Zastrowi Sillemi Research Articles

Functional Response of Chrysoperla Zastrowi Sillemi (Esben-Peterson) on Lipaphis erysimi (Keltenbach)

Biological control of insect pests depends upon predating potential of natural enemies, which in turn relate to their functional response that is key to selection of a proper species for the biological control programs. The main aim of the study was to access the functional response of second instar grub of C. zastrowi sillemi (Neuroptera: Chrysopidae) on Raya (Brassica juncea) aphid Lipaphis erysimi (Keltenbach). Five different predator: prey densities of aphids (1:50, 1:100: 1:150, 1:200 and 1:250) were taken and results indicated the type-II functional curve response by logistic regression analysis of C. zastrowi sillemi on L. erysimi. Hollings Type II functional response signifies that the rate of prey consumption by a predator rises as prey density increases, but eventually remains constant in spite of increase in prey density. The aphids consumption, search rate (a`) and maximum predation rate (1/Th) was recorded less (7.36, 0.06 and 0.40) as compared (7.56, 0.068and 0.467) when grubs fed on artificial diet. However, time taken to handle a prey by second instar grub was more (2.55) on natural diet but less (2.17) on artificial diet.

Impact of Thermal Stress on Biological Parameters of Chrysoperla zastrowi sillemi (Esben Petersen) under Laboratory Conditions

Aphid lions (Chrysoperla zastrowi sillemi, Esben-Petersen) are important predators in integrated pest management for field crops and vegetables (Neuroptera: Chrysopidae). It is found in almost every environment on Earth, except temperate ones. One of the most significant environmental variables influencing an insect species' growth rate is temperature. Five consistent temperatures were observed: 20±1°C, 25±1°C, 30±1°C, 35±1°C, and 40±1°C. The impact of temperature on biological parameters and developmental phases of Aphid lions feeding on rice moth eggs was noted. The development time of C. zastrowi sillemi was found to be 47.26 days at 20°C and 22.18 days at 40°C. The lifespan of adult males and females was more than twice as long at the lower temperature range as it was at the higher one. The temperature of 25°C produced the greatest duration of oviposition (55.12 days), the highest percentage of pupils (91.43%) and adults’ emergence (90.25%), the maximum fecundity (903.33 eggs/female), and the maximum degree of hatchability (90.84%) of eggs, suggesting that this temperature regime was more suited for the C. zastrowi sillemi that originated in Delhi. The results demonstrate significant variations in the developmental cycle of the immature stages at five distinct temperatures, with a negative relation between temperature increase and developmental duration.

Population dynamics of insect pests and their natural enemies in pearl millet ecosystem

Field experiment was carried out at the Regional Agricultural Research Station, Vijayapura, to study population dynamics of insect pests and their natural enemies in pearl millet ecosystem. The present study revealed that, dead heart per cent (14.45%) due to shoot fly, Atherigona approximata (Malloch) was peak during 35th Standard Meteorological Week (SMW), per cent damage due to stem borer, Chilo partellus (Swinhoe) was at peak during the 37th SMW (4.55%) and highest blister beetle, Lytta sp. population was observed during 38th SMW (12 beetles/ 5 Ear heads). While, the maximum population of aphid Rhopalosiphum maidis (Fitch) and its predators, such as coccinellids Cheilomenes sexmaculata (Fabricius), Harmonia octomaculata (Fabricius) and spiders were recorded during the 34th SMW and the green lacewing Chrysoperla zastrowi sillemi (Ebson-petersen) population at 35th SMW. The correlation studies indicated that, dead heart per cent due to shoot fly revealed a significant positive correlation with maximum temperature (r= 0.588*) and stem borer infestation revealed a significant positive correlation with maximum relative humidity (r= 603*) and sunshine hours (r= 585*). None of the weather parameters showed a significant correlation with the incidence of blister beetle and aphid populations.

Functional response of green lacewing, Chrysoperla zastrowi silemmi (Esben-Petersen) to its prey, cabbage aphid, Brevicoryne brassicae L.

Functional response influences the prey-predator interactions and hence is crucial for assessing the predatory potential of a given species. Laboratory studies were conducted at Dr. Y. S. Parmar University of Horticulture and Forestry, Solan, Himachal Pradesh, India during 2019-20 to assess the functional response of a generalist predator, Chrysoperla zastrowi sillemi (Esben-Petersen) (Neuroptera: Chrysopidae) against the cabbage aphid, Brevicoryne brassicae L. The feeding efficiency of larvae of C. zastrowi sillemi against varying densities of aphid i.e. 5, 10, 15, 20 and 30 was evaluated. The number of aphids consumed differed with prey densities and it was in direct proportion to the host density. All the three instars of C. zastrowi sillemi followed type II functional response. The attack rate (a) of the third instar larvae was maximum compared to first and second instars indicating the higher efficiency of later instar in prey consumption. Other parameters viz., the effectiveness of predator (a/th) and maximum predation rate (K) also followed similar trend while the prey handling time (Th) by the first instar took longer period (0.50 h) compared to second and third instars (0.46 h and 0.27 h, respectively). Searching efficiency was highest in the third instar which can be attributed to the higher mobility of fully grown larvae.

Functional response of green lacewing, <i>Chrysoperla zastrowi silemmi</i> (Esben-Petersen) to its prey, cabbage aphid, <i>Brevicoryne brassicae</i> L.

Functional response influences the prey-predator interactions and hence is crucial for assessing the predatory potential of a given species. Laboratory studies were conducted at Dr. Y. S. Parmar University of Horticulture and Forestry, Solan, Himachal Pradesh, India during 2019-20 to assess the functional response of a generalist predator, Chrysoperla zastrowi sillemi (Esben-Petersen) (Neuroptera: Chrysopidae) against the cabbage aphid, Brevicoryne brassicae L. The feeding efficiency of larvae of C. zastrowi sillemi against varying densities of aphid i.e. 5, 10, 15, 20 and 30 was evaluated. The number of aphids consumed differed with prey densities and it was in direct proportion to the host density. All the three instars of C. zastrowi sillemi followed type II functional response. The attack rate (a) of the third instar larvae was maximum compared to first and second instars indicating the higher efficiency of later instar in prey consumption. Other parameters viz., the effectiveness of predator (a/th) and maximum predation rate (K) also followed similar trend while the prey handling time (Th) by the first instar took longer period (0.50 h) compared to second and third instars (0.46 h and 0.27 h, respectively). Searching efficiency was highest in the third instar which can be attributed to the higher mobility of fully grown larvae.

Biological control potentials of Chrysoperla zastrowi sillemi (Neuroptera: Chrysopidae) against Bemisia tabaci (Hemiptera: Aleyrodidae) on polyhouse grown parthenocarpic cucumber in North-Western India

The silver leaf whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), stands out as a highly destructive insect in temperate, tropical, and subtropical regions, inflicting extensive damage to agricultural crops worldwide. Its impact resonates in India, where it has emerged as a formidable pest. Moreover, the excessive use of chemically-derived pesticides has led to the emergence of insect-resistant strains, resulting in environmental pollution and endangering human health. The use of natural enemies is a sustainable and environmentally safe alternative management tactic. The predation potential of green lacewing, Chrysoperla zastrowi sillemi Esben-Peterson (Neuroptera: Chrysopidae) on eggs, nymphs and adults of B. tabaci infesting parthenocarpic cucumber grown under polyhouse has been examined here. On cucumber plants, three releases of 2nd instar C. zastrowi sillemi larvae (at one, two and three larvae/plant) were made at 7 days intervals. The release of three larvae/plant resulted in significantly higher predation rate on whitefly population (58.6% on egg, 61.0% on nymph and 32.3% on adult stage of the whitefly) than two or one green lacewing larvae/plant (56.3% on egg, 58.3% on nymph and 30.4% on adult stage of the whitefly & 49.9% on egg, 51.0% on nymph and 24.6% on adult stage of the whitefly, respectively). Significantly higher yields of cucumber were recorded from plots with the release rate of three larvae per plant (2047.9 g/plant). Augmentative biological control of B. tabaci under polyhouse conditions with three weekly releases of 2nd instar C. zastrowi sillemi larvae at three larvae per plant can effectively manage whitefly infestation on parthenocarpic cucumber under polyhouse condition.

Sublethal Effects of Chitosan-O-Arginine, a Chitosan Based Insecticidal Compound against Green Lacewing Chrysoperla zastrowi sillemi (Esben-Petersen)

The widespread application of synthetic chemicals leads to the unintended negative impact to non-target organisms both directly or indirectly, as these chemicals can infiltrate new environments, disrupting established ecological niches. Laboratory experiments explored the effects of sublethal doses of Cs-O-Arg to the third instar grubs of Chrysoperla zastrowi sillemi when fed with treated and untreated larvae of diamondback moth (DBM). The results showed that when the untreated third instar C. zastrowi sillemi grub was fed with treated P. xylostella larvae at LC25, LC35 and LC45 concentrations, there was 6.67 per cent mortality of C zastrowi sillemi grub at all the concentrations, after 48 and 72 hours of exposure. but, when the treated C. zastrowi sillemi grubs (LC35 and LC45) were fed with untreated P. xylostella, there was only 3.33 and 10.00 per cent mortality of C. zastrowi sillemi grubs, respectively. Whereas, Cs-O-Arg caused 33.33 per cent mortality when LC45 treated grubs were provided with LC45 treated DBM larvae as feed, whereas the treatment with LC25 concentrations of Cs-O-Arg resulted in the highest pupation percentage (76.67%) and adult emergence rate (73.33%) in C. zastrowi sillemi grubs when fed with DBM larvae treated with the same concentration. Chitosan derivative insecticide causes a mild adverse impact on the survival of the economically significant insect predator C. zastrowi sillemi, which hold valuable implications for guiding decisions regarding the compatible utilization of insecticides alongside C. zastrowi sillemi or other natural predators within integrated pest management strategies.

Efficacy of Some IPM Strategies against Cotton Mealybug <i>Phenacoccus solenopsis</i> Tinsley

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), has become a widespread serious pest and causing economic losses. In an attempt to control this different organic amendments, seed treatment practices, plant products and insecticides were evaluated. The highest kapas yield of 7.8 q/ ha was recorded in flonicamid treated plots followed by 7.7 q/ ha in thiodicarb treated plots as against 2.8 q/ ha in control. Cost-benefit ratio was also higher in these treatments recording 1.83 and 1.81 CBR, respectively. Though the insecticides were found effective, organic amendments + foliar spraying of plant products treatments was safer to coccinellids recording 13.5 and 14.2/ 10 plants. The same trend was also observed with regard to Chrysoperla zastrowi sillemi and spiders coccinellids varied from 2.3 to 5.3, C. zastrowi sillemi from 2.1 to 3.2 no’s/ 10 plants in various insecticides sprayed fields as against 8.35 in control. Similarly, the population of spiders varied from 0.3 to 0.5 no’s/ 10 plants as against 2.47 in control.

Effect of Biopesticides on the Larval Mortality of <I>Chrysoperla Zastrowi Sillemi</I> (Esben-Peterson)

The efficacy of biopesticides; Bacillus thuringiensis, Lecanicillium lecani, Beauveria bassiana, Azadirachtin and fipronil (chemical check) on the larval mortality of Chrysoperla zastrowi sillemi was carried out during the year 2020-21 by two different methods viz. residue deposit and diet contamination, under laboratory conditions Result showed that in residue deposit method, the lowest larval mortality after 7 days was observed in Bacillus thuringiensis (9.33%) followed by Metarhizium anisopliae, Lecanicillium lecani and Beauveria bassiana (23.0, 24.0 and 26.67%, respectively). In diet contamination method, the lowest larval mortality (10.00%) was observed in Lecanicillium lecani followed by Metarhizium anisopliae, Beauveria bassiana and Bacillus thuringiensis (11.33% , 13.67% and 28.33%, respectively). The highest larval mortality in both the methods were observed in the check chemical fipronil (82.67% in residue deposit and 89.33% in diet contamination) followed by Azadirachtin (40.33% in residue and 58.00% in diet contamination). Keeping in view, the results demonstrated from the investigation the microbial pesticides was found to be compatible with Chrysoperla zastrowi sillemi and can safely be included in the integrated pest management programme against the pests.

Biology and predatory potential of chrysopids on invasive coconut rugose spiralling whitefly <em>Aleurodicus rugioperculatus</em> Martin

The relatively new invasive rugose spiralling whitefly (RSW) Aleurodicus rugioperculatus (Hemiptera: Aleyrodidae) has become a serious threat to oil palm, particularly coconut plantation, in southern India. Here, we report biology and foraging potential of predatory neuropteran Green lace wings Chrysoperla zastrowi sillemi (Esben-Petersen) and Mallada boninensis (Okamoto) (Chrysopidae) on against RSW. Results revealed that A. rugioperculatus served as a suitable host for the both chrysopid predators. C. z. sillemi completed its life cycle in 19.91±1.90 days with a larval (grub) period of 9.44±3.91 days and adult longevity was 24.10±1.87 days. The developmental period of M. boninensis was 22.3±2.93 days, with a larval period of 11.85±1.71 days, while the adult longevity was 19.25±1.52 day. In the laboratory experiment, all the larval stages of the predators were observed to feed on A. rugioperculatus. It was observed that the 3rd instar grub of C. zastrowi sillemi with the developmental period of 3.24±1.73 days consumed a maximum of 313.2 whiteflies (all the life stages) followed by second and 1st instar grub stages of the predator, which consumed mean number of 200.2 and 140.2 eggs and nymphs of A. rugioperculatus, respectively during their developmental period of 3.58±1.84 and 2.62±1.34 days, respectively. In the case of M. boninensis, a single grub could consume a total of 929.8 whiteflies (both eggs and nymphal stages) during its total larval period of 9.44±3.91 days.

Comparative Transcriptome Analysis to Reveal Differentially Expressed Cytochrome P450 in Response to Imidacloprid in the Aphid Lion, Chrysoperla zastrowi sillemi (Esben-Petersen).

Simple SummaryChrysoperla zastrowi sillemi (CZS) is a generalist predator of arthropod pests in different crops and is distributed in wide geographical regions. Being a natural predator, CZS shares an ecological niche with the pests and is exposed to several groups of pesticides including imidacloprid. Due to continuous exposure, it has developed resistance to several insecticides. Transcriptomes of imidacloprid-resistant and susceptible strains have been generated and compared for expression differences. From the transcriptome, sequences belonging to the CYP gene family have been mined for their nomenclature and classification into the four CYP clans. Putative functions of the CYP families in CZS have been identified by phylogenetic analysis including CYP sequences from Drosophila and Tribolium. Further, differential expressions of CYP genes have been validated using qRT-PCR. We found nine CYP genes to be downregulated and one to be upregulated after imidacloprid treatment. The information from current study can be exploited for the effective implementation of IPM as it aims at sustainable and eco-friendly crop yield improvement.The aphid lion, Chrysoperla zastrowi sillemi (Neuroptera: Chrysopidae) is a highly effective beneficial predator of many agricultural pests and has developed resistance to several insecticides. Understanding the molecular mechanism of insecticide resistance in the predators is crucial for its effective application in IPM programs. Therefore, transcriptomes of imidacloprid-resistant and susceptible strains have been assessed using RNA-seq. Cytochrome P450 is one of the important gene families involved in xenobiotic metabolism. Hence, our study focused on the CYP gene family where mining, nomenclature, and phylogenetic analysis revealed a total of 95 unique CYP genes with considerable expansion in CYP3 and CYP4 clans. Further, differential gene expression (DGE) analysis revealed ten CYP genes from CYP3 and CYP4 clans to be differentially expressed, out of which nine genes (CYP4419A1, CYP4XK1, CYP4416A10, CYP4416A-fragment8, CYP6YL1, CYP6YH6, CYP9GK-fragment16, CYP9GN2, CYP9GK6) were downregulated and one (CYP9GK3) was upregulated in the resistant strain as compared to the susceptible strain. Expression validation by quantitative real-time PCR (qRT-PCR) is consistent with the DGE results. The expansion and differential expression of CYP genes may be an indicator of the capacity of the predator to detoxify a particular group of insecticides.

Influence of Larval Diet on Pupal Period and Size of Cocoon of Chrysoperla zastrowi sillemi (Esben-Peterson)

A study was conducted in the Biocontrol Laboratory, Department of Entomology, College of Agriculture, OUAT, Bhubaneswar, Odisha during 2020-21 to record the influence of larval diets on pupal period and size of cocoon of Chrysoperla zastrowi sillemi (Esben-Peterson). Six larval diets i.e. T1 (Purple aphid, Aphis craccivora Koch.), T2 (Green aphid, Myzus persicae (Sulzer)), T3 (Mustard aphid, Lipaphis erysimi (Kalt.)), T4 (Papaya mealy bug, Paracoccus marginatus Williams and Granara de Willink), T5 (Pink mealy bug, Maconellicoccus hirsutus (Green)) and T6 (Corcyra cephalonica Stainton 1st instar larva) were tested along with one control (T7= Corcyra cephalonica egg). T1 was detected as the best larval diet which produced maximum pupal period of 8.90 days with 16.80% increased over control. Maximum cocoon diameter was also recorded in T1 i.e. 3.28 mm with 11.95% increased over control. T1 was closely followed by T3 with respect to pupal period (8.74 days with 14.70% increase over control) and diameter of cocoon (3.20 mm with 9.22% increase over control) of C. zastrowi sillemi.

Diversity of Natural Enemies Associated with Lac Insect <i>Kerria lacca</i> (Kerr) in Punjab

A survey was conducted to record the diversity of lac insect Kerria lacca (Kerr) associated natural enemies (predators/ parasitoids) during 2019-2020. In katki crop, the abundance of natural enemies ranged from 1.08 to 44.09%. There were three parasitoids viz, Parechthrodryinus clavicornis (Cameron) (1.08%), Aprostocteus purpureus (Cameron) (26.88%), Tachardiaephagus tachardiae somervilli (2.15%); and two predators; Chrysoperla zastrowi sillemi (5.38%), Eublemma amabilis (44.09%) and only one hyperparasitoid viz; Bracon greeni (Ashm.) (20.43%). Shannon-Weiner diversity index, evenness index and dominance index for natural enemies was found to be 0.67, 0.80 and 0.20. In baisakhi crop, the abundance ranged from 6.56 to 45.90% with maximum abundance of predator E. amabilis (45.90%) and the least of parasitoid T. tachardiae How. (6.56%); and the Shannon-Weiner diversity index, evenness index and dominance index was 0.65, 0.77 and 0.23, respectively.

Morphometry of different life stages of Chrysoperla zastrowi sillemi (Esben-Peterson) influenced by adult diets

A study was conducted in the Biocontrol Laboratory, Department of Entomology, College of Agriculture, OUAT, Bhubaneswar, Odisha during 2020-21 to record the influence of adult diets on morphometry of different developmental stages of Chrysoperla zastrowi sillemi (Esben-Peterson). Six adult diets, i.e. T1 (Water: Honey: Protinex :: 40: 40: 20), T2 (Water: Honey: Castor pollen :: 40: 40: 20), T3 (Water: Honey: Protinex: Castor pollen :: 40: 40: 10: 10), T4 (Water: Molasses: Protinex :: 40:40:20), T5 (Water: Molasses: Castor pollen :: 40: 40: 20) and T6 (Water: Molasses: Protinex: Castor pollen :: 40: 40: 10: 10) were evaluated along with control (T7=Water: Honey :: 50: 50). T1 was detected as the best diet which produced highest length and foot stalk length of egg, i.e. 0.96 mm and 4.53 mm with 10.34% and 12.69% increase over control. Maximum larval length was also recorded in T1 in all three instars, i.e. 2.38 mm, 3.48 mm and 4.87 mm, respectively. The cocoon diameter was recorded highest in T1, i.e. 2.57 mm. Length of adult male and female were recorded highest in T1, i.e. 10.73 mm and 15.52 mm with 12.00% and 14.79% increase over control. T1 was closely followed by T3 with respect to all morphometric measurements of developmental stages of C. zastrowi sillemi.

Efficacy of the green lace wing, Chrysoperla zastrowi sillemi (Esben-Peterson) (Neuroptera: Chrysopidae), against sucking pests of tomato: an appraisal under protected conditions

Pest infestations in net-houses are not sometimes different from that under open-field conditions, necessitating usage of pesticides. To examine the hypothesis that bioagents may have more potential under restricted plant growing conditions, the predatory potential of green lace wing, Chrysoperla zastrowi sillemi Esben-Peterson (Neuroptera: Chrysopidae) was evaluated against the sucking pests of tomato under screen-house conditions. The rates of release were fixed as 4, 5, and 6 s instar grubs plant−1 and a total of 3 releases were made at 7 days interval, with first release at appearance of the aphid, Myzus persicae (Sulzer) and whitefly, Bemisia tabaci (Gennadius). The pooled data for the years 2018 and 2019 revealed that, the release rates 4, 5, and 6 grubs plant−1 were not statistically different in reducing the population of these pests. The factorial analysis based on the release rate and time of these releases suggested that single release of C. zastrowi sillemi at 4 grubs plant−1 was effective against sucking pests in tomato grown under screen-house conditions.

Influence of colour on oviposition behaviour in green lacewing Chrysoperla zastrowi sillemi (Esben - Petersen) (Neuroptera: Chrysopidae)

The Green lacewing, Chrysoperla zastrowi silleni (Esben-Peterson), also known as “aphidlion” is a beneficial insect predator of various insect pests. The laboratory experiment was conducted during 2018-19 to evaluate the substrate colour preference for egg laying by C. zastrowi sillemi. Egg receiving sheets were pasted with white, black, green, indigo blue, yellow, brown, violet, sky blue, pink, red and orange colour papers. Among all colours C. z. sillemi females preferred orange colour as a substrate for egg laying with maximum number of eggs (43.13/female/day) followed by red colour substrate (25.50 eggs/female/day). White and black were least preferred.

Biology of green lacewing, Chrysoperla zastrowi sillemi (Esben-Petersen) on cabbage aphid, Brevicoryne brassicae L.

Laboratory experiments were conducted at Department of Entomology, Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India during 2019-20 to study the biology of green lacewing, Chrysoperla zastrowi sillemi (Esben-Petersen) on cabbage aphid, Brevicoryne brassicae L. The aphid culture was maintained on cabbage seedlings and the predator, C. zastrowi sillemi was reared on aphids. Duration of different developmental stages of the predator as well as adult longevity and sex ratio were recorded. The mean egg, larval and pupal periods were 4.82 ± 0.24, 11.2 ± 0.60 and 7.03± 0.29 days, respectively. The total developmental period was 21.4 ± 0.51 days. Larva of C. zastrowi sillemi had undergone three instars before pupation. The first instar had the shortest duration (3.80 ± 0.20 days) while the third instar lasted for longest period (4.25 ± 0.15 days). The pre oviposition, oviposition and total longevity of female adult were 6.60 ± 0.40, 25.40 ± 0.51 and 40.8 ± 1.28 days, respectively while longevity of male adult of C. zastrowi sillemi was 29.40 ± 1.86 days. The studies proved that predator, C. zastrowi sillemi could complete the life cycle on the cabbage aphid in about 20-23 days and can serve as a potential biocontrol agent to manage this pest.

Feeding potential of green lacewing, Chrysoperla zastrowi sillemi (Esben - Petersen) on two tailed mealy bug Ferrisia virgata (Homoptera: Pseudococcidae) and its bio-safety to insecticides

Green Lacewing, Chrysoperla zastrowi sillemi (Esben - Petersen) (Neuroptera: Chrysopidae) is one of the most important natural enemy and has a great role in reducing population of phytophagus insects in field crops and vegetables. Laboratory study was conducted during 2019–20 to record foraging potential of different larval stages of C. z. sillemi against two tailed mealybug Ferrisia virgata nymphs. Predator was found feeding on all the nymphal instars of F. virgata. Feeding potential of C. z. sillemi on the nymphs F. virgata revealed that maximum number of F. virgata nymphs (37.30) was consumed by third instar grub during its developmental period of 3.30 days. A total of 66.87 nymphs were consumed by C. z. sillemi during its total larval period of 9.16 days. The insecticide-tolerance and hatchability of eggs of C. z. sillemi was tested against six different insecticides viz, imidacloprid 17.8 SL (0.00712%), thiamethoxam 25% WG (0.005%), chlorantraniliprole 18.5 SC (0.0037%), fipronil 5% SC (0.01%), spinosad 45% SC (0.0125%) and azadiractin 1% EC (0.02%) having varied formulation used in guava ecosystem to control the pests. Interestingly, the hatchability of the eggs varied from 78.5% recorded in untreated check to 41.0% in imidacloprid 17.8 SL (0.00712%). Treatments were evaluated for their toxicity to C. z. sillemi third instar grubs. After 24 hrs of treatment, maximum grub mortality of 80.0% was encountered in thiamethoxam 25 WG (0.005%) treatment.

Impact of Bt cotton expressing single (Cry1Ac) and dual toxins (Cry1Ac and Cry2Ab) on the fitness of the predator Chrysoperla zastrowi sillemi (Esben-Petersen): prey-mediated tri-trophic analysis

Transgenic Bt cotton with genes from soil inhabiting spore forming bacterium Bacillus thuringiensis Berliner produces δ-endotoxin for the control of lepidopteran insects. The prey-mediated effects of Cry protein on the third trophic level is the most realistic exposure pathway that needs to be addressed as an important component of environment risk assessment. The green lacewing, Chrysoperla zastrowi sillemi (Esben-Petersen) (Neuroptera: Chrysopidae) is the most important generalist predator in the cotton ecosystem in India. The tri-trophic interactions involving Bt cotton expressing single (Cry1Ac) and dual toxins (Cry1Ac and Cry2Ab) fed herbivores, i.e. mealybug, Phenacoccus solenopsis Tinsley, whitefly Bemisia tabaci (Gennadius) and leafhopper, Amrasca biguttula biguttulla (Ishida) on the fitness of C. zastrowi sillemi, were studied. The development, survival and body weight of C. zastrowi sillemi had no deleterious effect as there were insignificant differences in any of the studied fitness parameters regardless of having consumed prey fed on Bollgard, Bollgard II and non-Bt cotton plants. The feeding potential of C. zastrowi sillemi on mealybug was also not different on Bt or non-Bt cotton plants. ELISA studies confirmed the presence of Cry proteins in Bt cotton leaves; however, no Cry1Ac or Cry2Ab protein was detected in prey herbivores (P. solenopsis, B. tabaci and A. biguttula biguttula) or in the predator C. zastrowi sillemi. It could be concluded that transgenic cotton that expresses single (Cry1Ac) or dual (Cry1Ac and Cry2Ab) toxins had no apparent effect on the fitness of the predator through its preys P. solenopsis, B. tabaci and A. biguttula biguttulla.

Natural enemies of whitefly, Bemisia tabaci (Gennadius) on cotton in Punjab, India

The whitefly, Bemisia tabaci (Gennadius) is a polyphagous pest, widely distributed in diverse agroecosystems across the globe. Several bioagents including predators and parasitoids from diverse groups have been recorded against whitefly worldwide. A field survey was conducted during 2016 and 2017 in different cotton growing districts of Punjab to record the natural enemies associated with whitefly. Sixteen species of natural enemies were recorded, including 7 species of insect predators; 2 species of parasitoids and 7 species of spiders. Coccinella septempunctata Linneaus, Cheilomenes sexmaculata (Fabricius) and Brumoides suturalis (Fabricius), Serangium parcesetosum Sicard, Chrysoperla zastrowi sillemi (Esben-Peterson), Zanchius breviceps (Wagner), Geocoris sp. and spiders were most commonly recorded predators. Out of these, Chrysoperla was the predominant species. Encarsia lutea (Masi) and Encarsia sophia (Girault & Dodd) were the two parasitoids that emerged from whitefly pupae. The mean parasitization of whitefly by Encarsia spp. in different cotton growing areas of Punjab was 5.20 per cent (range = 1.5 to 9.1 %).