Maximum Parasitism Research Articles

Botanicals Vs Insecticides :Relative safety of recommended botanicals / insecticides for the management of Fall armyworm against Telenomus remus

The present study aimed to assessthe safety of insecticides and botanicals forFAW management against Telenomus remus. Laboratory investigation on the effect of botanicals / insecticides on the parasitic potential of T. remus on FAW eggs revealed maximum parasitization and parasitoid emergence from chlorantraniliprole treated eggs (97.2 and 95.4 %) followed by azadirachtin, emamectin benzoate, flubendiamide and Spinetorum. Similarly, pot culture study revealed maximum parasitization (97.0%) and parasitoid emergence (90.1%) in egg masses treated with chlorantraniliprole indicating the relative safety of chlorantraniliprole to T. remus. Chlorantraniliprole and emamectin benzoate control Fall armyworm. The foregoing experimental results show that T. remus can be a good candidate for integrated FAW management.

Biocontrol of Invasive Conical Snails by the Parasitoid Fly Sarcophaga villeneuveana in South Australia 20 Years after Release.

Simple SummaryTwo invasive conical snail species are major pests of pastures and grain crops in Australia. In 2000, a parasitoid fly, Sarcophaga villeneuveana, was sourced from the snails’ native Mediterranean range and introduced on the Yorke Peninsula, South Australia, for biological control of the conical snail Cochlicella acuta. The fly successfully established in the region but assessments of the fly’s impact in different snail habitats were limited. Twenty years on, four field surveys were performed over two years to measure its geographic spread and parasitism rates on C. acuta and the small pointed snail, C. barbara. In total, >88,000 snails were collected using standardised sampling methods to investigate the parasitism of host snails in different habitats. The fly was found at 13 of 19 sampled sites up to 34 km from nursery release sites. Total parasitism rates of suitably sized snails (≥5 mm shell height) were ≈3% for both C. acuta and C. barbara. Rates were higher in C. acuta (5.4%) and C. barbara (15.2%) in exposed habitats above ground level. Parasitism rates up to 48% in C. acuta and 29% in C. barbara at sites near flowering vegetation suggested that the fly benefits from floral resources.Two conical snail species introduced to Australia from the Mediterranean region during the 20th century are major pests of pastures and grain crops. In 2000, a parasitoid fly, Sarcophaga villeneuveana, was introduced into South Australia for biocontrol of the conical snail, Cochlicella acuta. The fly successfully established in the region but assessments of its impact in different snail aestivation microhabitats were limited. Twenty years on, field surveys were conducted to assess the geographic distribution and parasitism rates of S. villeneuveana on conical snails in the Yorke Peninsula region. Nineteen sites were sampled on four occasions in January and April of both 2019 and 2020. In total, >85,600 C. acuta and >2400 C. barbara were collected from cryptic (ground or plant refuge) and exposed (open ground or elevated substrate) aestivation habitats and assessed for parasitism. The fly was detected at 13 of 19 sampled sites up to 34 km from nursery release sites. Total parasitism rates of suitably sized snails (≥5 mm shell height) were 2.9% for C. acuta and 3.4% for C. barbara. Maximum parasitism rates of 48% for C. acuta and 29% for C. barbara were found at sites adjacent to spring- and summer-flowering native vegetation. Across 13 sites, parasitism rates were higher for C. acuta (5.4%) and C. barbara (15.2%) in exposed habitats above ground level. However, only 34% of C. acuta and 14% of C. barbara were found in elevated habitats as most snails were found in cryptic refuges. There was a seasonal decline in abundance of C. acuta (66%) and C. barbara (45%) between January and April, suggesting natural mortality. Although the overall impact of the fly is limited, high parasitism rates in local environments with flowering resources indicates the potential to enhance biocontrol of both invasive conical snail species.

Efficacy of the parasitoid, Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) against Myzus persicae (Sulzer) (Hemiptera: Aphididae) infesting rapeseed-mustard

• The parasitoid, D. rapae could parasitize on all nymphal instars of M. persicae . • The parasitoid showed a type II functional response to M. persicae . • An inverse relationship between parasitoid density and search-efficiency was noted. • Performance of D. rapae was better while parasitizing younger instars of M. persicae. Efficacy of Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) was determined by studying its biological and behavioural attributes on the aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). Total developmental duration of the parasitoid was longer in younger instars compared to that in older instars of aphid. Host age negatively affected the oviposition period and fecundity of the ovipositing parasitoid. Survival of the immatures was higher in older than the younger instars of the aphid. Sex ratio for the parasitoid was female-biased. Longevity of female parasitoid was higher while parasitizing aphid nymphs of younger age groups (1–2 days old) compared to that of older age groups (4–5 days old). Parasitoid showed a higher preference towards second instar of M. persicae both in choice and no-choice tests. Results on mutual interference revealed that per capita searching efficiency decreased from 0.91 to 0.07 as parasitoid densities increased from 1 to 8. Logistic regression exhibited a type II functional response for D. rapae . The estimated values of search-efficiency (a) and handling time (T h ) were 0.038 h −1 and 1.59 h, respectively. The maximum parasitization rate was 15.08. This investigation suggests that D. rapae could be an effective candidate for augmentative biological control of M. persicae which infests several plant species of economic importance.

Parasitism potential of Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on pupae of the fruit fly species, Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), during variable exposure durations

BackgroundFruit flies are important insect pests of horticultural crops. Pesticides used to control them which cause environmental and health hazards; therefore, other alternative sustainable management measures are required.Main bodySuccessful implementation of an integrated pest management program, using biological control agents, needs synchronization of parasitoids with hosts selection and exposure time. The present study was conducted to assess the biological activity of the parasitoid species, Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae), against the melon fruit fly, Zeugodacus cucurbitae (Coquillett), and the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), at different exposure durations (24, 48, and 72 h). The experiments were conducted under standard laboratory conditions. Significant differences in the parasitism rate of D. giffardii were observed for both species at different exposure durations. The maximum parasitism rate of D. giffardii (52.60 ± 2.84%) and (42.73 ± 2.74%) was observed at 48-h exposure period for Z. cucurbitae and B. dorsalis, respectively. Also, a comparison between both species showed a difference in parasitism rate at 24 and 48 h and a positive correlation between percent parasitism and exposure duration. Adult emergence of D. giffardii showed a maximum emergence rate from pupae of Z. cucurbitae (63.55 ± 4.02%) and B. dorsalis (51.61 ± 2.33%) at 10 days interval, respectively. However, the daily emergence of the parasitoid was not correlated to exposure duration in both species. The results of the present study may serve in the mass rearing of D. giffardii.ConclusionThe biological activity of D. giffardii was maximum at 48 h of exposure for both fruit fly species, and this important information may improve the mass rearing technology of D. giffardii.

Bio-efficacy of egg parasitoid, Trichogramma chilonis (Ishii) against spotted stem borer, Chilo partellus (Swinhoe) in Kharif maize

Maize stem borer, Chilo partellus, is the most serious and ubiquitous pest of maize not only in India but also throughout the Asian countries where it is a constant threat. The larvae, after hatching, enter the plant whorl and feed inside the plant for rest of the life. Owing to its cryptic behavior, insecticides are not the right choice. Moreover, unwarranted use of pesticides has directly increased the cost of cultivation and accounted for many health as well as environmental hazards. Use of biological control agents is far better than harmful agro-chemicals in terms of health benefits and ecosystem stability, provided they are effective enough to suppress the pest population. Egg parasitoid, Trichogramma chilonis, has proven its worth against many lepidopteran borers and provided satisfactory control in many crops. With this view, an experiment was conducted to evaluate the potency of T. chilonis against spotted stem borer, Chilo partellus at laboratory and research area of CCS Haryana Agricultural University, Regional Research Station, Karnal during Kharif, 2017. In our study, maximum egg parasitization (62.40%) was recorded in treatment with two releases of T. chilonis parasitized eggs @ 1,25,000/ha at 7 and 14 days after germination (DAG) which was at par with two releases of T. chilonis parasitized eggs @ 1,00,000/ha at 7 and 14 DAG (60%) whereas treatment with one spray of Dimethoate 30 EC @ 660 ml/ha had minimal T. chilonis activity (3.5% parasitization). Lower leaf injury rating (LIR), plant infestation and dead hearts were recorded in treatments with two release of T. chilonis parasitized @ 1,25,000 and 1,00,000 eggs/ha at 7 and 14 DAG which were statistically comparable with Dimethoate 30 EC treated plots. Whereas treatments with single release of T. chilonis parasitized eggs did not provide satisfactory control. Treatment with two releases of T. chilonis parasitized eggs @ 1,00,000/ha at 7 and 14 DAG was the most economically remunerative with the highest incremental cost: benefit ratio (1:32.48) and benefit: cost ratio (1.41). Although, pesticide treated plots (Dimethoate 30 EC @ 660 ml/ha at 7 DAG) provided satisfactory monetary return but it is not environmentally compatible and ecologically viable for long run.

Performance of Trichogramma chilonis on different host

The laboratory experiment was conducted during 2017-2018 to study the different biological attributes of Trichogramma chilonis Ishii as influenced by host eggs of different ages. Significantly maximum percent egg parasitization was noticed on eggs of Helicoverpa armigera (Hubner) with 62.39 percent which was at par with the Corcyra cephalonica (Stainton) eggs (60.36 percent). This was followed by Earias vittella Fabricius 46.31 percent. Less parasitized eggs were recorded in Leucinodes orbonalis Guenee (10.35 percent). Age of host eggs significantly affected the parasitization by T. chilonis . The maximum parasitization (58.87 percent) was noticed in fresh eggs i.e. 24 hrs old followed by 48 hrs (44.91 percent) while 72 hrs old eggs were less preferred by T. chilonis and could parasitize only 30.56 percent. Development period for parasitoid ranged between 8.66 to 9.44 days on different host eggs. The highest adult parasitoid longevity (7.22 days) was observed from the parasitized eggs of H. armigera which was at par with C. cephalonic a (7.10 days), E. vittella (6.88 days) and L. orbonalis (6.88 days). However, the different lepidopteran eggs as well as age of host eggs did not show significant differences pertaining to percent adult parasitoid emergence. Fresh host eggs of 24 hrs could produce more female progeny of T. chilonis (54.30 percent) compared to 72 hrs old eggs (42.65 percent). The sex ratio (male: female) of emerging parasitoid progeny was observed highest on 24 hrs old eggs (1:1.55) followed by 48 hrs old eggs (1:1.23) while lowest sex ratio was observed on the eggs of 72 hrs old age (1:0.95). The maximum per day fecundity of T. chiloni s was noticed on the 24 hrs old eggs (6.75) followed by 48 hrs old eggs (4.80). The lowest fecundity (2.05) of T. chilon is was observed on the 72 hrs old eggs, whereas the highest male-female ratio and fecundity was noticed on eggs of E. vittella among different hosts.

First Report of Native Parasitoids of Fall Armyworm Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Mozambique.

Simple SummaryIn 2016, a highly destructive insect pest with origin in the Americas was detected in Africa. The pest is known to feed primarily on maize which is a staple food in the continent. Since then, farmers have been using chemical insecticides to control the pest. Chemical insecticides are expensive and harmful to the environment. In this article, the authors Albasini Caniço, António Mexia, and Luisa Santos discuss the possibility of application of an alternative method of control known to be environmentally friendly and economically sustainable in the long term. The method, known as “biological control”, can be easily implemented by farmers, and has the potential to reduce the population of the insect pest and production costs, and bring long term benefits to the environment.The alien invasive insect pest Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), commonly referred to as fall armyworm (FAW), is causing significant losses to maize production in Africa since its detection in 2016. As an emergency response, governments in several countries distributed and/or promoted massive use of synthetic insecticides among smallholder farmers to fight FAW. The inappropriate use of synthetic insecticides by non-trained and ill-equipped farmers raises environmental and health concerns. This study aimed to assess the occurrence of native parasitoids of FAW, their parasitism rates, and relative abundance in the central province of Manica, Mozambique. A field collection of FAW egg masses and larvae was conducted from May to August 2019 (dry season of the 2018/2019 cropping season) and in December 2019 and January 2020 (rainy season of 2019/2020 cropping season). A total of 101 egg masses and 1444 larvae of FAW were collected from infested fields. Five larval parasitoids were recorded, but no egg parasitism was observed. Coccygidium luteum Brullé (Hymenoptera: Braconidae) and Drino quadrizonula Thomson (Diptera: Tachinidae) were the primary parasitoids. Maximum parasitism of 23.68% and 8.86% and relative abundance of 100 and 96.3 were recorded for C. luteum and D. quadrizonula, respectively. Total parasitism by different parasitoid species was at 9.49%. Cultural practices favoring the action of these parasitoids should be advocated.

Biology and Prevalence in Northern Italy of Verrallia aucta (Diptera, Pipunculidae), a Parasitoid of Philaenus spumarius (Hemiptera, Aphrophoridae), the Main Vector of Xylella fastidiosa in Europe.

Simple SummaryThe meadow spittlebug, Philaenus spumarius is the major vector of Xylella fastidiosa in Europe. The spread of X. fastidiosa depends almost exclusively on insect transmission, and therefore, it is vital to keep vector populations low. To achieve this goal, natural enemies should be identified and their efficacy evaluated. The aim of this work was to assess the presence and abundance of a parasitoid fly, Verrallia aucta, in field-collected spittlebugs. At first, we developed a new species-specific molecular tool (PCR) to identify the parasitoid, then we estimated the parasitization rate in different sites of northern Italy using both PCR and the dissection of insect bodies. Finally, we established a small-scale rearing to describe the life cycle of the fly on its spittlebug host. Verrallia aucta is quite common in northern Italy but displayed low prevalence, reaching a maximum parasitization rate of 17.5% in vineyards of the Piemonte region. The fly has one generation per year, lays eggs in newly emerged adults of spittlebugs, and develops inside the host throughout the summer. The mature larva abandons the dead victim at the beginning of autumn and pupates in the soil where it overwinters.The meadow spittlebug, Philaenus spumarius (L.) (Hemiptera Aphrophoridae), the main vector of Xylella fastidiosa Wells et al. in Europe, has few known natural enemies. The endoparasitoid Verrallia aucta (Fallén) (Diptera, Pipunculidae) was first noticed a long time ago but very little is known about its biology and prevalence. In this study, the presence and prevalence of V. aucta were investigated in different regions of northern Italy, both in plain–foothill and montane zones. Parasitic larvae were identified by the dissection of spittlebug adults, P. spumarius and Neophilaenus campestris (Fallén), and by a new species-specific molecular tool targeting the ITS2 and COI genomic regions, developed in this work. A small-scale rearing was set up to gain information on the life cycle of V. aucta on its main host P. spumarius. During the four-year investigation (2016–2019) the pipunculid parasitoid displayed low prevalence, reaching a maximum parasitization rate of 17.5% (calculated over the adult spittlebug season) in vineyards of the Piemonte region. Over the whole period, no significant difference in the prevalence was found between male and female spittlebugs. Collected data and rearing observations suggest that V. aucta is monovoltine and synchronous with P. spumarius, laying eggs in newly emerged adults, developing as an endoparasitoid through two larval stages during the whole summer, and overwintering as a pupa in the soil.

RETRACTED ARTICLE: Residual effect of two chemical insecticides on functional response of Habrobracon hebetor say (Hymenoptera: Braconidae) to Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

Braconid wasps are among the most successful parasitoids of lepidopteran pests worldwide. The sublethal effects of two chemical insecticides, lufenuron (Match®) and thiacloprid + deltamethrin (Proteus®), were studied on functional response of Habrobracon hebetor Say to Ephestia kuehniella Zeller larvae. Seven host densities (2, 4, 8, 16, 32, 64 and 96) were used during a 24 h period under controlled conditions of 27 ± 1 °C, 70 ± 5% R.H. and 16:8 h (L:D). The resulting data were appropriately fit to Type II functional response models in all treatments, including: (1) control (a = 0.0967 h−1; and Th = 0.2128 h); (2) lufenuron (a = 0.0950 h−1 and Th = 0.2162 h) and (3) thiacloprid + deltamethrin (a = 0.0806 h−1 and Th = 0.3431 h). The maximum theoretical parasitism rate (T/Th) was 112.78 estimated for control wasps. There was no significant difference between the values of attack rates (a and a + Da) in all treatments, while the handling time was statistically affected in female wasps treated with thiacloprid + deltamethrin. These findings will be useful to the safe deployment of lufenuron in pest management programs.

Parasitism potential of Aenasius advena Compere (Hymenoptera: Encyrtidae) on Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae)

The relative suitability of different immature life stages of Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae) as a host for the development of the parasitoid, Aenasius advena Compere (Hymenoptera: Encyrtidae) was investigated. Maximum parasitism (42.50%) under laboratory conditions was observed in the pre reproductive stage of host. The results of this study revealed that host life stage in which parasitoid larva complete its final instar is significant for its development. Parasitism of third instar and pre reproductive F. virgata yielded more number of males and females respectively. Considering the efficiency of parasitism, third instar and pre reproductive stage of F. virgata is the most suitable stage for mass rearing A. advena in the laboratory. Biological control is the best management strategy to control F. virgata since it helps reducing pesticide usage. Biological information gathered in this study is important to the development biological control programme of F. virgata.

Parasitism potential of Diadegma argenteopilosa (Cameron) (Hymenoptera : Ichneumonidae), an internal larval parasitoid of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera)

Diadegma argenteopilosa (Cameron) (Ichneumonidae: Hymenoptera) is an internal larval parasitoid of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera), a notorious and polyphagus pest of pulses and vegetables in India. Attempt has been made to initiate their mass multiplication for successful biocontrol programme. Behavioral studies, food stuffs, host selection aspects plays a crucial role in mass multiplication of biocontrol agents. Therefore, present work was conducted to study the optimum host age, specificity and host density for maximum progeny production of the parasitoid under laboratory conditions and later their release in the field for the management of pest species. The parasitoid caused highest mortality in the pest larvae of second instars, 4 day old larvae were attacked most with high percent parasitism, 39.00%. Optimum density for maximum progeny production of D. argenteopilosa was 20, which generate maximum parasitism (43.00%). Host specificity by exposing the parasitoids towards different host species and analyse parasitoid preference by S. litura > Helicoverpa armigera (Hubner) > Mythimna separata Walker > Achaea janata (Linnaeus). Nutritional requirement of parasitoid was tested with different foodstuffs and found 50% honey best suited for maximum longevity 8.2 and 11.4 days for males and females respectively. The longevity ratio also female biased, 1: 1.39 (Male: Female). From the results it concludes that D. argenteopilosa fed with 50% honey solution, exposed to 3-5 day old caterpillars of S. litura at density of 20 gave maximum progeny production and effectively utilized in the biocontrol programme.

Evaluation of the Parasitism Capacity of Egg Parasitoid Telenomus dignus on Chilo sacchariphagus

Telenomus dignus is an important egg parasitoid of sugarcane stem borers in China. Parasitism characteristics of T. dignus were studied by the methods of its functional response and the laboratory population life table. Results showed that the parasitism capacity of T. dignus on Chilo sacchariphagus showed a functional response of Holling II model. The maximum parasitism capacity was 66.23 eggs per female at the first day. The searching efficiency was 1.0917. The processing time was 0.0151, and the correlation coefficient was 0.9041, significant. The population life table of T. dignus was established in laboratory. The average life span of females was 6.9 days, which ranged from 3 to 13 days. The number of parasitized eggs on the first day of emergence accounted for about 33% of total number of eggs laid in a lifetime, while it reached approximately 60% in the first three days. The net fecundity and the average number of parasitized eggs were 42.35 and 77.9 per female, respectively. As the dominant natural enemy, T. dignus proved to be a remarkable egg parasitoid of C. sacchariphagus, providing a basis for using T. dignus to control C. sacchariphagus in sugarcane areas.

Population dynamics of Aleyrodes proletella L. (Hemiptera: Aleyrodidae) and its parasitoids in Düzce Province of Turkey

Cabbage whitefly, Aleyrodes proletella L. (Hemiptera: Aleyrodidae), causes severe damage to Brassica vegetables. This study was conducted to evaluate the seasonal population dynamics of A. proletella and its parasitoids throughout the 2016 and 2017 growing seasons in Duzce Province in Turkey. To estimate whitefly density and parasitism rates, collard leaf samples infested with whitefly were collected from fields where no pesticides were applied. Collard leaves were cultured for emergence of the adult parasitoids, which were identified as Encarsia tricolor Forster (Hymenoptera: Aphelinidae) based on morphological and molecular characteristics. Seasonal mean densities of A. proletella ranged from 11.20 to 19.30 nymphs/leaf in 2016 and from 15.19 to 86.66 nymphs/leaf in 2017. The highest parasitism rates were 6.46% and 24.79% in 2016 and 2017, respectively. Whitefly nymphs peaked in July and August during both years. The first parasitized whitefly nymphs were observed in July, and maximum parasitism rates occurred in the second half of August during both years. These findings provide significant contributions for studies involving the conservation of parasitism of A. proletella.

Effect of coriander plant extract on the parasitization behaviour of Trichogramma chilonis Ishii (Trichogrammatidae: Hymenoptera)

In the present investigation the coriander plant volatiles for the tritrophic interactions on the egg parasitoid Trichogramma chilonis Ishii is evaluated. The GCMS profile study of the foliage extract of coriander in both hexane and dichloromethane showed presence of 2-Dodecenal-(E), (E)-Tetradec-2-enal, Octadecane, Nonacosane, Hexadecane, Pentadecane and Heneicosane, which are of biologically active fractions in insects. In laboratory study the maximum parasitization was recorded in hexane extract treated Corcyra card (31.04 eggs/card) compared to 28.16 eggs per card observed in untreated control. The data gathered on number of parasitized eggs hatched into adult indicated that in hexane extract treated Corcyra card had 91.19 per cent while parasitoid emergence was 29.30 eggs per card followed by 87.76 per cent in untreated control 24.90 eggs per card. The GCMS profile study of the foliage extract of coriander in both hexane and dichloromethane showed presence of 2-Dodecenal-(E), (E)-Tetradec-2-enal, Octadecane, Nonacosane, Hexadecane, Pentadecane and Heneicosane, which are of biologically active fractions in insects. The above findings reveal the possible role of such active chemicals in parasitoid compatibility of the intercrop.

Incidence of egg and larval parasitoids of Chilo partellus on Kharif maize

The incidence of egg and larval parasitoids of Chilo partellus was monitored in insecticide free maize fields at the Indian Agricultural Research Institute, New Delhi, for three Kharif seasons of 2013 to 2015. The hymenopteran parasitoid, Trichogramma sp. was recorded to be the only egg parasitoid in this area, while a good number of larvae were parasitized by braconid, Cotesia flavipes . The egg parasitism was recorded on the freshly laid eggs of stem borer obtained by artificially releasing the adults of C. partellus on maize cultivars, HQPM1 and PMH1, at 12 days after germination. There was no egg parasitism recorded during Kharif 2013 and 2014, whereas 5.6 percent egg-mass parasitism by Trichogramma sp. was recorded during Kharif , 2015. The larval parasitoids were monitored by artificially infesting the maize plants with neonates of laboratory reared C. partellus . The larvae were allowed to develop on maize plants under field conditions for 20 days. The plants showing stem borer damage were cut and brought to the laboratory. The larvae collected from infested maize plants were reared in the laboratory. The maggots of C. flavipes recovered from parasitized larvae ranged from 29-100, 41-50 and 20-80 percent during Kharif 2013, 2014 and 2015, respectively. The result of this study indicated that parasitism by Cotesia was influenced by age of plants damaged by C. partellus . The young maize plants seemed to be more attractive to the foraging of Cotesia and more stem borer larvae were parasitized on these plants as the maximum (58 percent) parasitism was observed at 40-day-old crop. The parasitoid was found to be active on maize from 40-60 days after germination and the incidence decreased thereafter. Insecticides should not be used during this period. The current studies also revealed that host densities had no significant effect on percentage parasitism by Cotesia .

Mating Attributes Relating to Parasitization and Productivity in Habrobracon hebetor (Hymenoptera: Braconidae) Rearing on Host Indian Meal Moth (Lepidoptera: Pyralidae).

The mating attributes in relating to parasitism and progeny production capacity of the parasitoid Habrobracon hebetor Say, using Plodia interpunctella (Hübner) as a host, were investigated in laboratory studies. The results indicated that 100% of the host larvae were parasitized by different individuals of H. hebetor females that were mated by the same male. Mating duration did not differ significantly among different successive matings with different females and had no effect on the rate of parasitism. In general, pairs that had their copulation early after emergence exhibited the maximum rate of parasitism as compared to delayed intervals. Moreover, the age of the H. hebetor females had no effect on the percentage of parasitism. The maximum parasitism percentage was recorded for the H. hebetor individuals that had been developed from the age group of the 6-d-old adults. The male: female ratios did not differ significantly among the female age groups. The percentage of parasitism clearly indicated a decrease with the increase of the male: female ratio. Overall, the results of the present work can be further utilized in mass rearing and release of H. hebetor in biological control programs in stored product protection.

Impact of organic and conventional practices on rice yellow stem borer Scirpophaga incertulas (Walker) and its egg parasitoids

Organic farming, cultivation without pesticides and fertilizers promotes plant and animal diversity including insects. The present study conducted at the research farm of the ICAR-Indian Agricultural Research Institute, New Delhi evaluates the impact of organic and conventional IPM practices against rice yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Crambidae: Lepidoptera). Infestation at different stages of the crop and the efficiency of its egg parasitoids were assessed. Results indicated that infestation was more in conventional (0.59%) than the organic practice (0.47%). Three egg parasitoids observed include: Telenomus dignus Gahan, Tetrastichus schoenobii Ferriere, and Trichogramma japonicum Ashmead in both the practices, and all these are new records for the Delhi/NCR region. Maximum parasitization was observed with T. dignus (6.59%) followed by T. japonicum (0.58%) and T. schoenobii (0.42%), and it was during October. Egg parasitization was more in the organic practice (3.27±3.08) compared to the conventional one (1.18±0.99). The results reveal that T. dignus is the most dominant among the parasitoids observed.

Influence of intercrops in Coconut on Encarsia guadeloupae Viggiani parasitization of Rugose Spiralling Whitefly Aleurodicus rugioperculatus Martin

Field survey was undertaken from August 2017 to February 2019 in major coconut growing districts of Tamil Nadu viz., Coimbatore, Tiruppur, Erode, Theni, Pudukottai and Kanyakumari. During the survey on the parastization and emergence of Encarsia guadeloupae on new invasive pest of coconut rugose spiralling whitefly Aleurodicus rugioperculatus. The observation on the incidence of whitefly in coconut garden raised as sole crop and also with intercrops viz., Banana, Pearl millet, Cacao and Nutmug. Among the host plants, coconut and banana were the most preferred host for rugose spiralling whitefly. Assessment of parasitization of Encarsia guadeloupae was carried out in the destructive samples of coconut leaves collected from coconut raised as sole crop and also from coconut raised with intercrops. The results of the observation showed that among all cropping patterns, maximum parasitization of 78.0% was observed in mono crop of banana followed by 70.8% parasitization and 66.3% emergence were observed in coconut + banana. While least parasitization and emergence were observed in coconut + cacao cropping pattern. Eventhough banana is an alternate host for rugose spiralling whitefly, when raised as intercrop with coconut the parasitization of Encarsia guadeloupae on rugose spiralling whitefly increased.

Efficacy of egg parasitoid in management of brinjal shoot and fruit borer, Leucinodes orbonalis Guen�e

The relative efficacy of Trichogramma chilonis (Ishii) was evaluated for management of the brinjal shoot and fruit borer in the field condition at the Horticulture Farm of Rajasthan College of Agriculture, MPUAT, Udaipur from July 2016 to February 2017. The result showed that when three dosages of egg parasitoid, T. chilonis applied with 6 and 8 times releases @ 50000, 100,000 and 150,000 parasitized eggs at 10 days interval starting from 15 days after transplanting, releases of 150,000 for 6 and 8 times was found to be most effective with mean shoot damage of 11.96 and 12.66 per cent, respectively, while, the least effective rate was when parasitoid was released @ 50000/ha (T2 and T1) with mean shoot damage of 17.78 and 18.12 per cent, respectively, against fruit borer damage. Six and eight times release of T. chilonis @ 150,000 was most effective with mean fruit damage of 11.67 and 9.80 per cent on number basis, and 11.59 and 9.90 per cent per cent fruit damage on weight basis. The results revealed that the maximum parasitism was recorded for treatments of 8 and 6 times @ 150,000 /ha (47.61 per cent to 47.05 per cent).

Effects of climatic changes on olive fly, Bactrocera oleae (Rossi) population dynamic with respect to the efficacy of its larval parasitoid in Egyptian olive trees

BackgroundThe potential effects of two parameters of climatic change conditions (temperature and relative humidity) on the population dynamics of the olive fly across the two ecological areas in Egypt were studied. The olive trees in El-Behera Governorate are more affected by the olive fly compared to the olive trees in the orchard of El-Fayoum Governorate. In this study, the character of climate change in influencing the dynamics of insect population and associated parasites was discussed at the regional level.ResultsThe results exhibited that the olive trees in the coast governorate were more susceptible to the olive fly than the inner governorate. The parasitism percentage was recorded 41.7 and 46.4% at the beginning of the seasons 2016 and 2017, respectively in El-Fayoum Governorate. In El-Behera Governorate, the maximum parasitism percentage was recorded 49.5% (2016 season), while the 2017 season, the parasitism percentage was recorded 50.4%. The majority of the ordinary parasite was Psyttalia concolor in the two regions.ConclusionThe study clarifies that there is a positive correlation between B. oleae abundance and the effects of temperature and its parasitoid, Psyttalia concolor. Further, there is no significance found between the olive fly and relative humidity and its parasitoid populations.