Pupal-adult Intermediates Research Articles

‘Insecticidal efficacy of a hormonal analogue on the post-embryonic development of a flesh fly, Sarcophaga ruficornis (Diptera: Sarcophagidae)’

ABSTRACT Sarcophaga ruficornis (Fabricius 1794) causes myiasis in humans and other vertebrates. It has a wide distribution across tropical countries. In the present investigation, the effect of a juvenile hormone analogue, fenoxycarb has been observed on the last instar larvae of S. ruficornis. The last instar larvae (0, 1 and 2-days old) of this dipteran fly were treated topically with sub-lethal doses (10, 20, 40, 60 and 80 µg/µl/larva) of fenoxycarb. Several effects were observed such as mortality, abnormal pupariation, reduction pupariation, adult emergence and eclosion failure. Pupal-adult intermediates and the emergence of abnormal adults were also observed. Log Inhibitory concentration (LogIC50) causing inhibition of normal pupariation was 1.68, 1.8 and 1.681 µg/µl in 0, 1 and 2-days of larval treatments respectively. Whereas LogIC50 values inhibiting the adult emergence were 1.297, 1.359 and 1.482 µg/µl in 0, 1, and 2-days of larval treatments respectively. Results manifest the potency of fenoxycarb in the control of larval-adult transformation in S. ruficornis.

MicroRNA let-7 is required for hormonal regulation of metamorphosis in the silkworm, Bombyx mori

The heterochronic microRNA let-7, which was first identified in Caenorhabditis elegans, controls the timing of developmental programs, and let-7 triggers the onset of the juvenile-adult transition in bilaterians. The expression of let-7 is strongly induced during the last larval stage of C. elegans and is highly expressed in the late last instar larvae/nymphs of the fly Drosophila melanogaster and the cockroach Blattella germanica. In the silkworm Bombyx mori, the expression of let-7 remarkably increases in the corpus cardiacum-corpus allatum complex (CC-CA) at the beginning of the last larval instar and is maintained at high levels during this instar. To determine the biological function of let-7 in B. mori, we generated a let-7 knockout line and a transgenic UAS-let-7 line. The let-7 knockout larvae were developmentally arrested in the prepupal stage and became pupal-adult intermediates after apolysis. When let-7 was ubiquitously overexpressed under the transcriptional control of an Actin3-GAL4 driver, developmental timing and growth of larvae were severely impaired in the penultimate (L4) instar, and these larvae underwent precocious metamorphosis from L4. Furthermore, our results showed that reception and signaling of ecdysteroids and juvenile hormones (JHs) normally occurred in the absence of let-7, whereas the biosynthesis of ecdysone and JHs were affected by disruption and overexpression of let-7. Together, the present study demonstrates that let-7 is required for the coordination of the biosynthesis of ecdysone and JH to ensure the developmental transition during the metamorphosis of B. mori.

Effect of a novel juvenoid fenoxycarb on the pupal-adult transformation in the blowfly, Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae).

Chrysomya megacephala (Fabricius, 1794) (Diptera, Calliphoridae) acts as a vector of many disease-causing pathogens. It causes myiasis in human beings and other living vertebrates. In the present study, the effect of a juvenile hormone analog (JHA), fenoxycarb, was evaluated on pupal-adult transformation by exposing pupae (0 and 1-day-old) of blowfly. Pupae were topically treated with different concentrations of the compound, viz., 20, 40, and 80µg/µl applied on the posterior dorsum with the help of a micropipette. The effects comprised various developmental aberrations, such as delayed pupal-adult ecdysis duration, pupal mortality, formation of pupal-adult intermediates, eclosion failure, reduced adult emergence, and formation of abnormal adults. The freshly molted pupae (0day) were more susceptible as compared to 1-day-old pupae. Pupal mortality was highest at 80µg. Normal adult emergence was completely inhibited at day 0 pupae treated with 80µg of the fenoxycarb. These results demonstrate that fenoxycarb was capable of successfully inhibiting the pupal-adult transformation, and thus, it can be used to control this myiasis-causing agent.

A steroidal lactone, withaferin A acts as a potential insect growth regulator against polyphagous pest, Spodoptera litura (Lepidoptera: Noctuidae)

Administration of a steroidal lactone, withaferin A to last larval instar of a polyphagous pest, Spodoptera litura caused severe impairment of development resulting into a significant delay in larval–pupal and pupal–adult ecdysis, larval mortality, ecdysial stasis, formation of larval–pupal and pupal–adult intermediates, suppression of pupation and adult emergence and formation of abnormal pupae and adultoids. The LC50 value in topical administration of withaferin A was 180.3 µg·µL−1 against freshly moulted sixth instar larvae of S. litura. This suggests that a bioactive ingredient withaferin A, found in the parts of the medicinal plant, Withania somnifera interferes with the neuroendocrine system of the insects resulting into disruption of moulting and metamorphosis. The active ingredient, withaferin A from W. somnifera may be safely and judiciously employed for the control of S. litura under field conditions along with other bio-rational approaches for insect pest management programs.

Methanolic Extract of Winter Cherry Causes Morpho-Histological and Immunological Ailments in Mulberry Pyralid Glyphodes pyloalis.

The effect of Withania somnifera a medicinal plant seed extract was tested against lesser mulberry pyralid, a potential pest of mulberry. The mulberry leaves were used for silk production in rural areas of northern Iran. The extract was administered orally by leaf dipping method in two lower (5%W/V) and higher (15%W/V) dosages to third instar larvae (<24 h) for biological assays and to fifth instar larvae (<24 h) for Physiological studies. The results showed formation of larvoids (Ls), larval-pupal intermediates (LPIs), pupoids (Ps) and pupal-adult intermediates (PAIs). The results showed increased larval duration by 1.7 and 2 folds in 5 and 15% treatment, respectively. Fecundity of resultant adults was decreased by 1.2 and 1.3 in 5 and 15% treatment, respectively. Except approximate digestibility (AD) and consumption index (CI) all other feeding indices showed reduction. The feeding deterrence was prominent at 15% (87%) and 5% showing 48% deterrence. Our enzymatic and non-enzymatic assessments upon treatment showed reduction in key components, except detoxifying enzymes. However, the activity of an important enzyme involved in cuticle hardening and immunity called phenoloxidase was reduced. We also investigated the histology of midgut for further analysis and found drastic changes in main cellular elements. Immunological changes following treatment was noticeable in reduced Total Hemocyte Count but surprisingly increased Differential Hemocyte Count. However, the hemocytes structure was extremely damaged. The reduced number of eggs in treated but survived adults indicated reduced ovaries, with vacuolization both in trophocytes and oocytes. The key chemical compounds showed reductions particularly at 15%. The present results are concomitant with few earlier studies on this medicinal plant and deserve further studies particularly in deriving key chemicals that alter metamorphosis similar to insect growth regulators.

Toxicity and insect growth regulatory effects of root extract from the medicinal plant, Withania somnifera (Linnaeus) against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

The insect growth regulatory effects of the medicinal plant, Withania somnifera (Family: Solanaceae) on the moulting and metamorphosis of economically important stored grain pest, Tribolium castaneum (Coleoptera: Tenebrionidae) were assessed under laboratory conditions. Seventh instar larvae of the red flour beetle, T. castaneum were topically treated with different doses of root extract of W. somnifera. Treatment with root extract of W. somnifera disrupted growth, development, moulting and metamorphosis in T. castaneum. The results included mortality, prolongation of larval-pupal and pupal-adult ecdysis, ecdysial stasis, development of larval-pupal and pupal-adult intermediates and adultoids, eclosion inhibition, reduced pupation and adult emergence. The LC50 value in topical application of root extract of W. somnifera was 0.5850 µg·µL−1 against last instar larvae of T. castaneum. These results are similar to those observed by the application of juvenile hormone analogues and may be due to interference with the normal hormonal mechanism of moulting and metamorphosis.

Sensitivity of tobacco caterpillar, Spodoptera litura, to extract from a medicinal plant, Withania somnifera

ABSTRACTThe larval stage of a polyphagous moth Spodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco caterpillar, causes loss in many vegetables. Use of chemical pesticides to control this pest has resulted in environmental pollution, is hazardous to non-target organisms, and contributes to development of pest resistance against these compounds. Alternatives for pest management need to be developed. Extracts derived from plants can function as insect growth regulators and are easily biodegradable. Topical administration of root extracts from a medicinal plant, Ashwagandha (Withania somnifera L. Dunal), to sixth instar larvae and freshly molted pupae (0–2 h old) of S. litura caused prolongation of larval-pupal and pupal-adult ecdysis duration, mortality, reduced pupation, and adult emergence. Root extracts of W. somnifera produced the morphological and developmental abnormalities like ecdysial failure, formation of larval-pupal and pupal-adult intermediates, abnormal pupae and adultoids. Treatment with root extracts of W. somnifera was more toxic to pupae compared to larvae of S. litura. The results may be due to interference with normal hormonal mechanism eventually leading to disruption of molting and metamorphosis.

Growth regulatory and growth inhibitory effects of Thevetia neriifolia stem extracts on Helicoverpa armigera (Lepidoptera: Noctuidae)

Helicoverpa armigera, a serious global destructive pest of agricultural crops, is on continuous rise despite several control measures undertaken. The detrimental effects of these measures have created a dire need to explore alternate eco-safe strategies. The present study investigates the growth-regulatory and growth-arrest potential of hexane and methanol extracts of Thevetia neriifolia stems against H. armigera. Investigations revealed that larval feeding and rearing on the extract-containing diet did not result in appreciable larval mortality but delayed the larval growth and development. Both the extracts demonstrated dose-dependent effects exhibiting negative correlation between the weights gained by developmental stages and the extract concentrations. Feeding with extracts also resulted in formation of few larval–pupal and pupal–adult intermediates and significantly reduced percent adult emergence of H. armigera. Current study, however, revealed higher growth inhibitory potential of methanol extracts as compared with hexane extracts. The study attempts to provide an eco-friendly approach for H. armigera management.

Bioefficacy of root extracts of a medicinal plant, Withania somnifera (Dunal) against a polyphagous pest, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

Oral administration of root extracts of a medicinal plant, Ashwagandha (Withania somnifera) to last instar larvae of a polyphagous pest, Spodoptera litura resulted into abnormal morphogenesis and the effects comprised mortality, delay in larval-pupal and pupal-adult ecdysis, ecdysial stasis, formation of larval-pupal and pupal-adult intermediates, reduced pupation and formation of abnormal pupae, complete suppression of normal adult emergence and formation of adultoids. These effects are similar to those produced by the administration of JHAs and may be due to interference with the normal hormonal mechanism of moulting and metamorphosis.

Structural and functional characterization of proteinase inhibitors from seeds of Cajanus cajan (cv. ICP 7118)

Proteinase inhibitors (C11PI) from mature dry seeds of Cajanus cajan (cv. ICP 7118) were purified by chromatography which resulted in 87-fold purification and 7.9% yield. SDS-PAGE, matrix assisted laser desorption ionization time-of-flight (MALDI-TOF/TOF) mass spectrum and two-dimensional (2-D) gel electrophoresis together resolved that C11PI possessed molecular mass of 8385.682 Da and existed as isoinhibitors. However, several of these isoinhibitors exhibited self association tendency to form small oligomers. All the isoinhibitors resolved in Native-PAGE and 2-D gel electrophoresis showed inhibitory activity against bovine pancreatic trypsin and chymotrypsin as well as Achaea janata midgut trypsin-like proteases (AjPs), a devastating pest of castor plant. Partial sequences of isoinhibitor (pI 6.0) obtained from MALDI-TOF/TOF analysis and N-terminal sequencing showed 100% homology to Bowman-Birk Inhibitors (BBIs) of leguminous plants. C11PI showed non-competitive inhibition against trypsin and chymotrypsin. A marginal loss (<15%) in C11PI activity against trypsin at 80 °C and basic pH (12.0) was associated with concurrent changes in its far-UV CD spectra. Further, in vitro assays demonstrated that C11PI possessed significant inhibitory potential (IC50 of 78 ng) against AjPs. On the other hand, in vivo leaf coating assays demonstrated that C11PI caused significant mortality rate with concomitant reduction in body weight of both larvae and pupae, prolonged the duration of transition from larva to pupa along with formation of abnormal larval-pupal and pupal-adult intermediates. Being smaller peptides, it is possible to express C11PI in castor to protect them against its devastating pest A. janata.

EFFICACY OF SOME IGRs FOR THE CONTROL OF PEACH FRUITFLY, BACTROCERA ZONATA (SAUNDERS) (DIPTERA: TEPHRITIDAE)

Peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae), has been recognized as a serious insect pest during the last decade attacking a wide range of fruits in Egypt. The potential of some insect growth regulators, Pyriproxyfen, Methoxyfenozoide and Novaluron to cause fatal hormonal disorders in immature stages, full grown larvae and 1-day old pupae, of B. zonata in sandy soil was studied under laboratory conditions. In addition, morphogenetic activity as larval-adult and pupal-adult intermediates of B. zonata resulting from IGRs treatment was recorded. Results indicated that, LC50 for full grown larvae were 0.96, 11.40 and 64.0 ppm in case of Pyriproxyfen, Novaluron and Methoxyfenozoide, respectively. The LC50 values for 1-day old pupae of B. zonata were 4.50 and 3200 ppm for Pyriproxyfen and Novaluron respectively, while Methoxyfenozoide has no fatal effect on 1-day old pupae of B. zonata. On the other hand, the EC50 values of full grown larvae were 1.31, 16.8 and 550 ppm for Pyriproxyfen, Methoxyfenozoide and Novaluron, respectively. The EC50 values for 1-day pupae were 2.80, 1450 and 5000 ppm, for the same compounds, respectively. The obtained results proved that, Pyriproxyfen is a promising candidate for the control of the peach fruit fly.

Insect Growth Inhibitory Activity of Clerodane Diterpenoids Isolated from Clerodendron infortunatum L. on the Cotton Bollworm, Helicoverpa armigera (Hubner)

Three clerodane diterpenoids were isolated from the medicinal plant, Clerodendron infortunatum and their growth inhibitory activity was evaluated against Helicoverpa armigera through topical as well as diet incorporation method and the results compared with azadirachtin technical (20 %). Different parameters were used to assess the growth inhibitory effects, such as larval mortality, pupal mortality, larval–pupal intermediates, abnormal pupae, pupal–adult intermediates, larval and pupal weight reduction and larval and pupal durations. The growth inhibition activity in the present study was compared based on growth inhibition index (GI50). It was observed that through topical application clerodin (1), 15-methoxy-14,15-dihydroclerodin (2) and 15-hydroxy-14,15-dihydroclerodin (3) showed 13, 21 and 11 ppm GI50 values, respectively, compared to azadirachtin with GI50 value of 15 ppm. Through diet incorporation method, azadirachtin showed complete growth inhibition even at the lowest concentration (10 ppm) and more than 50 % growth inhibition was recorded at the lowest concentration of the pure compounds. Results showed that C. infortunatum can be considered as an important plant to develop botanical biopesticides. Effect of isolated compounds on various parameters of insect growth inhibition is discussed.

Insect Growth Regulating Activity of Phytochemical (+)-O- Methylarmepavine, Against the Stored Pulse Pest Callosobruchus Chinensis

Topical application of (+)-O-Methylarmepavine isolated from the leaves of Annona squamosa caused inhibition of growth and development of fifth instar larvae of red gram beetle Callosobruchus chinensis. There was production of larval-pupal intermediates and pupal-adult intermediates and adults with various ovarian abnormalities.

LARVICIDAL AND ADULT EMERGENCE INHIBITION ACTIVITY OF ABUTILON INDICUM (LINN.) (MALVACEAE) LEAF EXTRACTS AGAINST VECTOR MOSQUITOES (DIPTERA: CULICIDAE)

ABSTRACT The crude leaf extracts of Abutilon indicum were evaluated for larvicidal, pupal deformities and adult emergence inhibition activity against vector mosquitoes viz., Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. Larvicidal activity was carried out using WHO protocol. Hexane extract with LC50 value of 261.31 ppm after a period of 24 hr was found to be effective against Aedes aegypti larvae. Larval and pupal development was arrested resulting in decreased pupal transformation and adult emergence. Larval and pupal periods were prolonged with appearance of larval–pupal and pupal–adult intermediates, with an overall increase in the developmental period. Hatching was delayed and its rate was reduced compared to control. Disrupted egg shells and dechitinized body walls were observed, indicating clearly the anti-juvenile potential of the extract. The growth index was considerably reduced. These results suggest the leaf extracts of Abutilon indicum as a promising adult emergence inhibitor against vector mosquitoes and might be used in small volume aquatic habitats or breeding sites of limited size in and around human dwellings.

Morphological effects of some insect growth regulators on Musca domestica, (Diptera, Muscidae).

The current work was carried out to evaluate the morphological effects of insect growth regulators e.g. : applaud (buprofezin), consult (hexaflumuron) and match (lufenuron) as chitin synthesis inhibitors (CSIs), mimic (tebufenozide) as ecdysone agonist (EA) and admiral (pyripyroxyfen) as juvenile hormone analogue (JHA) against the housefly, M. domestica. Various morphological aberrations were induced in larvae, pupae and adults of M. domestica. The highest percentage of larval deformities caused by mimic, (can not molt or shrinked). Consult gave the highest percentage of malformation in the resulting pupae (C. shaped, elongated, distorted, two constricted, tapering anterior and broad posterior , cylindrical adult uncompleted). Admiral and mimic induced high percentage of abnormalities in the adult flies (small size body and curved legs, crumbled wings and curved abdomen). Larval-pupal intermediates and pupal-adult intermediates were induced as a result of these treatments.

Insect growth-regulating effects of Withania somnifera in a polyphagous pest, Spodoptera litura

Treatment of sixth instar larvae and pupae of the polyphagous pest Spodoptera litura Fabr. (Lepidoptera: Noctuidae) with an acetone extract of leaves of Ashwagandha, Withania somnifera L. (Solanaceae), caused toxicity, molt disturbances, formation of larval–pupal, pupal–adult intermediates and adultoids. Our results suggest that W. somnifera acts as an insect growth regulator causing disruption of the endocrine mechanism regulating molting and metamorphosis.

Anti-juvenile activity of Azadirachta indica extract on the development and morphometry of filaria vector, Culex quinquefasciatus (Diptera: Culicidae) Say

Efficacy of extracts of Ageratum conyzoides, Argemone mexicana, and Azadirachta indica were tested against Culex quinquefasciatus larvae. Petroleum ether extracts of A. conyzoides and A. mexicana with LC(50) values 425.60 and 267.90 ppm and 140.15 and 137.70 ppm after a period of 24 and 48 h, respectively, were found effective. However, the methanol extract of A. indica with LC(50) values 21.95 and 11.30 ppm after 24 and 48 h of exposure, respectively, was the most competent larvicide. The methanol extract of A. indica, being the most potent extract was therefore studied for its impact on the developmental scenario of the mosquito. It had a significant effect on the life cycle of the vector, C. quinquefasciatus. Hatching was delayed and its rate was reduced compared to control. Larval and pupal development was arrested resulting in decreased pupal transformation and adult emergence. Larval and pupal periods were prolonged with appearance of larval-pupal and pupal-adult intermediates, with an overall increase in the developmental period. Disrupted egg shells, dechitinized body walls, and distorted intestines were observed, indicating clearly the anti-juvenile potential of the extract. The growth index was considerably reduced.

Biocidal Activity of two botanical volatile oils against the larvae of Synthesiomyia nudiseta (Wulp) (Diptera: Muscidae)

The volatile oils of golden pillar, Cupressus macrocarpa and galangal, Alpinia officinarum were extracted and their constituents were identified. Alpha pinene and trans-caryophyllene were the major isolated constituents of C. macrocarpa oil, and 1,8 cineole and 4-terpeniol were the major compounds of A. officinarum oil. The present study revealed that the botanical volatile oils used, had morphogenic effects against S. nudiseta stages. Theseincludelarval-pupal intermediates, pupal-adult intermediates, deformed adults with crumpled wings and/ or deformed thorax and abdomen. Also some adults couldn't emerge and remained in their puparia. The histological effects induced by oils treatment in the body wall were represented by degeneration and detachment of hypodermis and dissolving of the exocuticle in some regions. The histopathological effects that appeared in the midgut were shrinkage in some epithelial cells and swelling of other cells.

Effect of sublethal concentrations of flufenoxuron on growth, development and reproductive performance of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Summary The effect of sublethal concentrations 0.00141%(LC20), 0.00251%(LC30) and 0.00336% (LC40) of a dispersible concentrated formulation of the insect growth regulator flufenoxuron (Cascade®), on larval growth and development, adult reproductive potential and egg hatchability of the red flour beetle, Tribolium castaneum, was investigated. When neonates were subjected to sublethal concentrations of flufenoxuron in artificial diet for 24 h, there were dose-dependent effects on larval weight, percent pupation and percent adult emergence, as well as time taken for adult emergence. A small proportion of larval-pupal as well as pupal-adult intermediates were observed at all concentrations. Adults emerging from the LC20 and LC30 concentrations laid mostly non-viable eggs, and the few larvae which emerged from viable eggs died at the first instar stage. At the LC40 concentration, all the adults that emerged were deformed and subsequently died. Flufenoxuron exhibited transovarial ovicidal activity resulting in the production of non-Viable eggs upon exposure of adults of different ages (2 days old, 3 days old and 4 days old) to treated diet. It was observed that in 2-day-old adults, fecundity decreased with an increased concentration. In the case of 3-day-old adults, there was no difference in fecundity with respect to the concentrations tested, although it was significantly less than the control. In the case of 4-day-old adults there was a drastic reduction in fecundity at LC40 and the eggs laid were abnormal at all concentrations. Topical application of sublethal concentrations of flufenoxuron to adults of either sex reduced the fecundity in a dose-dependent manner. Furthermore, the fecundity was reduced drastically in pairs where both the sexes were treated as compared to the pairs where only one sex was treated. Eggs showed a decrease in hatching percentage with increasing concentrations of flufenoxuron mixed with diet to which the eggs were exposed.

Larvicidal and chemosterilant activity of the acetone fraction of petroleum ether extract from Argemone mexicana L. seed

The acetone fraction of the petroleum ether extract of seeds from Argemone mexicana L. exhibited larvicidal and growth inhibiting activity against the second instar larvae of Aedes aegypti (Linn). This activity occurred at higher concentrations (200, 100, 50 and 25 ppm). Chemosterilant activity, including reduction in blood meal utilization (27.70%), reduction in fecundity (19.00%), formation of larval–pupal intermediates, formation of pupal–adult intermediates, adult mortality and sterility of first generation eggs (100%), occurred at low concentration (10 ppm).