Borer Eggs Research Articles

Parasitic performance of Trichogramma japonicum Ashmead on eggs of rice moth and rice stem borer : a comparative study

The present investigation on the parasitic potential of T. japonicum was undertaken during the year 2019-20 at the Bio-control Laboratory, Department of Agricultural Entomology, Navsari Agricultural University, Navsari (Gujarat). The results showed that the parasitic potential (F0) of T. japonicum was maximum (82.65 ± 6.86%) on Corcyra eggs as compared to rice yellow stem borer eggs (24.11 ± 3.37%). Similarly, the egg parasitization (F1) of T. japonicum on Corcyra eggs was comparatively higher (83.15 ± 5.06%) than that on yellow stem borer eggs (25.68 ± 3.60%). Moreover, the observed difference in parasitic potential of T. japonicum on Corcyra and Scirpophaga incertulas for both generations was found highly significant during the present investigation. The conclusion of the present investigation suggested that the natural host, the Yellow Stem Borer (YSB), could serve as a viable means for recycling the nucleus culture as well as amplifying the parasitic capabilities of T. japonicum during mass production program. Moreover, these findings could hold significant value in assessing the parasitic behavior of YSB when T. japonicum is introduced into paddy fields.

Natural Control of Sugarcane Top Borer Scirpophaga excerptalis Walker (Crambidae: Lepidoptera) by Its Egg Parasitoids

The sugarcane shoot borer (Scirpophaga excerptalis) is an herbivorous insect that primarily infests sugarcane plants, leading to the development of dead heart symptoms. This study aimed to investigate the contribution of egg parasitoids in mitigating the occurrence of dead heart caused by S. excerptalis infestation. The research was conducted in Asembagus and Malang, East Java, Indonesia. The samples collection of shoot borer eggs were done twice in Asembagus, and three times in Malang. The collected eggs were examined to determine the percentage of parasitism, and the emerged parasitoids were identified. The infestation level of shoot borers was evaluated by counting the dead heart symptoms within 5 m2 observation units, comprising 18 and 15 units in Asembagus and Karangploso, respectively. Three species of parasitoids, namely Telenomus sp., Trichogramma chilonis, and Tetrastichus sp., were found to parasitize S. excerptalis eggs. The average parasitism levels by Telenomus sp., T. chilonis, and Tetrastichus sp. were 74% (ranged: 50-100%), 0.6% (ranged: 0-4.4%), and 14.3% (ranged: 0-100%), respectively. Telenomus sp. was the predominant egg parasitoid observed in all observations at both sites. There was an inverse relationship between the mortality of shoot borer eggs by parasitoids and the occurrence of dead heart symptoms. Higher levels of parasitism were associated with reduced dead shoot symptoms. The natural control of S. excerptalis through the complex of egg parasitoids holds a promise for effective management of sugarcane shoot borers and promoting sustainable agriculture.

Functional Response and Parasitism rate of Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae), a Parasitoid of Eggs of Sugarcane Borer.

The evaluation of parameters such as functional response and parasitism rates is essential for the choice and use of a control agent, which contributes to a positive or negative outcome of Biological Control. Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), commonly called sugarcane borer, is the main pest of the sugarcane crop and its management can be done by the parasitoid Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae), which attacks the egg stage of the pest before damage is done to the crop. To better understand this host/parasitoid relationship, the functional response and parasitism rate of T. galloi in 0.4:1 and 1.6:1 (parasitoid:egg) proportions on D. saccharalis eggs were evaluated, the second proportion being carried out in clutch deposited on sugarcane leaves. Trichogramma galloi presented a type II functional response, common among the parasitoids of the Trichogrammatidae family. Although the rate of parasitism on sugarcane borer eggs ranged from 43.36 to 53.77%, there was no significant difference between the evaluated proportions, 0.4:1 and 1.6:1 (parasitoid/egg).

Deleterious Effects of Cymbopogon nardus (L.) Essential Oil on Life Cycle and Midgut of the Natural Predator Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae).

Cymbopogon nardus (citronella) essential oil (EO) has been widely used in the cosmetic and food industry due to its repellent and fumigant properties. The aim of this study was to evaluate its effects on the life cycle and midgut morphology of the natural predator Ceraeochrysa claveri. Larvae were fed on sugarcane borer eggs (Diatraea saccharalis) pretreated with citronella EO solutions (1-100 µg/mL in methanol, 5 s) or solvent and air-dried at room temperature for 30 min. Larval and pupal stage duration, the percentage of emergence of the insect, and malformed insects were recorded. One day after adults emerged from their cocoons, adult insects were used to obtain their midgut and analyzed using light microscopy. The chemical composition of C. nardus EO revealed that citronellal (25.3%), citronellol (17.9%), geraniol (11.6%), elemol (6.5%), δ-cadinone (3.6%), and germacrene D (3.4%) were the predominant compounds. Exposure to the EO produced a significant change in development duration for third instar and prepupa of the insect. The observed alterations in the lifecycle included prepupae with no cocoon formation, dead pupa inside the cocoon, and malformed adults. Several injuries in the midgut epithelium of exposed adults were registered, such as detachment of columnar cells leaving only swollen regenerative cells fixed on the basement membrane, and the formation of epithelial folds. In summary, these data suggest that C. nardus oil has adverse effects on the life cycle and midgut morphology of a beneficial predator.

<i>Euborellia annulipes</i> Mortality and Predation on <i>Diatraea saccharalis</i> Eggs after Application of Chemical and Biological Insecticides

Chemical and biological insecticides have been frequently used in sugarcane fields to control insects-pests, including the sugarcane borer, Diatraea saccharalis. Among the products used, those based on chlorantraniliprole and Metarhizium anisopliae entomopathogenic fungus, stand out. Euborellia annulipes is an insect of the order Dermaptera considered a potential predator of sugarcane borer eggs. This study aimed to evaluate the direct and indirect effects of the bioinsecticide based on M. anisopliae (Metarril®) and the chemical insecticide chlorantraniliprole (Altacor®) on the mortality of E. annulipes nymphs and adults, the predation and feeding preference of earwigs in eggs treated with the formulated products. Predator mortality was evaluated for seven days after treatment, while the effect on predation was analyzed by preference tests with and without choice, using prey eggs. The products tested were selective to the predator, causing ≤ 2% mortality and not affecting predation. The application of M. anisopliae on sugarcane borer eggs favored the food preference of fourth-instar nymphs, males, and females of the predator. Our results show that Metarril® and Altacor® can be used to control D. saccharalis when associated with the predator E. annulipes.

Effects of parental diapause status and release time on field reproductive biology of the introduced egg parasitoid, Oobius agrili (Hymenoptera: Encyrtidae) in the Mid-Atlantic: Implications for biocontrol of the emerald ash borer (Coleoptera: Buprestidae)

Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), a solitary egg parasitoid native to China, was introduced to the United States for biocontrol of the invasive emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in 2007. To help develop effective biocontrol-release strategies, we evaluated the effect of parental diapause and release time of the adult parasitoids on their longevity, realized fecundity, and progeny diapause rate under field conditions in the U.S. Mid-Atlantic region in 2016 and 2017. Results from two years of the study showed that both non-diapaused and diapaused O. agrili adults released in rearing containers exposed to field conditions in late spring to early summer (from May 26 to July 20th) successfully survived and reproduced on emerald ash borer eggs provided throughout the study period. The parental parasitoid diapause status and release time did not significantly affect the longevity and life-time fecundity of the released adult parasitoids except that both diapaused and non-diapaused parasitoids released on May 26th of 2017 produced significantly fewer progeny than those from later releases (June 14th and July 20th) of the same year. In both 2016 and 2017, non-diapaused parasitoids consistently produced a higher proportion of diapaused progeny than diapaused parasitoids, regardless of release times. These findings indicate that releases of O. agrili with different diapause status from late spring to early summer may cause variations in establishing overwintering parasitoid populations for biological control of emerald ash borer in the field.

Peranan Parasitoid Telur Penggerek Batang Padi Putih Scirpophaga innotata (Walker) Pada Berbagai Fase Pertumbuhan Tanaman Padi

White stem borer Scirpophaga innotata Walkers is known as a species that always causes loss of rice yields in Indonesia and the Asia region and Australia. White stem borer attacks all stages of rice plant growth starting in the nursery until harvest. Until now, synthetic chemical pesticides are still a mainstay of farmers in controlling these pests. Then it is necessary to promote biological pest management, the use of biological agents is pest management technology because a save, economical and effective. Biological control through multiplication and parasitoid release needs to be focused on parasitoid it has adapted to the local environment. This study aims to examine the role of egg parasitoid S. innotata through the type and level of egg parasitization at various phases of rice plant growth. This research was conducted by collecting as many white rice stem borer eggs as possible based on the growth phase of rice plants, i.e. age 11-25 days after planting (DAP), 26-40 DAP, 41-55 DAP, 56-70 DAP, and 71-85 DAP. Observations were made by counting hatching and non-hatching eggs, as well as the type and number of parasitoids that appeared. The results show that the egg parasitoid found was Trichogramma japonicum Ashmead, Tetrastichus schoenobii Ferriere, Telenomus rowani Gahan. The highest level of egg parasitization is at 71-85 DAP.

Overview of the use of biocontrol agents in the control of Indonesian sugarcane borers

Sugarcane-borers complex in Indonesia consists of a shoot borer (Scirpophaga excerptalis) and four stem borers (Chilo sacchariphagus, C. auricilius, Sesamia inferens and Tetramoera schistaceana). Control of these borers is carried out biologically through the release of egg parasitoid Trichogramma spp. There are four species of mass-produced egg parasitoids and are used in the borer control program, namely Trichogramma japonicum, T. chilonis, T. nanum, and T. minutum. During this time, to measure the level of effectiveness of egg parasitoid releases was through the level of stalk damage. The effectiveness of the release of egg parasitoid should be measured through the mortality rate of borer eggs or parasitization level by the parasitoid. The observations in sugar cane plantations with release and without release of the Trichogramma spp. showed that releases of T. japonicum and T. chilonis were not effective in causing borer egg mortality. The level of parasitization of the borers’ eggs in both plantations was not significantly different, and the parasitization of sugarcane borer eggs was observed mostly due to natural egg parasitoid species, such as Tetrastichus sp., Telenomus sp., and T. chilonis. Biological control of the sugarcane borer complex by mass release of egg parasitoid needs to be reviewed.

Study on varietal preferences and seasonal incidence of parasitoids of rice pests

The egg masses of yellow stem borer, larvae of leaf folder and rice horned caterpillar and eggs of ear head bug were collected randomly at fortnightly interval from four different varieties viz., CO 43, CO 50, CO 51 and CR 1009 from the rice field. The data was pooled and per cent parasitization was calculated to find out the varietal preference and seasonal variations of parasitoids. Among the four different varieties tested for the preference of parasitoids, per cent parasitization of stem borer egg mass was found to be more (26.59) in CO 50. The per cent parasitization of leaf folder larvae and rice horned caterpillar was found to be maximum in CO 51(40.29) and CO 43(33.21), respectively. In case of ear head bugs, the egg parasitization was maximum (27.70) in CO 50. The mean egg mass parasitization of stem borer was highest (71.88) in first fortnight of December. The larval parasitization of leaf folder and rice horned caterpillar were found to be maximum during the second fortnight of December (64.3) and the first fortnight of January (71.88), respectively. The parasitism rate of ear head bug eggs was maximum (62.95) during the second fortnight of December. Interestingly, phoresy exhibited by Sceliocerdo sp. an egg parasitoid of Neorthacris sp. was also recorded.

Host range expansion may provide enemy free space for the highly invasive emerald ash borer

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an aggressive invader from Asia that has killed millions of trees in North America, causing substantial ecosystem effects and economic losses. All North American ash, Fraxinus spp., are thought to be susceptible, but recently emerald ash borer has been documented developing in a novel host, white fringetree, Chionanthus virginicus. We evaluated larval performance in two common ash species and white fringetree by infesting bolts with emerald ash borer eggs. In addition we evaluated cambial nitrogen, carbon, carbon:nitrogen, stem density, and response to artificial wounding, to determine which host plant characteristics most influence larval development. We also conducted choice and no choice assays using the classical biological control agent, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), to assess its ability to locate larval emerald ash borer in the different host plants. We found significantly lower survival rates of emerald ash borer larvae in white fringetree compared to white ash, F. americana. Larval phloem consumption and larval growth were lower in fringetree than in either white or blue ash, F. quadrangulata. Carbon content and density were greater in fringetree than in either ash species. Response to wounding, measured by callus tissue formation, was greatest in white ash. In choice assays, T. planipennisi only parasitized emerald ash borer larvae in ash bolts, and in no-choice tests failed to parasitize larvae in fringetree. Our findings corroborate studies showing that fringetree is a suitable host for emerald ash borer larvae. Failure of T. planipennisi to parasitize larvae within fringetree has implications for the efficacy of this classical biological control agent in regulating emerald ash borer populations. Coupled with the use of white fringetree as a reservoir host, the enemy free space provided to emerald ash borer through use of this alternate host may have significant repercussions for emerald ash borer invasion dynamics.

Occurrence of Telenomus dignus (Gahan) on the Sugarcane Borers, Scirpophaga intacta Snellen and Chilo sacchariphagus Bojer in Guangxi Province, China

Sugarcane (Saccharum officinarum L.) is an important crash crop in Guangxi, China. The sugarcane borers (Scirpophaga intacta Snellen and Chilo sacchariphagus Bojer) cause serious damage to sugarcane crop in Guangxi Province. Consequently, increasing attention has been given into the investigation and development of biocontrol agents to control these pests. The parasitoid wasp Telenomus sp. has previously been reported as a natural enemy of sugarcane borers in Guangxi Province. Telenomus dignus is the species found parasitizing borer eggs in field in Fujian Province, but it has not been previously mentioned as natural enemy of these pests. T. dignus was collected on S. intacta egg masses and identified from Shangsi County of Guangxi Province during 2013. In these studies, the parasitic behavior of T. dignus on eggs of S. intacta and C. sacchariphagus was investigated under field conditions during 2013–2014. The results from the current study showed that the percentage of parasitized egg masses of S. intacta parasitized by T. dignus was 45.71 and 57.14% in 2013 and 2014, respectively, while in C. sacchariphagus egg masses, the percentage of parasitism by T. dignus was 45.28 and 51.09% in 2014, respectively. The sex ratio (female/male) of T. dignus adults on S. intacta was 1.45:1 in 2013 and 5.17:1 in 2014 and was 2.17:1 on C. sacchariphagus in 2014. T. dignus was the dominant egg parasitoid of these two species of sugarcane borers in isolated sugarcane regions in Guangxi Province. Further investigations on biology of T. dignus are required to develop this parasitoid as a more widespread biocontrol agent of sugarcane borers.

Assessment of Trichogramma japonicum and T. chilonis as Potential Biological Control Agents of Yellow Stem Borer in Rice.

Two species of Trichogramma wasps were assessed for their effectiveness against yellow stem borer Scirpophaga incertulas. A laboratory cage test with T. japonicum and T. chilonis showed that both species parasitized yellow stem borer egg masses at 60.0% ± 9.13% and 40.7% ± 7.11%, respectively, with egg parasitism rates of 15.8% ± 22.2% for T. japonicum and 2.8% ± 5.0% for T. chilonis. Once the host eggs were parasitized, emergence rates were high for both species (95.7% ± 0.12% for T. japonicum and 100% for T. chilonis). In paddy field trials, the two Trichogramma species were released at three densities (50,000/ha, 100,000/ha and 200,000/ha) in Southwestern China. Egg mass parasitism was 9% ± 7.7% for T. japonicum and 15% ± 14.1% for T. chilonis, and again only a relatively small fraction of eggs was successfully parasitized. No clear conclusion could be drawn on the most efficient release rate as no significant differences were found among the three release rates. A comparison of field-collected T. japonicum with T. japonicum and T. chilonis mass reared on Corcyra cephalonica showed significantly larger body size and ovipositor length in field-collected wasps, suggesting potentially higher effectiveness on yellow stem borer eggs after at least one generation on the target host. Factors contributing to the low field parasitism rates are discussed.

Natural parasitism of the second generation European corn borer eggs Ostrinia nubilalis (Hübner) (Lepidoptera, Pyralidae) by Trichogramma spp. in sweet corn fields in Vojvodina, Serbia - short communication

Natural parasitism of the European corn borer eggs (Hübner) by Trichogramma spp. (Hymenoptera, Trichogrammatidae) was assessed in sweet corn field in north-west Serbia, region Vojvodina at the localities of Ruski Krstur, from 2004 till 2007. The rate of egg parasitism in 2004 varied from 35.89% to 73.58%. The parasitism in 2005 was lower than in 2004. On four different sampling dates in 2005 parasitism varied from 28.48% to 57.05% and averaged 39.4%. In 2006 parasitism fluctuated between 9.31 and 62.9%, averaging 32.15%. In 2007 parasitism varied from 36.8% to 54.54% and averaged 43.48%. The egg parasitoid species was identified as Trichogramma evanescens (Westwood). The study showed that this natural enemy occurred constantly in sweet corn fields but its number greatly fluctuated from year to year.

Assessment of yield loss in rice caused by Scirpophaga incertulas (Walk.) at Gangetic New Alluvial Zones of West Bengal, India

A field experiment was conducted in both kharif and boro season for assessment of yield losses of Scirpophaga incertulas (Walk.) in locally adopted rice cultivar IET 4786 during 2012 to 2014. Four different levels of released egg masses viz. t1 = one egg mass/m2, t2 = two egg mass/m2, t3 = three egg mass release/ m2 and t4 = no egg mass/m2 area were randomized in four replication and data were recorded at vegetative and reproductive stage respectively. Maximum percent of dead hearts subsequent white ear heads were recorded in case of 3 numbers of yellow stem borer (YSB) egg masses/m2 followed by 2 numbers of YSB egg masses/m2 and one number of YSB egg mass/m2 during both kharif and boro season respectively. the regression equation for extent of yield reduction for dead heart (DH) was by 0.0887 units whereas for white ear (WE) was by 0.3269 units. Correlation model explains that the extent of yield loss corroborates the extent of infestation. the yield loss was calculated with respect to control which revealed that 3 numbers of YSB egg masses/m2 exhibited its supremacy 35.31% followed by 2 numbers of YSB egg masses/m2 (28.78%) and one numbers of YSB egg mass/m2 (25.45%). A separate regression equation was developed from boro season of 2013 and 2014 where per unit increase in DH and WE caused yield reduction by 0.078 and 0.2745 units respectively. results show that the overall damage percentages were constantly increased from vegetative to reproductive stage. Here per unit increase of subsequent dead heart and white ear caused yield reduction by 0.0887, 0.3269 and 0.078, 0.275 units in kharif and boro seasons respectively and clipping of Scirpophaga incertulas (Walk.) egg masses could save at least 7.142% and 13.040% damage in a crop period.

Establishment of classical biological control targeting emerald ash borer is facilitated by use of insecticides, with little effect on native arthropod communities

Emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), is rapidly invading North America and has inflicted extensive ash, Fraxinus spp., mortality in affected areas, altering composition and structure of wildland and urban forests. Insecticides can effectively protect ash on a small scale and classical biological control efforts have been implemented. In the U.S. emerald ash borer kills native ash so quickly, and populations are so mobile, that establishing an effective biological control program is challenging. Consequently, we assessed the compatibility of using reduced rates of the insecticide imidacloprid applied as a soil drench coupled with releases of three species of parasitic wasps. In this way we hope to slow the process of ash decline and prolong the window of opportunity to allow biological control agents to become established. We compared the efficacy and effects of i) full strength imidacloprid applications, ii) reduced rates of imidacloprid coupled with classical biological control, iii) classical biological control alone, and iv) untreated controls. We monitored emerald ash borer adult activity through trapping and destructive sampling for larvae, evaluated larval parasitization rates, and also assessed the native hymenopteran communities. Chemical treatments were not adequate to prevent ash canopy decline, but they also did not impede parasitization of emerald ash borer eggs or larvae. Two of the three classical biological control agents, Oobius agrili and Tetrastichus planipennisi, were recovered from trees treated with imidacloprid, demonstrating that they were successfully reproducing and indicating the compatibility of the two management strategies. Non-target hymenopterans appeared unaffected by the insecticide applications. Importantly we found no negative effects of the imidacloprid applications on native pollinators. Collectively these data suggest that judicious use of insecticides coupled with classical biological control may be an effective and potentially sustainable approach to managing invading populations of emerald ash borer.

Larval Survival and Growth of Emerald Ash Borer (Coleoptera: Buprestidae) on White Ash and White Fringetree Saplings Under Well-Watered and Water-Deficit Conditions.

Emerald ash borer (Agrilus planipennis Fairmaire) was recently found on a novel host in North America, white fringetree (Chionanthus virginicus L.) (Oleaceae). In this study, we artificially infested 4-yr-old, naïve white fringetree and white ash (Fraxinus americana L.) saplings under well-watered and water-deficit conditions with emerald ash borer eggs. We used physiological and phenotypical approaches to investigate both plant response to emerald ash borer and insect development at 21, 36, and 61 d postinfestation. Photosynthesis was reduced in both tree species by larval feeding, but not by water deficits. Emerald ash borer larvae established and survived successfully on white ash. Both establishment and survival were lower on white fringetree than on white ash. Larvae were larger, and had reached higher instars at all three time points on white ash than on white fringetrees. Larvae grew faster in white ash under water-deficit conditions; however, water-deficit conditions negatively impacted survival of larvae at 61 d postinfestation in white fringetrees, although head size did not differ among surviving larvae. White ash showed higher callus formation in well-watered trees, but no impact on larval survival was observed. In white fringetree, callus formation was not affected by water treatment, and was inversely related to larval survival. The higher rate of mortality and slow growth rate of larvae in white fringetree as compared to white ash suggest that populations of emerald ash borer may be sustained by white fringetree, but may grow more slowly than in white ash.

TINGKAT PARASITASI PARASITOID TELUR PBPK PADA PERTANAMAN PADI DENGAN BEBERAPA KETINGGIAN TEMPAT BERBEDA

Rice is the staple food of Indonesia's population. Various problems occur in an effort to increase production and productivity. One problem is the attack of yellow rice stem borer (PBPK) which may result in yield losses up to 90%. Utilization of parasitoid is an alternative to suppress the attack of Yellow Rice Stem Borer. The study was conducted in Tabanan, covering three locations with the altitudes of 50, 300, and 550 meters above sea leve, and at the Plant Pests and Diseases laboratory of the Faculty of Agriculture, University of Udayana. The study aimed to determine the effectiveness of parasitization of the best Yellow Rice Stem Borer as a natural control agent at different altitudes. The method used was survey by taking a sample group of Yellow Rice Stem Borer eggs with a purposive random sampling in the area of 2.5 hectares (one block in each location was an area of 0.5 hectares) at each location. Observations on parasitoid found in Yellow Rice Stem Borer eggs were done on parasitoid species diversity, equality, abundance, parasitation level, sex ratio, and the pattern of parasitoid invasion. The results showed three species of parasitoid eggs PBPK as biological control agents. Parasitation level of T. rowani and T. japonicum was the highest at the altitude of 50 meters above sea level, while T. schoenobii at the altitude of 300 and 500 meters above sea level.

Trichogramma parasitoids for control of Lepidopteran borers in Taiwan: species, life‐history traits and Wolbachia infections

AbstractTrichogramma, polyphagous endoparasitoids of lepidopteran eggs, are used against a variety of crop pests throughout the world including those of sugar cane and corn in south‐eastern Asia. Their ability to be easily and economically reared on factitious hosts and their wide host range have contributed to their widespread use in pest control. The overall aim of this study was to select strains for eventual release in crop areas for control of lepidopteran borer pests of sugar cane and corn. To this end, we identified common Trichogramma species emerging from corn borer egg masses throughout south‐western Taiwan, compared their life‐history characteristics, assessed their thermal limits and identified the Wolbachia infection status of collected Trichogramma parasitoids. Trichogramma ostriniae was the most commonly collected species on corn, with occasional detection of T. chilonis and an unidentified species designated as T. sp. y. Although the sex ratio varied widely between sites, Wolbachia infection was detected only at a single site in one species (T. ostriniae). Wolbachia‐infected T. ostriniae were tolerant to high temperature stress. Trichogramma chilonis had lowest fecundity of the three species tested, and a Wolbachia‐infected T. ostriniae strain had lower fecundity than an uninfected strain. Given the limited availability of distribution and historical data for Trichogramma species in Taiwan, the current study provides a baseline for future work and also highlights the importance of accurately identifying species when establishing colonies of natural enemies for biocontrol.

Growth of Larval Agrilus planipennis (Coleoptera: Buprestidae) and Fitness of Tetrastichus planipennisi (Hymenoptera: Eulophidae) in Blue Ash (Fraxinus quadrangulata) and Green Ash (F. pennsylvanica).

Emerald ash borer (Agrilus planipennis Fairmaire) is an invasive primary pest of North American ash (Fraxinus spp.) trees. Blue ash (F. quadrangulata) is less susceptible to emerald ash borer infestations in the forest than other species of North American ash. Whereas other studies have examined adult host preferences, we compared the capacity of emerald ash borer larvae reared from emerald ash borer eggs in the field and in the laboratory to survive and grow in blue ash and the more susceptible green ash (F. pennsylvanica). Emerald ash borer larval survivorship was the same on both ash species. Mortality due to wound periderm formation was only observed in living field grown trees, but was low (<4%) in both green and blue ash. No difference in larval mortality in the absence of natural enemies suggests that both green and blue ash can support the development of emerald ash borer. Larvae reared from eggs on blue ash were smaller than on green ash growing in the field and also in bolts that were infested under laboratory conditions. In a laboratory study, parasitism rates of confined Tetrastichus planipennisi were similar on emerald ash borer larvae reared in blue and green ash bolts, as were fitness measures of the parasitoid including brood size, sex ratio, and adult female size. Thus, we postulate that emerald ash borer larvae infesting blue ash could support populations of T. planipennisi and serve as a potential reservoir for this introduced natural enemy after most of the other native ash trees have been killed.

Impact of Multiple Insect-Pest Incidence on Yield in Basmati Rice

The experiments for determining the multiple insect-pest incidence on yield loss in basmati rice was conducted for two crop seasons. Five treatments were, viz. application of imidacloprid in vegetative stage; application of granular insecticide in vegetative stage; application of higher dose of Urea; augmentive releases of yellow stem borer egg mass at vegetative and booting stage; untreated control. During both the years, the correlation between grain yield and dead heart, leaf folder damage and planthopper population at 50 and 65 DAT and white ear at maturity was negative. The analysis of variance of regression analysis of yield Vs damage levels at different crop growth stages during both the years revealed a significant linear relationship. The yield loss was highly related to incidence of stem borer and leaf folder damage at 50 and 65 DAT during both the years. For integrated pest management, effective monitoring of stem borer and leaf folder from 50 to 65 DAT is required, which appeared as a critical crop growth stage. The farmers should remain cautious during this period to prevent yield loss.