2nd Larval Instars Research Articles

Effects of interactions among Metarhizium anisopliae, Bacillus thuringiensis and chlorantraniliprole on the mortality and pupation of six geographically distinct Helicoverpa armigera field populations

A local isolate of Metarhizium anisopliae (Hypocreales: Clavicipitaceae), Bacillus thuringiensis subsp. kurstaki and chlorantraniliprole were assessed against six field populations of tomato fruitworm Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) in a series of laboratory bioassays. Two dose rates of B. thuringiensis (0.5, 1 μg g−1), one of both M. anisopliae (1.3 × 106 conidia ml−1) and chlorantraniliprole (0.01 ppm) were applied alone and in combination with each other against 2nd, 3rd, 4th and 5th larval instars. The mortality was observed every 24 h until pupation. The bioassays were carried out at 25°C and 75% r.h. The highest mortality was observed in Rawalpindi with the lowest pupation rate by applying the combined concentrations of B. thuringiensis and chlorantraniliprole. The lowest mortality was observed in population from Gujranwala among all the tested populations. The antagonistic interaction was noted where the high dose rate of B. thuringiensis was combined with M. anisopliae; however, the remaining interactions enhanced the mortality and reduced the percent pupation. The overall results demonstrated that all the treatments gave significant control of the larval instars of H. armigera. The population from Gujranwala proved least susceptible whereas the one from Rawalpindi was highly susceptible.

Description of the larval instars of Amidorus immaturus (Mulsant, 1842)(Coleoptera: Scarabaeoidea: Aphodiidae)

The morphology of the 1st and 2nd larval instars of A. immaturus (Mulsant, 1842) is described and illustrated here for the first time, with an emphasis on the cephalic capsule, head appendages, legs, and last abdominal segments. The cephalic capsule size was employed to determine the larval instar, while the genital disc was employed to assess the sex of the larvae. The growth and sex ratio of A. immaturus were analyzed.

Host suitability and fitness-related parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae) as a parasitoid of the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae)

The seven age-classes of Trichoplusia ni (Hübner) larvae evaluated in this study as hosts of Campoletis sonorensis indicates that early 2nd larval instar (3–5day-old larvae) of T. ni represents the most suitable host stage for the development of the larval endoparasitoid C. sonorensis. The higher suitability of early 2nd larval instar of T. ni resulted in more parasitised larvae, a higher rate of successful parasitoid emergence, a higher rate of female progeny, and a lower rate of immature parasitoid mortality. The fitness gain of C. sonorensis on late 1st larval instar (2day-old larvae) and late 2nd larval instar –early 3rd instars (6–8day-old larvae) stages of T. ni is negatively affected by the trade-offs between the different physiological and behavioral characteristics influencing their suitability as hosts of C. sonorensis.

Pathogenicity of some isolates of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorokin on 2nd and 4th larval instars of Colorado potato beetle, Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae), under laboratory conditions

This study was conducted with the aim of isolating and identifying endophytic bacteria associated with bananas in Kenya and assessing their functional potentiality as biological fertilizers. Banana material was collected from two different banana cultivars in five different geographical regions and bacteria were isolated using five different isolation media. Whole-cell matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) analysis was used for microorganism profiling. Protein from the living cells were extracted using the ethanol/formic acid extraction procedure and intact molecular weights of the ionized proteins directly measured and the pattern of the protein molecular weights used as fingerprints. Forty three isolates were selected for partial 16S rRNA gene sequencing. Isolates were characterized on the basis of their in-vitro plant growth-promoting activities that included abilities to fix free nitrogen, solubilize phosphates and produce siderophores. The isolates were identified as Serratia, Pseudomonas, Rahnella, Enterobacter, Raoultella, Yokenella, Bacillus, Klebsiella, Yersinia and Ewingella species. Siderophore production activity was detected with all the Pseudomonas isolates as determined on blue Chrome Azurol S (CAS) agar plates. Twenty seven isolates were observed to solubilize phosphates, with Rahnella isolates showing the highest potential as determined on NBRIP growth medium. All the isolates grew on solid nitrogen-source free medium, suggesting their ability to fix nitrogen. In conclusion, endophytic bacteria of bananas in Kenya were isolated and identified, and Rahnella and Pseudomonas isolates proposed as potential microbial biofertilizers for sustainable banana production in Kenya.

Divergence of larval resource acquisition for water conservation and starvation resistance in Drosophila melanogaster

Laboratory selection experiments have evidenced storage of energy metabolites in adult flies of desiccation and starvation resistant strains of D. melanogaster but resource acquisition during larval stages has received lesser attention. For wild populations of D. melanogaster, it is not clear whether larvae acquire similar or different energy metabolites for desiccation and starvation resistance. We tested the hypothesis whether larval acquisition of energy metabolites is consistent with divergence of desiccation and starvation resistance in darker and lighter isofemale lines of D. melanogaster. Our results are interesting in several respects. First, we found contrasting patterns of larval resource acquisition, i.e., accumulation of higher carbohydrates during 3rd instar larval stage of darker flies versus higher levels of triglycerides in 1st and 2nd larval instars of lighter flies. Second, 3rd instar larvae of darker flies showed ~40h longer duration of development at 21°C; and greater accumulation of carbohydrates (trehalose and glycogen) in fed larvae as compared with larvae non-fed after 150h of egg laying. Third, darker isofemale lines have shown significant increase in total water content (18%); hemolymph (86%) and dehydration tolerance (11%) as compared to lighter isofemale lines. Loss of hemolymph water under desiccation stress until death was significantly higher in darker as compared to lighter isofemale lines but tissue water loss was similar. Fourth, for larvae of darker flies, about 65% energy content is contributed by carbohydrates for conferring greater desiccation resistance while the larvae of lighter flies acquire 2/3 energy from lipids for sustaining starvation resistance; and such energy differences persist in the newly eclosed flies. Thus, larval stages of wild-caught darker and lighter flies have evolved independent physiological processes for the accumulation of energy metabolites to cope with desiccation or starvation stress.

EFFICIENCY OF TWO NOVEL BIOTIC COMPOUNDS AGAINST THE LABORATORY AND FIELD STRAIN OF THE COTTON LEAFWORM, Spodoptera littoralis (Boisd.)

The efficiency of two novel compounds (takumi, and radiant) and conventional insecticide (methomyl) against the second and fourth instars of the laboratory and field strains of Spodoptera littoralis was evaluated under laboratory conditions through determination their LC50 values. Radiant was the most toxic one against both of 2nd and 4th larval instars of the laboratory and field strains. The LC50values were 0.06, 1.95(2nd instar) and 5, 10 ppm (4th instar) of laboratory and field strains, respectively. Takumi was the second one with the LC50values of 0.12, 2.4 and 9.0, 19 ppm for the two instars of both strains, respectively. Lannate was the least one, its LC50values were 5.86, 10 and 46.9, 93.8ppm, respectively. All the treated larvae were biologically affected by the three tested compounds. The effect varied according to the strain, larval instars and tested compound. Therefore, the treated larvae were resulted in decreased pupation and adult emergence percentages. Also, the larval treatment of field strain treated with takumi induced the longest period of the larval duration. While, the 2nd larval instar treatments had the highest effect in the pupal period increase. Hence, the larval treatment of the laboratory strain had the strongest effect in the pupal weight decrease. The 2nd instar of the field strain treated with radiant and the 4th instar of the same strain treated with takumi caused the highest percent of pupal malformations, hence, the 2nd instar of the laboratory strain treated with methomyl and the 4th instar treated with takumi induced the greatest percent of adult malformations. Also, the 4th instar of the field strain treated with takumi had the strongest effect in adult fecundity reduction..

Effect of leaf essential oil of Coccinia indica on egg hatchability and different larval instars of malarial mosquito Anopheles stephensi

Objective To assess the larvicidal and egg hatching inhibition property of the leaf essential oil of Coccinia indica ( C. indica) against Anopheles stephensi ( An. stephensi). Methods The larvicidal potential of C. indica leaf essential oil was evaluated against 1st, 2nd, 3rd and 4th instars larvae of An. stephensi using WHO protocol. The 24h LC 50 and LC 90 values of the essential oil were determined following probit analysis. The egg hatching inhibition activity was also tested at 10, 20, 40, and 60 mg/L. The IC 50 value of essential oil was determined against eggs of An. stephensi. Results The essential oil extracted from C. indica possessed excellent larvicidal and egg hatching inhibition activity against An. stephensi. The bioassays showed LC 50-LC 90 of 54.3-140.3, 65.5-155.6, 86.8-180.7 and 95.3-192.6 for 1st, 2nd, 3rd, and 4th larval instars, respectively. The 50% egg hatching inhibition concentration (IC 50) was noted at 16.5 mg/L. Conclusions The present finding suggest that the C. indica leaf essential oil provided an excellent potential for controlling An. stephensi mosquito at earlier stage of their life cycle.

New Larvicidal Acetogenin from the Red Alga Laurencia papillosa

AbstractA new C15 acetogenin, cyclic enyne (12E)‐cis‐maneonene‐E (1) and (12Z)‐trans‐maneonene‐B (2), together with different secondary metabolites including sesquiterpenoid 2,10‐dibromo‐3‐chloro‐α‐chamigrene (3) and fatty acid aldehydes (4–8) were isolated from the petroleum ether extract of a red alga, identified as Laurencia papillosa, collected from the Saudi Red Sea coast. The L. papillosa crude extract and its active ingredient acetogenin (1) have been evaluated for the ability to control two main economically important pests, the confused flour beetle larvae Tribolium confusum and Culex pipiens mosquito larvae. Compound 1 showed high potential as a natural insecticide against these two pests. In the case of T. confusum larvae, the LD50 values were 0.21 and 0.16% after 6 and 12 days of treatment with crude extract and acetogenin, respectively. On the other hand, the resulting LC50 values of mosquito larvae bioassay were 30.7, 36.9, and 41.8 ppm after 24 h treatment against 2nd, 3rd, and 4th larval instars, respectively. Also, an increase of the insecticidal effects against mosquito larvae was recorded after extending treatment time to 48 h.

HISTOPATHOLOGICAL EFFECT OF CERTAIN HEAVY METALS ON THE MOSQUITO VECTOR CULEX PIPIENS L. (DIPTERA: CULICIDAE)

In the laboratory, histopathological effects of heavy metals in the form of cadmium chloride, copper sulphate, lead nitrate and mercuric nitrate were tested against the adults resulted from the 2nd larval instar of C. pipiens treatment with the LC50s (0.11, 5.1, 45.4 and 0.44ppm ) to study their effect on certain histological organssuch as ovary, testis and fat body. The histological examinations of ovaries in heavy metals-treated C. pipiens females showed a reduction in the number of developed oocytes and degeneration of a great number of oocytes. The highest reduction and damage were induced by Cd and Hg. The present study also showed damage and reduction in spermatogonia and spermatocytes in heavy metals-treated C. pipiens males. The highest reduction and abnormality were caused by Cd and Hg. In addition, the present study showed alteration and abnormality of fat body in heavy metals-treated mosquitoes.It is clear from the results obtained in this study that the presence of such elements in the ecosystem water for Culex mosquitoes as possible to contribute to the reduction of mosquito breeding.

Comparative effectiveness and field persistence of insect growth regulators on a field strain of the cotton leafworm, Spodoptera littoralis, Boisd (Lepidoptera: Noctuidae)

Toxicity effects and field persistence of the insect growth regulators lufenuron, flufenoxuron and triflumuron were assessed in the laboratory using second and fourth larval instars of Spodoptera littoralis. Laboratory bioassays indicated that lufenuron was more effective on both 2nd and 4th larval instars, as well as killing both larval instars faster than flufenoxuron or triflumuron. Field-laboratory experiments were conducted to show direct and residual effects of the tested IGRs in terms of toxicity and stability. They indicated that all the tested insecticides were stable under field conditions and give high percentages of mortality. Overall, lufenuron was more efficient than the other tested insecticides. In addition, it gave a faster kill in some testing periods. Data presented in this work show greater efficiency of lufenuron in controlling S. littoralis than flufenoxuron or triflumuron. Using this insecticide for cotton leafworm control in cotton fields may give better results under field condition.

Effect of Chitin synthesis inhibitors (flufenoxuron) on some biological and biochemical aspects of the cotton leaf worm Spodoptera littoralis Bosid (Lepidoptera: Noctuidae)

The present study aimed to evaluate the biological effect of insect growth regulator flufenoxuron (Cascade) as a chitin synthesis inhibitor against 2nd and 4th larval instars of Spodoptera littoralis, to determine its toxicity. Effect of sublethal doses LC25, LC50 and LC90 were used to investigate the enzymatic activities. The tested IGR significantly increased the larval and pupal durations, on the other hand decrease the percentages of pupation, adult emergency, fecundity and fertility of the eggs produced by the adult progeny. The tested compound significantly induced larval mortalities, which were dose dependant. Treatments of the 2nd and 4th larval instars with the tested IGR induced some morphogenic abnormalities in larval, larval-pupal and pupal stages, as well as pupal-adult intermediate. Some emerged adults have various degrees of malformations. All the treated larvae as 2nd instar showed a high sensitivity to the tested IGRs more than 4th instars. The treated larvae in both 2nd and 4th larval instars with the sublethal doses LC25, LC50 and LC90 showed a significant decrease in enzyme activities of acid phosphatase and the non- specific esterases, α,β esterases at different times intervals post treatments.

Efficacy of leaves extract of Calotropis procera Ait. (Asclepiadaceae) in controlling Anopheles arabiensis and Culex quinquefasciatus mosquitoes

The present study aimed to investigate, the larvicidal, adult emergence inhibition and oviposition deterrent activity of aqueous leaves extract of Calotropis procera against Anopheles arabiensis and Culex quinquefasciatus as natural mosquito larvicide. The larvicidal activity was monitored against 2nd, 3rd and 4th instar larvae of each mosquito species 24 h post-treatment. Adult emergence inhibition activity was tested by exposing 3rd instar larvae of each mosquito species to different concentrations of extracts (200, 400, 600, 800 and 1000 ppm for An. arabiensis and 100, 200, 300, 400, 500 and 600 ppm for Cx. quinquefasciatus). Probit analysis was used to analyze data from bioassay experiments. The oviposition deterrent activity was tested by using three different concentrations of extracts (1000, 500 and 200 for An. arabiensis, and 1000, 500 and 100 for Cx. quinquefasciatus) that caused high, moderate and low larval mortality in the larvicidal experiment against 3rd instar larvae. It was found that, LC50–LC90 values calculated were 273.53–783.43, 366.44–1018.59 and 454.99–1224.62 ppm for 2nd, 3rd and 4th larval instars, respectively, of An. arabiensis and 187.93–433.51, 218.27–538.27 and 264.85–769.13 ppm for 2nd, 3rd and 4th larval instars, respectively, of Cx. quinquefasciatus. Fifty percent of adult emergence inhibition (EI50) was shown at 277.90 and 183.65 ppm for An. arabiensis and Cx. quinquefasciatus, respectively. The pupal stage was not affected till a concentration of 5000 ppm. The extract showed oviposition deterrence and effective repellence against both mosquito species at different concentrations, with the observation on that maximal eggs were laid in low concentration of extract. These results suggest that the leaves extract of C. procera possess remarkable larvicidal, adult emergence inhibitor, repellent and oviposition deterrent effect against both An. arabiensis and Cx. quinquefasciatus, and might be used as natural biocides for mosquito control.

Life Cycle of the Ladybird Beetle. Cheilotnenes lunata Fab. (Coleotera: Coccincllidae), A Potential Biocontrol Agent of the Cowpea Aphid, Aphis croccivora (Koch.) (Homoptera: Aphididae)

The life cycle of the ladybird beetle, Cheilomenes lunata Fab.(Coleoptera: Coccinelidae) on Aphis craccivora Koch was studied under fluctuating laboratory condition of 25 – 32°C and 33 – 73° RH. The average incubation period was 3.2 days with a hatchability of 93.1 %. There were four larval instal’s with developmental duration averaging 3.0, 2.2, 2.2 and 4.2 days for the 1st, 2nd , 3rd and 4th larval instars, respectively. The total larval developmental period ranged from 9.7 – 13.5 days and the pupal period lasted for 4.8 days. Mortality at these stages were 37.6 and 7.5% respectively. Pre-oviposition period averaged 3.7 days. The mean number of eggs per female was 1257.4 and the mean oviposition period was 47.0 days. The longevity of mated males and females averaged 87.9 and 72.1 days, respectively, while those of unmated males and females averaged 80.8 and 61.5 days, respectively. The male to female ratio was 1: 1. Information were given on the moulting process and copulation of the ladybird beetle.

Expression of insulin pathway genes during the period of caste determination in the honey bee,Apis mellifera

Female honeybees have two castes, queens and workers. Developmental fate is determined by larval diet. Coding sequences made available through the Honey Bee Genome Sequencing Consortium allow for a pathway-based approach to understanding caste determination. We examined the expression of several genes of the insulin signalling pathway, which is central to regulation of growth based on nutrition. We found one insulin-like peptide expressed at very high levels in queen but not worker larvae. Also, the gene for an insulin receptor was expressed at higher levels in queen larvae during the 2nd larval instar. These results demonstrate that the insulin pathway is a compelling candidate for pursing the relationship between diet and downstream signals involved in caste determination and differentiation.

Larvicidal and structural studies of some triphenyl- and tricyclohexyltin para-substituted benzoates

Several new triphenyl- and tricyclohexyltin para-substituted benzoates were synthesized. Their structures were characterized by IR and Mössbauer spectroscopies. The structures were determined to be four-coordinated monomers. Larvicidal activities of the new compounds as well as other benzoates were evaluated against the 2nd larval instar of the Anopheles stephensi and Aedes aegypti mosquitoes. Results from the screening studies indicated that the triphenyltin benzoates were more toxic towards the Ae. aegypti larvae. A quantitative-structure activity relationship was also developed for the An. stephensi larvae.

The distribution and habitat of Calomera littoralis mandli (Mandl, 1967) (Coleoptera: Cicindelidae) on the coastal margin of Lake Van in Turkey

The tiger beetle Calomera littoralis mandli was found at Lake Van in eastern Anatolia at 20 out of 47 localities surveyed during 2004–2005. It occurs in open habitats with fine sand mixed with clay or in salt-marshes and with little plant cover. Three groups of larval burrows were determined, with average openings of 1.54 mm, 2.46 mm and 3.80 mm. These correspond to the 1st, 2nd and 3rd larval instars.

Comportamento e ciclo de vida de Epilachna vigintioctopunctata (Fabricius) (Coleoptera, Coccinellidae) em Lycopersicum esculentum Mill. (Solanaceae)

Epilachna vigintioctopunctata (Fabricius, 1775) é praga de diversas plantas de importância agrícola na Ásia. Em 1990 foi encontrada no Brasil, em cucurbitácea próximo a Curitiba, Estado do Paraná. Em fevereiro de 2002, foram coletados em Solanum americanum Mill. (Solanaceae) (maria-preta) em Itajaí, Estado de Santa Catarina. Adultos foram mantidos em ± 24ºC, umidade relativa > 53%, 12 h fotofase e alimentados com folhas de Lycopersicum esculentum Mill. (Solanaceae). A média foi de 24,45 ovos por postura e o período de incubação de 7,14 dias. A viabilidade dos ovos foi de 63,68%. A média do 1º, 2º, 3º e 4º instares larvais foi em média 5,88; 4,62; 5,88 e 9,81 dias, respectivamente. O período larval totalizou em média 26,19 dias e o pupal 8,19 dias. O ciclo de vida durou em média 41,44 dias. O período médio de pré-oviposição, oviposição e pós-oviposição foi respectivamente de 23,57, 17,86 e 53,86 dias e a fecundidade das fêmeas de 59,78 ovos. A longevidade média do macho e da fêmea foi 81,44 e 97,89 dias, respectivamente.

Larvicidal activity of Copaifera reticulata ducke oil-resin against Culex quinquefasciatus Say (Diptera: Culicidae)

The appearance of resistance of Culex quinquefasciatus Say to chemical insecticides and the modification of the susceptibility of this mosquito to pyrethroid has stimulated studies on the activity of plants as alternative for its control. In this study, bioassays were carried out to verify the larvicidal activity of the oil-resin of Copaifera reticulata on C. quinquefasciatus. The bioassays were carried out with the oil dissolved in dimethylsulfoxide (DMSO), at the proportion of 0.4 ml of DMSO to 24.6 ml of distilled water. For each instar, the bioassays were carried out in plastic glasses with 100 ml solution using 20 larvae, wit four replications to adjust the lethal concentrations. The mortality observations were made after 48h exposure of the larvae to the solution. The control was carried out in distilled water and DMSO, with the same number of replications as the bioassays. The experiments were carried out in a biological chamber, controlled at 28 ± 1°C, 80 ± 5% relative humidity and 12h light. The larvae without movement were considered dead. The C. reticulata oil-resin demonstrated larvicide activity for all the C. quinquefasciatus instars. The LC50 found for the 1st, 2nd, 3rd and 4th larval instars were: 0.4, 0.9, 39 and 80 ppm, and the LC99 were 15, 15, 50 and 180 ppm, respectively.

Larval juvenile hormone treatment affects pre-adult development, but not adult age at onset of foraging in worker honey bees ( Apis mellifera)

Previous research has shown that juvenile hormone (JH) titers increase as adult worker honey bees age and treatments with JH, JH analogs and JH mimics induce precocious foraging. Larvae from genotypes exhibiting faster adult behavioral development had significantly higher levels of juvenile hormone during the 2nd and 3rd larval instar. It is known that highly increased JH during this period causes the totipotent female larvae to differentiate into a queen. We treated third instar larvae with JH to test the hypothesis that this time period may be a developmental critical period for organizational effects of JH on brain and behavior also in the worker caste, such that JH treatment at a lower level than required to produce queens will speed adult behavioral development in workers. Larval JH treatment did not influence adult worker behavioral development. However, it made pre-adult development more queen-like in two ways: treated larvae were capped sooner by adult bees, and emerged from pupation earlier. These results suggest that some aspects of honey bee behavioral development may be relatively insensitive to pre-adult perturbation. These results also suggest JH titer may be connected to cues perceived by the adult bees indicating larval readiness for pupation resulting in adult bee cell capping behavior.

Efeito da aplicação de silício em plantas de milho no desenvolvimento biológico da lagarta-do-cartucho Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae)

Este trabalho, objetivou avaliar o efeito da aplicação de silício em plantas de milho no desenvolvimento da lagarta-do-cartucho Spodoptera frugiperda (J.E. Smith). O tratamento com silício consistiu na aplicação de 3,2 ml de solução de silicato de sódio [25-28% (p/v) de SiO2], mais 96,8 ml de água, via solo aos cinco dias, 10, 15, 20 e 25 dias após a emergência de plantas de milho mantidas em vasos. Outro grupo de plantas foi cultivado sem aplicação de silício. Avaliou-se o desenvolvimento de lagartas alimentadas com folhas de milho retiradas de plantas tratadas com silício, em comparação com lagartas alimentadas com folhas de milho não tratadas, registrando-se a mortalidade ao final do 2º ínstar larval, a duração do período larval e pupal, a mortalidade larval e pupal e o peso de pupa. Não se observou efeito do silício na duração da fase larval e pupal, peso de pupa e na mortalidade de pupas. Entretanto, verificou-se maior mortalidade e aumento de canibalismo em grupos de lagartas ao final do 2º ínstar, e maior mortalidade de lagartas individualizadas no 2º e 6º ínstares, quando foram alimentadas com folhas de plantas de milho tratadas com silício, em comparação com a testemunha. Observou-se que as mandíbulas das lagartas, nos seis ínstares, apresentaram desgaste acentuado na região incisora quando em contato com folhas com maior teor de silício. A aplicação de silício pode dificultar a alimentação de lagartas, causando aumento de mortalidade e canibalismo e, portanto, tornando as plantas de milho mais resistentes à lagarta-do-cartucho.