2nd Instars Research Articles

EFFECTIVENESS OF TRANSGENIC BT MAIZE TO CONTROL Helicoverpa armigera (LEPIDOPTERA: NOCTUIDAE)

The caterpillar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), identified in Brazil in 2013, greatly worries farmers because of its destructive power. The technology of transgenic plants that induces resistance to insects is a great ally for controlling caterpillars. In this study we compared the performance of transgenic Bt maize in the controlling of different larval instars of H. armigera in semi-field seedlings. There were tested the following genotypes: (1) Non-Bt maize Iso-hybrid (Control); (2) Cry1F; (3) Cry1F+ Cry1A.105 + Cry2Ab2; (4) Cry1A.105 + Cry2Ab2; (5) Cry1Ab + Cry1F; (6) Cry1Ab + Vip3Aa20. The experimental design was organized in randomized blocks with eight replications, each consisting of a pot with 5 plants artificially infested with larvae of 2nd, 3rd or 4th instar. At 1, 3, 7, 10 and 14 days after infestation, plants were evaluated for defoliation. In the 3rd instar larvae bioassay, there was high predation by birds, but until seven days after infestation all transgenic maize were efficient to the pest. All transgenic Bt maize were effective in the control of tested H. armigera larvae instars.

Bio-Fabrication of ZnO-CuO Nanoporous Composite and Its Application as Nanolarvicidal Agent for Malaria Vectors

Bio-fabrication of ZnO-CuO nanoporous composite was successfully synthesized using Gum Arabic. The morphology, elemental composition, surface plasmon resonance and functional groups bonds of the ZnO-CuO nanoporous composite were confirmed by SEM, EDX, UV-Visible and FTIR techniques respectively. Nanolarvicidal activity of ZnO-CuO nanoporous composite was tested against 1st, 2nd, 3rd, and 4th instars of malaria vectors for 24 hours using different concentrations. The lethal concentrations (LC50) of ZnO-CuO nanoporous composite against 1st, 2nd, 3rd, and 4th instars were found to be 8.841, 8.734, 8.963 and 10.557 mg/L respectively. Whereas, the LC90 of ZnO-CuO nanoporous composite against 1st, 2nd, 3rd, and 4th instars were found to be 19.062, 28.063, 40.888 and 79.567 mg/L respectively. For all instars, the correlation coefficients were found in the range of 0.945 to 0.999 and it indicates concentration dependent larvicidal activity. It was observed that the lower the instar, the higher the larvicidal activity and conversely. Therefore, ZnO-CuO nanoporous composite could be used as nanolarvicidal agent especially for malaria vectors.

Retention of Pantoea agglomerans Sc1R across stadia of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae).

Southern green stink bug [Nezara viridula (L.)] adults and other pentatomid pests can transmit pathogens (e.g., the bacterium Pantoea agglomerans) that cause disease in cotton (Gossypium hirsutum L.) and other high-value cash crops worldwide. First instars of N. viridula were recently shown to ingest P. agglomerans strain Sc1R with rifampicin-resistance, and to retain the pathogen to the 2nd instar. The objective of this study was to determine the acquisition of P. agglomerans Sc1R by early instars of N. viridula and determine persistence of P. agglomerans Sc1R across subsequent stadia. In three trials, early instars (1st and 2nd) were exposed to P. agglomerans Sc1R and subsequently maintained to adulthood; cohorts were sampled at 3rd and 5th instars, as well as adults. In every trial, P. agglomerans Sc1R was detected in all stadia, including adults, but significantly higher frequencies of infection than expected were observed at the initial stage of infection (either 1st or 2nd instar). Higher densities of P. agglomerans Sc1R were detected in 1st and 2nd instars, and lower densities were observed in subsequent stadia. Densities of innate microbiota were generally lower when the initial stage of exposure was at 1st instar than when the initial stage of exposure was at the 2nd instar. Overall, half of the adults possessed P. agglomerans Sc1R. These findings demonstrated that N. viridula nymphs can acquire P. agglomerans Sc1R and retain the pathogen to adulthood. Potential avenues of research to further elucidate the implications of nymphs harboring pathogens to adulthood are discussed.

Modeling of the effect of temperature on developmental rate of common green lacewing, Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae)

BackgroundThe common green lacewing Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae) is a polyphagous and efficient predatory species commonly found in a wide range of agricultural habitats. It plays an important role in biological control of pests.Main bodyThe effect of temperature on developmental rate of the predator C. carnea was studied at 7 constant temperatures, 15, 20, 25, 27, 30, 32, and 35 °C, 50 ± 10% RH, and a photoperiod of 16:8 h (L:D). Six nonlinear models were evaluated to determine the trend of developmental rate of the predator in examined temperatures and to estimate thermal thresholds of development. Nonlinear models were evaluated based on coefficient of determination (R2), adjusted coefficient of determination (R2adj), residual sum of squares (RSS), and Akaike information criterion (AIC), beside biological significance of the estimated values for the model parameters. Among evaluated nonlinear models, Lactin-2 for all immature stages was the best-fitted model on observations, considering statistical criteria and biological significance of the estimations. The values of the lower temperature threshold by using Lacin-2 were 9.90, 10.90, 11.90, 11.40, 11.11, 11.61, and 11.30 °C for incubation period, 1st, 2nd, and 3rd larval instars, overall larval period, and pupal and total immature stages, respectively. The values of the upper temperature threshold for the mentioned developmental stages were 33.82, 37.66, 33.14, 34.04, 33.58, 32.14, and 32.18 °C, respectively. Estimated values for the optimal temperature for incubation period, 1st, 2nd, and 3rd larval instars, overall larval period, and pupal and total immature stages were 30.69, 30.22, 30.90, 30.34, 30.90, 31.75, and 31.72 °C, respectively.Short conclusionThe results, in addition to determine thermal tolerance for the development of C. carnea, provided advantage information for better use of C. carnea in biological control programs.

Effects on Growth of Ectropis grisescens Warren under Illumination

The 2nd and 5th instar of Ectropis grisescens Warren larvae were exposed to 400~405 nm illumination for 0, 60, 90, 120, 150 or 180 min to determine the effects of the irradiation on the development time as well as the rates of pupation, pupa emergence, aberration rate, eclosion rate, adult longevity and oviposition rate. The results showed that, as compared with control, as the processing time increases, the developmental duration was significantly shortened with 5 instar of E.grisescens Warren larvae. The eclosion rate and aberration rate were significantly increased. At the same time, the pupa weight was significantly higher than that of the 2nd instar larvae. The mortality increased significantly in 2nd of E.grisescens Warren larvae. There was no difference in adult eclosion rate between the two groups, and there was also no difference in the average oviposition. There was no significant difference between the two groups under 400~405 nm illumination, Male adults live longer than female adults.

Preliminary in Vitro Tests for Microwaves as a Post-harvest Disinfestation Treatment on Fruit Flies

In vitro preliminary tests executed to evaluate the possibility of using microwave to disinfest fruits as a postharvest quarantine treatment using a cocking microwave oven. Subjecting the eggs, 1st, 2nd and 3rd larval instars of both medfly and peach fruit fly for 10, 15, 25 and 30 seconds and estimate the mortality percentage. Results revealed that there were a gradual increase in mortality percentage for the larval instars for both flies, eggs and larval instars of peach fruit flies have a higher heat tolerance than medfly stage consequently, lower mortality percentage for the same time period microwave treatments. Also, revealed that eggs of fruit flies (medfly and peach fruit fly) have a higher resistance to heat than larval instars. Thus, Microwave can be a very efficient tool for disinfesting treatments of fruit flies since it can give a very fast rise in temperature in very short time which is a very important parameter in qualifying postharvest quarantine method to avoid fruit damage, still a challenges are presents for developing microwave processes to be applicable as a postharvest quarantine treatment.

Predation Efficacy of Chrysoperla carnea (Steph.) on Parlatoria proteus (Curtis) and Fiorinia phoenicis (Balachowsky) under Semi Field Conditions at Giza Governorate

An experiment was conducted to evaluate the efficacy of Chrysoperla carnea (Steph.) against two hard scale insects Parlatoria proteus (Curtis) and Fiorinia phoenicis (Balachowsky); Hemiptera:Diaspididae, in the nursery of El-Orman Botanical Garden Giza Governorate by releasing 5,10 and 15 individuals of 2nd larval instar of C. carnea and counts were taken 15, 30 and 45 days after treatment. Results showed that there were an effective reduction percentage in population of both scale insects. The mean of reduction percentages after 45 days after treatment in case of P. proteus different stages were 52.54, 68.95 and 77.14% for 1st, 2nd and 3rd treatments, respectively. While mean of reduction percentages of different stages of F. phoenicis recorded 58.38, 59.03 and 65.34% for 1st, 2nd and 3rd treatments, respectively.

FOOD CONSUMPTION AND NUTRITIONAL INDICES OF OAK TASAR WORM ANTHERAEA PROYLEI (JOLLY) FED ON QUERCUS GLAUCA

Studies were conducted under laboratory conditions to evaluate the food consumption and nutritional indices for the development of Antheraea proylei larvae fed on Quercus glauca. Larval duration was 5.4±0.489, 6.4±0.48, 7.2±0.4, 9.8±0.74 and 14.2±0.74 days in the 1st, 2nd, 3rd, 4th and 5th instars, respectively. Larvae consumed a total of 28.85 g insect– ¹ day– ¹, egested 4.164 g insect– ¹ day– ¹ and assimilated 24.69 g insect– ¹ day– ¹ of food provided. 82.3% of tissue growth was observed in the 4th and 5th instar larvae. Approximate digestibility (AD) decreased from 91.94% in the first instar larva to 80.79% in the 5th instar larva. Efficiency of conversion of digested food (ECD) into body tissue and efficiency of conversion of ingested food into growth (ECI) increased from 1st instar larva to 5th instar larva. The result obtained in the present study indicate that Q. glauca could serve as an alternate host plant for rearing A. proylei in areas where the main host plant Q. serrata is not found.

Studies on biology of mango leaf webber Orthaga exvinacea (Hampson)

The laboratory studies on biology of mango leaf webber was conducted at the Department of Entomology, College of Horticulture, Bagalkot during 2018-19. The studies revealed that the mean preoviposition, oviposition and postoviposition periods lasted for 2.60±0.52, 4.10±0.74 and 1.90±0.74 days, respectively. The larva moulted six times by passing through seven larval instars. The mean durations of 1st, 2nd, 3rd, 4th, 5th, 6th and 7th instar were 4.80±0.92, 4.65±0.90, 4.41±0.63, 4.16±0.87, 4.52±0.51, 5.20±0.42 and 6.50±0.53 days, respectively with mean total larval period of 42.54±2.53 days. The mean duration of male and female pupal stage were 11.80±0.63 days and 14.30±1.43 days respectively. The mean longevity of adult male and female were 4.10±0.74 days and 5.80±0.42 days, respectively. The total life cycle completed in 58.44±3.90days in male and 62.64±4.59 days in female.

Spinosad ve Farklı Bacillus thuringiensis (Bacillaceae) Suşlarının Hyphantria cunea (Lepidoptera: Erebidae) Larvaları Üzerindeki Etkinliğinin Değerlendirilmesi

In this study, Bacillus thrungiensis aizawai Bonnefoi & de Barjac, 1963 (Florbac), different isolates of Bacillus thuringiensis (Bt) kurstaki Berliner, 1915 (Biobit, Delfin, Rapax, Rebound) and spinosad (Spintor) were assessed for their efficacy against different instars of Hyphantria cunea (Drury, 1773) (Lepidoptera: Erebidae) under laboratory and field conditions in 2019 in Duzce Province, Turkey. Spinosad was the most effective bioinsecticide, followed by Bt aizawai and Bt kurstaki isolates against various instars of H. cunea. In the laboratory, at 96 hour post-treatment, spinosad caused 98% mortality in 2nd and 3rd instars, and 83% mortality in 4th and 5th instars; Bt aizawai caused 98% mortality in 2nd and 3rd instars and 43% mortality in 4th and 5th instars; and Bt kurstaki isolates caused 95% mortality in 2nd and 3rd instars and 51% mortality in 4th and 5th instars. The results from the field study showed similar trends. The older instars were less susceptible to all the tested bioinsecticides than the younger instars, which may be attributable to the phenomenon known as “maturation immunity”. Bacillus thuringiensis kurstaki has already been recommended for management of this pest. Whereas the data indicated that spinosad and Bt aizawai could also be used as bioinsecticides for control H. cunea larvae.

Toxicity of Bacillus thuringiensis against second instar larvae of Spodoptera litura on different host plants

Spodoptera litura is serious pest of many horticultural and agricultural crops. S. litura can cause severe economic loss of crops like cotton, cabbage and okra. Different methods are adopted to control this notorious insect pest throughout the globe but biological control is one of them that proved best against it. In 2019, current study was conducted to check the toxicity of Bacillus thuringiensis on 2nd larval instars under laboratory conditions by using different hosts. Mortality data was recorded at 24, 48 and 72 hours of post treatment. The results showed that maximum mortality was recorded on okra (41.46%) followed by cotton (34.67%) and cabbage (23.87%) after 24 hours. After 72 hours of post treatment, maximum mortality of larvae was observed on Bt treated leaves of cabbage than okra. The results indicated that 100% mortality was recorded on cabbage after 72 hours of treatment. Bt treated cabbage leaves were found most effective with 11.21% mortality while cotton gave least effective results with 9.99%. The current study concluded that microbial control is best approach to control insect pest under laboratory as well as field conditions.

Potential of standard strains of Bacillus thuringiensis against the tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

BackgroundThe tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the key pests of tomato worldwide, causing an estimated crop loss of 80 to 100%. This pest has developed resistance to several pesticides due to overuse, resulting in control failures in the field. The use of biological insecticides as Bacillus thuringiensis that expressed insecticidal proteins can be an alternative tool by insecticides to suppress the pest population.Main bodyLaboratory study investigated the efficacy of standard Bacillus thuringiensis (Bt) strains (4D1, 4D4, 4G1, 4K5 and 4XX4) against T. absoluta. Bioassay was conducted using tomato leaf discs treated with spore crystal lysates prepared from the standard strains, and mortality data was subjected to concentration-mortality probit analysis. The LC50 values for Bt 4D1, Bt 4D4 and Bt 4G1 were 6.10, 6.62 and 8.18 μg/ml for the 2nd instar; 9.90, 10.20 and 11.12 μg/ml for the 3rd instar; and 19.82, 23.16 and 24.54 μg/ml for the 4th instar, respectively, while the Bt 4K5 and Bt 4XX4 were not toxic to T. absoluta.ConclusionThis study suggests that Bt strain 4D1 is effective against different larval instars of the pest and can be used in its management.

Cuticular hydrocarbons as a tool for determining the age of Chrysomya rufifacies (Diptera: Calliphoridae) larvae.

Calliphoridae are one of the most important insect groups encountered as evidence collected from a crime scene. Age determination of the immature stages of these necrophagous flies is an important step toward estimating the time of colonization and inferring a minimum postmortem interval (PMImin ) in most instances. To determine if the cuticular hydrocarbons could be used to establish whether the development stages yield characteristics profiles, allowing for age estimation, hydrocarbons were extracted from 1st and 2nd, as well as feeding and post-feeding 3rd instar Chrysomya rufifacies, the hairy maggot blow fly. Extracted hydrocarbons were analyzed using gas chromatography coupled to mass spectrometry with the aim to investigate the changes in chemical profiles of each larval stage. A total of 23 compounds were identified with most of them being alkanes (65%) with carbon chain lengths of 9-33 carbons, alkenes (18%), and methyl-branched alkanes (17%). All the hydrocarbons except pentadecane (C15), hexadecane (C16), and nonacosane (C29) showed significant differences in their expression throughout larval development. For 1st instars, nonane was the most abundant (17% of the total hydrocarbons content) compound. Accounting for 11% and 10% of the cuticular hydrocarbons, tricosane and pentacosane, respectively, were the notable hydrocarbons in 2nd instars. For post-feeding 3rd instars, hentriacontane and tritriacontane were present with relative abundances 18% and 15%, respectively. On average, there was a shift from low to high molecular weight hydrocarbons as the larvae aged. These results indicate the change in hydrocarbons makeup as larvae age and could potentially be used to determine the age of immature C.rufifacies and hence aid in PMImin estimations. However, future research is needed to validate these results under natural conditions in the field.

Avaliação de fungos no controle da mosca-das-frutas na preservação do mercado brasileiro de frutas

O controle biológico, com a utilização de fungos entomopatogênicos, tem sido umas das promissoras alternativas no controle de moscas-das-frutas. Este estudo teve como objetivo avaliar a patogenicidade dos fungos entomopatogênicos das espécies Metarhizium anisopliae (Metsch.) Sorok. e Beauveria bassiana (Bals.) em larvas de 2º e 3º instar, pupas e adultos da mosca-das-frutas Ceratitis capitata Wiedemann (Diptera: Tephritidae). O experimento foi conduzido nos Laboratórios de Zoologia de Invertebrados e de Fitopatologia do Centro de Ciências Agrárias, Universidade Federal da Paraíba, no município de Areia - PB. Neste estudo foram utilizados dois isolados, Metarhizium anisopliae IDCB425 e Beauveria bassiana IDCB66, em diferentes concentrações. Verificou-se que o potencial de infecção de ambos isolados é maior em larvas de 2º e 3º ínstares e de adultos de C. capitata, do que em pupas. A taxa de mortalidade de C. capitata aumenta à medida que as suspensões se tornam mais concentradas. O isolado de IDCB66 de B. bassiana é mais eficiente à C. capitata, que o isolado IDCB425 de M. anisopliae.

Comparative toxicity of certain insecticides against Chrysoperla Spp. (Neuroptera: chrysopidae) under laboratory conditions

Toxicity of newer insecticides viz., chlorantraniliprole 18.5 SC, flubendiamide 20 WG, buprofezin 25 SC, lambda cyhalothrin 9.5 + thiamethoxam 12.6 ZC, lambda cyhalothrin 5 EC, azadirachtin 5 w/w, thiamethoxam 25 WG, thiachloprid 21.7 SC were tested against different larval stages of Chrysoperla spp. under laboratory conditions. The observations on percent mortality of 1st, 2nd and 3rd instar of C. spp. larvae were recorded after 24, 48 and 72 hrs of application. The results showed that lambda cyhalothrin + thiamethoxam was found toxic to all instars of Chrysopa larvae whereas azadirachtin was found safest insecticide against all instar of Chrysopa larvae at all treatment intervals. Considering ecofreindliness, it can be concluded that insecticides azadirachtin, buprofezin and flubendiamide were found most safer to all instars of C. spp. which can be taken successfully in the IPM programmes whereas, lambda cyhalothrin + thiamethoxam was found most harmful to all instars of larvae.

Biology, predatory potential and functional response of Mallada desjardinsi (Navas) on melon aphid, Aphis gossypii glover

This study evaluated the developmental biology, predatory potential, and functional response of Mallada desjardinsi (Neuroptera:Chrysopidae) larval instars fed on melon aphid, Aphis gossypii Glover. The experiment was carried out under laboratory conditions at 25 ± 1 °C, with 70 ± 5% R.H and 12:12 L:D photoperiod. The freshly emerged larvae were reared individually in the Petri plates containing moist blotting paper and cucumber leaves (6 × 6 cm) infested with assorted population of second and third instars of A. gossypii. The results showed that incubation, total larval, pre pupal and pupal periods of M. desjardinsi were 2.90, 12.50, 1.40 and 9.10 days, respectively. Pre oviposition, oviposition and post oviposition period of M. desjardinsi was 11.80, 32.40 and 2.76 days, respectively and each female laid an average of 128.58 eggs. The 1st, 2nd and 3rd instars of M. desjardinsi on an average consumed 30.98, 107.80 and 265.40 aphids, whereas total consumption during life cycle was 298.50 aphids/predator. All the three larval stages of the predator exhibited Type II functional response to the aphid. Based on Rogers’s random predator equation, the predator’s attack rate was the lowest (0.092) in the first instar, while the 3rd instar recorded the highest rate (0.118). Functional response parameters indicate that attack rate increased and handling time decreased with the advancement of the predator stage. From biological control point of view, our data suggest the successful use of M. desjardinsi third instar larvae as voracious feeders in IPM programmes against melon aphid.

Pathogenicity of ENTOMOPATHOGENIC nematodes against cabbage butterfly (PIERIS BRASSICAE) LINNAEUS (LEPIDOPTERA: PIERIDAE) in laboratory conditions

Cabbage butterfly (Pieris brassicae) is major pest of cabbage. More than 50% yield losses have been attributed due to this pest annually. Seven insect parasitic nematodes i.e. Steinerma carpocapsae, S. feltiae, S. Pakitananese, S. asiaticum, S. glaseri, Heterorhabditis bacteriophora and H. indica were evaluated on 4th larval instar of P. brassicae at the different concentrations. Two best performing EPNs (S. glaseri and H. bacteriophora) were selected and evaluated against 2nd, 3rd and 4th larval instars of Pieris brassicae at 1500 infective juveniles/ml. H. bacteriophora spp. and S. glaseri spp. were sprayed at 1500 IJs/ml on the cabbage leaves alone or in combination (S. glaseri + H. bacteriophora) and 2nd, 3rd and 4th larval instars were fed on them. Among seven EPNs, hundred percent mortality of P. brassicae was recorded in the case of H. bacteriophora and S. glaseri at1500 IJs/ml concentration after 48 h. Both EPNs spp. were found highly effective against all larval instars of P. brassicae. After 48 h of exposure of both EPNs spp. on all larval instar, 100% mortality was recorded. The combined application of H. bacteriophora + S. glaseri on cabbage leaves resulted into 100% mortality of all larval instars of P. brassicae. From present study, it may be concluded that H. bacteriophora and S. glaseri at 1500 IJs/ml concentration found very effective against P. brassicae in laboratory conditions and may be used in the field conditions.

Konservasi Kupu-kupu Papilio demoleus Linn. (Lepidoptera: Papilionidae) dengan Teknologi Makanan Buatan

The purpose of the research is to study and increase of lime butterfly (Papilio demoleus L.) population used artificial diets, then avoid endangered species status of butterfly in nature. For the future, result of research giving more information about mass rearing techniques of P. demoleus butterflies using artificial diet. P. demoleus larvae and pupae were collected from pomelo (Citrus maxima L.) in the yard of communities in the Pattunuang Resort, Maros district, South Sulawesi. The pomelo leaves as the main food source of P. demoleus larvae taken from the farm around Bontomate'ne village, Pangkep district, South Sulawesi. The experimental activities were conducted in the Pest Laboratory, Pests and Plant Diseases Department, Faculty of Agriculture, Hasanuddin University from February to April 2019. The treatment for P. demoleus larvae were: P0 = fresh pomelo leaves (control); P1 = 35% red bean flour + 35% pomelo leaves + 30% vitamin, water agar, and other ingredients; P2 = 25% red bean flour + 25% soybean flour + 25% pomelo leaves + 25% vitamin, water agar, and other ingredients. Ten 2nd instar of P. demoleus larvae were placed in the plastic containers (diameter = 8 cm, height = 6 cm) covered with gauze, respectively. The fresh pomelo leaves given in whole form, while artificial diet in gel form given as much as 5 g for each larvae in the container. Every day the container was cleaned from food and larvae faeces. The experiments were arranged in Randomized Block Design with four treatments and ten replications. The result was showed P0 is the highest number increasing body weight of P. demoleus larvae. The second highest result increasing P. demoleus body weight was showed by P2 since 2nd instar (0.74 g) until four instar (0.87 g). Observation body length of P. demoleus, P0 was showed the highest number increasing the parameter. The second highest result of body length was showed at P2 started 2nd instar (0.24 cm) through four instar (1.72 cm). Findings at sex ratio and survival, P0 was showed the highest number adult of P. demoleus (8 individual), P2 (3 individual) and P1 (1 individual), respectively. The highest sex ratio of female P. demoleus resulted by P0 (3 individual), P2 (1 individual), respectively. The conclusion is : P2 made from red bean flour + soy bean flour + leaves of pomelo increasing body weight and length of P. demoleus larvae. P1 (red bean flour + leaves of pomelo) treatment was showed the lowest number in development of P. demoleus.

Effect of Water Temperature on Survival, Growth and Molting Cycle During Early Crablet Instar of Mud Crab, Scylla paramamosain (Estampador, 1950)

This study aimed to determine the effect of rearing water temperature on survival, growth and molting cycle of the mud crab, S. paramamosain from Megalopa up to 1st crablet instar (Crablet 1) and from Crablet 1 to 2nd crablet instar (Crablet 2). Different water temperature regimes were implemented i.e. 20 °C, 24 °C, 28 °C, 32 °C, 36 °C and ambient temperature. The observed parameters were: successful molting from Megalopa to Crablet 1 and from Crablet 1 to Crablet 2, survival in Crablet 1 and Crablet 2, growth (carapace increment of crablets), Specific Growth Rate of carapace width (SGRCW) and, molting interval (in days) from Megalopa to Crablet 1 and from Crablet 1 to Crablet 2. The results showed that the highest survival rate from Megalopa to Crablet 1 was found at 24 and 28 °C where both could reach up to 100%. At water temperature of 32 °C and ambient temperature, the survival rate were 96.66%. The lowest survival rate was found at 20 °C and 36 °C treatments (p 0.05), but there were significant differences in molting intervals (p < 0.05) for both Megalopa to Crablet 1 and Crablet 1 to Crablet 2 phases. Treatment of ambient temperature (27–30 °C) had the fastest molting interval from Megalopa to Crablet 1 but its value not significantly different with treatment of 24, 28 and 32 °C. The fastest molting interval from Crablet 1 to Crablet 2 was found at 32 °C which was 2.96 days (p < 0.01). Based on this study, it is recommended that rearing from Megalopa to Crablet 1 should take place at a temperature of 28 °C while, in Crablet 1 to Crablet 2 phase, a temperature of 28 to 32 °C is recommended.

Insecticidal effects of some essential oils against box tree moth (Cydalima perspectalis Walker (Lepidoptera: Crambidae))

The box tree moth Cydalima perspectalis (Walker) (Lepidoptera: Crambidae) is one of the most alien insects found in the Buxus areas of Georgia and World. Many methods have been used to control this pest up to now. But, the problem is still going on. In this study, insecticidal effects of the essential oils obtained from plants Artemisia absinthium L., Seriphidium santonicum (L.) Sojak, Seriphidium spicigerum (K.Koch) Poljakov, Cuminum cyminum L., Mentha pulegium L., Origanum majorana L., Origanum onites L., Origanum syriacum L., Origanum vulgare L., and Satureja hortensis L. on C.perspectalis were tested in laboratory conditions. In this context, larvae of the 2nd and 5th instars of C.perspectalis were exposed to essential oils at doses of 10, 15 and 20 μl/petri for 24, 48, 72 and 96 h. All of the essential oils used in the study caused mortality at different rates; the highest effect on 2nd and 5th instar larvae of C.perspectalis was obtained with the essential oil from O.onites with a mortality rate of 80.0–71.6%. The oils from O. onites (73.3–65.0%), O.syriacum (73.3–63.3%), O.majorana (71.6–66.6%), A.absinthium (68.3–61.6%), S.santonicum (68.3–60.0%), S.spicigerum (66.6–60.0%), S.hortensis (66.6–61.1%), C.cyminum (58.3–53.3%) and M.pulegium (51.6–45.0%) followed this in this order. As a results of the dose effect tests conducted in the second part of the study, the most toxic plant essential oils were determined to be from O.vulgare and the lowest toxic effect from M.pulegium based on LD50 and LD90. The results obtained show that the essential oils from O.vulgare can be used in the control against C.perspectalis.