Effects Of Cantharidin On Life History Traits Biology Essay

The sub-lethal toxicological effects of cantharidin were tested to measure its toxicity to Helicoverpa armigera Hub. ( Lepidoptera: Noctuidae ) . The aims of our surveies were to determine the long term chronic effects of cantharidin on the population kineticss of H. armigea under research lab conditions. The informations were analyzed by TWOSEX life tabular array package. Our consequences showed gross abnormalcies in population parametric quantities of H. armigera, runing from larvae to grownups. Decrease in larval weight and wings deformity was observed in treated population cohort. Relatively, higher mortality at larval, pupal and big phases was recorded in treated, compared to untreated. Almost five times less fruitfulness was recorded in treated population cohort. Birthrate was besides badly affected. In short, decrease in all population parametric quantities was registered. It is beyond the range of our research to conceive of the consequence of cantharidin in the field populations of the plague. However, usage of cantharidin in the field could besides do serious abnormalcies in H. armigera population parametric quantities and may hold deductions for pest direction determination doing procedure. More interestingly our experiment revealed that cantharidin in sub-lethal dosage mimicked IGRs insect powders.

Introduction

American bollworm, Helicoverpa armigera Hubner, Lepidoptera ; Noctuidae is considered one of the major plague of cotton, leguminous plants and more than hundred other works species ( Bhatnagar et al. , 1982 ) . Helicoverpa armigera is a widely distributed plague and its presence has been recorded in Asia, Europe, Australia and Africa ( EPPO, 2006 ) . Global output loss from this plague is amounting to US $ 2 one million millions yearly ( ICRISAT, 2003 )

The indiscriminate usage of insect powders, peculiarly during 80s and 90s contributed to the outgrowth of the cotton bollworm, Helicoverpa armigera as a primary plague of cotton, in recent old ages. Control of this plague was non ever adequate likely due to the development of opposition. Moderate to high degree of opposition to pyrethroides and organophosphorus insect powders were recorded in field population of H. armigera ( Ahmed et al. , 1995 ) .

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Biopesticides with manner of action other than the conventional insect powders may cut down the hazard of insecticide opposition and pest revival jobs while relatively safe and ecologically acceptable. In early surveies, our campaigner insect powder, cantharindin EC pesticide had been found to hold low toxicity against quail, ladybird beetles and dirt micro-organisms by ( Feng-Li et al. , 2009 ) while analyzing on its safety rating against non-target beings.

The insecticidal and anti-feedant activities of cantharidin are good established fact as elucidated by ( Yalin et al. , 2003 ) on army worm and diamond moth. However, its sub-lethal toxicity on population parametric quantity has non yet been studied. Here we put emphasis on sub-lethal toxicity of cantharidin as it is of great significance in footings of low mammalian toxicity.

The chief intent of this survey was to determine and research the consequence of cantharidin on development, fruitfulness, birthrate and other ecological parametric quantities of H. armigera Hub. by cantharidin incorporated diet, in the research lab.

Materials and Methods:

Cantharidin extraction and purification:

Cantharidin was extracted and purified in the “ Key research lab of works protection resources and pest direction, Ministry of Education, Yangling 712100, Shaanxi Province, Northwest A & A ; F University ” from meloide beetles, commercially procured, utilizing standard research lab protocol.

Insects raising:

Helicoverpa armigera larvae procured from Henan Jiyuan Baiyun Industry Co. , Ltd. China and reared until F1 for usage in bio-assay. Group of 24 larvae were placed into 24 chamber plastic box obtained from the company. The boxes were placed in an brooder at 22A±2a-‹C and 40A±5 % RH with 12 hrs photoperiod. After pupation pupae were collected and placed in plastic jar holding cotton fabric on both sides and phial was placed in the center with 10 % sugar solution dispensed through cotton. Eggs were collected on the lower and upper cotton fabric and placed in crystalline plastic bags for outgrowth.

Artificial diet:

Cotton bollworms were reared in the research lab on modified semi-synthetic diet ( Ahmed and McCaffery,1991 ) , dwelling of Chickpea flour, Sorbic acid, Wesson ‘s salt, Vitamin ( ABDEC ) , Ascorbic acid, Yeast ( Brewer ‘s ) , Choline chloride, Agar agar, methanal, streptomycin sulfate and methyl-p-hydroxy benzoate, under laboratory status of 22A±2A°C, 40A±5 % RH and 12:12 hour Light: Dark. A homogenous stock of 3rd instar larvae was obtained for several bio-assay and initiation interventions

Bioassay and computation of Lethal clip ( LT50 ) :

Third instar larvae of H. armigera were used to find deadly clip, LT50. Healthy insects were introduced to unreal diet treated with 0.5mg g-1 cantharidin. Datas were recorded after 12, 24, 48, 72 and 96 hour after intervention. Datas were subjected to probit analysis for computation of LT50 ( Finney, 1971 ) .

Initiation intervention:

Cantharidin used in our surveies was extracted in the research lab as mentioned above. Third instar larvae, being more robust were selected for this survey. Insects were unbroken hungry for 8 hours before their debut to cantharidin ‘s treated diet. Insects were introduced to diet incorporating 0.05 mg g-1 of cantharidin for three yearss. Afterwards, larvae were provided with untreated unreal diet.

Development of life table informations:

Two cohorts of Helicoverpa armigera foremost instar larvae were indiscriminately selected from research lab settlement and placed separately in 24 cells insect civilization racks until 3rd instar. Third instar larvae in control group were fed unreal diet with propanone and larvae in intervention group were fed with 0.05mg g-1 cantharidin treated unreal diet until 72 hours and replaced with unreal diet without cantharidin until pupation.

Developmental times, age-stage specific endurance rates ( sij ) , age phase specific fruitfulness ( fij ) , age specific endurance rate ( sixty ) , where ten is the age and J is the phase, and age-specific fruitfulness ( maxwell ) were recorded daily until the decease of all persons. After grownup outgrowth, females and males were paired and placed in fictile container of 0.5 litre capacity with cotton fabric for oviposition and on the palpebra to better airing and were fed 10 % honey solution in H2O. Age-stage, two-sex life tabular arraies were constructed following ( Chi, 1988 ) . Percent birthrate was calculated as: ( eggs hatched ? eggs laid ) x 100. Effective fruitfulness was calculated as eggs laid female-1.

Statistical analysis and population parametric quantities:

Fecundity and birthrate informations from the female for each population cohort were subjected to independent sample t-test utilizing SPSS-17 ( SPSS Inc. , 2007 ) . Confidence degree of Pa‰¤0.05 was considered important.

Population parametric quantities of each cohort were calculated by:

( 1 )

( 2 )

( 3 )

The age-stage life anticipation ( eij ) was calculated harmonizing to Chi and Su ( 2006 ) . The intrinsic rate of addition was estimated by utilizing the iterative bisection method from Euler-Lotka equation ( Eq. 1 ) with age indexed from 0 ( Goodman, 1982 ) . The ocular BASIC based TWOSEX life tabular array computing machine package was used to cipher these parametric quantities ( Chi, 2008 ) . This package besides includes map for the appraisal of standard mistake of population parametric quantities utilizing Jackknife technique ( Meyer et al. , 1986 ) . Data obtained as end product text format were exported to MS Excel ( Microsoft, 2003 ) . Differences in life history traits and population parametric quantities between H. armigera treated and untreated to cantharidin were compared by t-tests ( Zar, 1996 ) .

Consequences:

Bioassay consequences showed profound toxicity of cantharidin on 3rd instar larvae of H. armigera ( Fig. 1 ) . Deadly clip LT50 and LT90 were found to be 26.62 and 44.98 hour, severally.

Cantharidin showed short-run every bit good as long term effects on H. armigera different life phases. Short-run effects include reduced larval size, anorexia, whereas long term effects include pupal, moth deformity every bit good as reduced pupal weight and moth size. Development clip for larvae to pupae in cantharidin treated cohort population was longer as compared to untreated control.

Negative consequence of cantharidin can besides be seen in age phase survival rate curves ( Fig. 2 ) . High mortality at larval phase was observed in cantharidin treated cohort population as compared to untreated control. Pupal mortality was besides observed in cantharidin treated cohort, whereas no mortality was observed in untreated control. Consequently, lower endurance curves at larval, pupal and big phases were obtained. Severe negative impact of cantharidin was observed on larval and pupal phase. The age phase specific life anticipation in cantharidin treated cohort was shorter for larvae and pupae every bit compared to untreated control cohort ( Fig. 3. ) . Age specific endurance rate showed measure wise decrease form in cantharidin treated cohort as compared to untreated control cohort ( Fig. 4 ) . Age specific mortality can be seen more marked in cantharidin treated as compared to untreated control ( Fig. 5 ) . Sing birthrate of cohort, cantharidin negatively affected on reproduction was obvious in age specific cohort fruitfulness ( Fig. 6 ) . Reduced larval and pupal weights were obtained in cantharidin treated in comparing with untreated ( Fig. 7, 8 ) . In our experiment more or less decrease was seen in all population parametric quantities ( Table 1 ) . The intrinsic rate of addition ( R ) and net reproductive rate ( R0 ) of cantharidin treated cohort was 0.09 and 1.09, whereas 0.13 and 1.14 in untreated control, severally. Table 2 shows increased larval and decreased grownup continuance in cantharidin treated cohort. Average coevals clip remained 40.36 and 38.97 in treated and untreated, severally. Fecundity, birthrate and effectual birthrate in cantharidin treated cohort remained 134.2, 13.12 and 125, whereas 364.20, 87.75 and 376.04, severally. All the parametric quantities remained significantly different at Pa‰¤0.05 ( Table 3 ) .

Discussion:

In present surveies cantharidin was found to hold strong insecticidal activities. Like wise, the insecticidal and anti-feedant activities of cantharidin as good established fact was elucidated by ( Yalin et al. , 2003 ) on army worm and diamond moth. However, its sub-lethal effects on population parametric quantities have non been studied so far. Sub-lethal toxicity is of great practical importance from the direction every bit good as ecological point of position.

Earlier surveies showed that the toxicity of cantharidin has been its binding to phosphoprotein 2A ( PP2A ) . Other than PP2A elaborate physiological and biochemical effects of cantharidin and its mechanism of action remains widely unknown ( Graziano and Casida, 1987 ; Kawamura et Al, 1990 ; Graziano et Al, 1987 ; Decker 1968 ; Bagatell et Al, 1969 ) . In our experiment cantharidin intervention of sub-lethal dosage significantly reduced all population parametric quantities.

Cantharidin in our survey caused decrease in larval weight. Decrease in larval weight could be because of the reduced degree of enzymes activity and indicated general perturbation in metamorphosis, in cantharidin treated insects. Other relevant surveies suggested that reduced degree of digestive enzymes suggests reduced P release for energy metamorphosis, reduced rate of metamorphosis, every bit good as reduced rate of metabolites and could be the direct consequence of cantharidin on enzyme ordinance ( Huang et al, 2004 ; Nathan et Al, 2005 ) . Furthermore, crippled wing of both male and female were observed in cantharidin treated cohort population. This could do flight break and copulating under field conditions and accordingly do them apt to be an easy quarry and accordingly decrease in field population could be achieved. As a affair of fact, all these morphological traits have profound consequence on fittingness of population under field conditions. Decreasing population growing curves indicates the profound decrease in Forth coming coevals population. In old surveies, Sharma et al. , 2006 reported similar symptoms by handling H. armigera larvae with azadirachtin-A and tetrahydroazadirachtin-A dressed ores that caused growing suppression, deformity and mortality in a dose-dependent mode.

Typically, natural mortality between 1 % and 15 % is regarded normal during immature phase ( at foremost larval instar, by and large ) , because this phase is the most sensitive one ( Carvalho et al. , 1998 ) . However, mortality recorded at subsequently larval and pupal phase in cantharidin treated population cohort could be related to chronic effects of cantharidin.

Another damaging consequence of cantharidin was seen on fruitfulness and birthrate of H. armigera. In our surveies both the egg figure and continuance of oviposition was reduced as it is of import to take into history the relevancy of oviposition of female in finding the future population growing ( Lewontin, 1965 ) .

In visible radiation of the above surveies we may reason that cantharidin has deep profound effects on all population parametric quantities. Amongst all the population parametric quantities effected, birthrate was worst effected. Interestingly, cantharidin mimicked IGRs in sub-lethal doses. In short, more research is needed to research the mechanism and potency of cantharidin and its parallels for future pest direction.

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