no clear seasonal pattern, and are not affected by meteorological factors. On average, about 30% of the trees of both species were bearing figs during the survey. The duration of the fig development was longer during the winter-spring period than during the summer-fall period. The trees displayed strong asynchrony among trees in the population but each crop was synchronous within a tree. However, after wasp emergence, crops lost their synchrony with part of the figs ripening within few days whereas some figs only ripened eight weeks later for F. subpisocarpa and four weeks later for F. caulocarpa. This study also discusses the implications of fig frugivory and mutualism.