COMPARATIVE STUDY OF THE COWPEA BEETLE, Callosobrochus chinensis (L.) RESISTANCE TO MALATHION AND PYRIPROXYFEN

COMPARATIVE STUDY OF THE COWPEA BEETLE, Callosobrochus chinensis (L.) RESISTANCE TO MALATHION AND PYRIPROXYFEN

A. M. Shams El-Dine ^*;  W. M. H. Desuky**; R.E.M.Omar^*; Asmaa M. M.  Muhamed^**

*Plant Protection Department, Faculty of Agriculture, Benha University, Egypt.

** Plant Protection Research Institute, A.R. C., Dokki, Giza, Egypt

ABSTRACT

Development of resistance to malathion and  pyriproxyfen  in  population of cowpea  beetle,  Callosobrochus chinensis (L.) was evaluated under laboratory condition during twenty successive generations. Data cleared that the resistance ratio with    malathion  selection was  fewer  than   pyriproxyfen,  the  resistance ratios  were  11.54   and  -131.25  fold,  respectively  after  twenty  successive generations. The resistance ratio was increased slowly in malathion population and became resistant after twenty selected generations, while with pyriproxyfen, the population became   resistant after only ten generations. Development of resistance in pyriproxyfen populations was faster than malathion population. These results show that malathion is more active than pyriproxyfen in cowpea beetle control.

Keywords: Development of resistance,C. chinensis, malathion, pyriproxyfen , generations.

INTRODUCTION

Cowpea beetle, Callosobrochus chinensis (L.)  considered a serious  pest on stored products. So, it was controlled by many conventional    pesticides, such as carbaryl and malathion (Gouhar et al., 1980). The   intensive  use of pesticides against this pest led to increase of level of resistance to many pesticides. So, alternative agents were  used  to control  this pest called no conventional agents such  as insect growth regulators (IGRs). Pyriproxyfen is one of the most active compounds against many  pests used in this  experiment. This compound   belongs   to juvenile hormone mimics and is considered a leader compound for controlling white flies (Ishaaya et al.,1994). In this work comparison between malathion   resistance (conventional pesticide) and pyriproxyfen resistance (non conventional   pesticide) was carried out. Unfortunately, there is no data in the literature on   the development of resistance to pyriproxyfen with cowpea beetle. Pyriproxyfen affecting in the hormonal balance and in some cases suppression of embryogenesis, metamorphosis and adult formation (Aamirand ElFishawy, 1987) and (Koehler and Patterson, 1991).On the other hand, Haubruge and Arnaud (2001) recorded that developed specific resistance in Tribolium   castenium to malathion.

Therefore, this study focused on the comparison between the development of resistance in C. chinensis to malathion and pyriproxyfen during twenty successive generations.

 MATERIALS AND METHODS

 1- Tested insects:

             The    original    population of the cowpea beetle, Callosobrochus  chinensis  (L.)  which  used in this  study  consists of 1000   adults, were   collected   from  the  infested cowpea  seeds stored in  local  warehouses  in  Zagazig  region.  The collected insects were mixed and reared in laboratory conditions (30 ± 1C˚ and 70 ± 5 % R.H.). Cowpea seeds were used as a rearing host. Fresh cowpea seeds  were   firstly  examined to  insure that it is in a good case, then  it  was packaged  in  plastic  bags,   tied  with  thread and kept at 20 C˚  in a deep-freezer for one week at least    to  kill   any  internal infestation.  The first generation of the collected insects introduced into 2kg glass jars, half filled with sterilized cowpea seeds, variety Karem 7. The jars were covered with  muslin cloth secured by rubber bands and kept  in an incubation adjusted  at 30 ± 1C˚ and 70 ± 5 % RH. when the adults started  to   emerge, the newly emerged  ones (0-24 hours old) were used in the experiment. The adults were confined with sterilized cowpea seed in five pound glass jars for six hours, and then were transferred. The infested seeds cultures are prepared to expose to selection   pressure with   the   pesticides used during successive generations.

2- Tested pesticides:

A - Malathion

Trade name: Malathion  57 %

Common  name: Prentox

Basic product: BASF-Helena Company.

B - Pyriproxyfen

Trade Name : Admiral

Common name: Pyriproxyfen

Basic product: Sumitomo Company.

3-Determination of resistance of the cowpea beetle to the tested pesticides:

            The infested seeds   were divided   to three batches, the first was sprayed by Malathion after 24 h. of laying and the second batch was sprayed with Pyriproxyfen after 24 h. of laying while, the third one was sprayed with acetone pure after 24 h. of laying. Both insecticides and juvenile hormone, mimic were dissolved in acetone unless otherwise indicated in the text. Most of the experiments were carried out using five concentrations and twenty gm. of seeds were used for each concentration. It was found that 2ml of acetone was completely enough to cover this amount of seeds. After spraying, the seeds were allowed to dry air, and then transferred to plastic container until hatching. Control eggs received either pure acetone. Each experiment contained four replicates, 25 seeds were used for each. Unhatchability percentages were assessed after 7 days and corrected according to Abbott's formula (1925). The regression lines were plotted on computer propane this method was carried out during 20 generations and the resistance ratios were calculated by dividing the LC₅₀ values of the resistance strain on the LC₅₀ values of the parent (susceptible strain).  

 RESULTS AND DISCUSSIONS

1- Development of   resistance of   the cowpea beetle to Malathion: 

            The strain of  the cowpea beetle, Callosobrochus  chinensis  (L.) selected  with  malathion did not develop a high degree of resistance in spite of the successive direct exposure of eggs to selection pressure by successive concenterations of malathion (every generation). Insecticidal selection was contenued up to twenty generations at the selection pressure of mortality of adults. The obtained resultes are presentd in Table 1 and Figure 1. The dosage mortality response of C. chinensis (selected strain) to malathion selection pressure was relatevily slow during the whole period of selection.The LC₅₀ values increased gradually from (29.11) ppm in the parent generation to (225.10) ppm in F20. The strain became ressistance in F20, the fold of resistance 11.54- Fold. Figure 1 show that the fold of resistance increase gradually and there are no fluctuation, this mean that the malathion-resistant strain was homogensous. The slope value also increase gradually from 2.76 ± 0.22 in the parent to 4.35 ± 0.44. The highest increasing in the resistance  ratio was observed between F10 and F15 as mentioned in Table 1 and Figure 1. Resistance factor at level of LC₅₀ indicated that the rate of resistance developement to malathion was ingraduall and slow untill F20 (11.54 – fold ) of this generation.

  Development of resistance to malathion in most insect species of stored products was extensively studied whether in laboratory or in natural stores and many reports from different parts of the world were recorded. Kaiyoku and Tsukuda (1964) reported that resistance to malathion, DDT and Fenitrothion in C. chinensis as a result of laboratory selection pressure was increased to malathion but decreased to the other two insecticides, these changes in susceptibility of insects were attributed to ecological adaptation to insecticides. Zettler (1974), found that resistance ratio in T. castaneum, which

Table 1.  Development of resistance in the cowpea beetle, C. chinensis  eggs to malathion during 20 successive generations.

was collected from stored peanut in Georgia, to malathion ranged from  9.60  to 108.70   fold  at LD₅₀ level. The present results are in agreement with those obtained by Aamir (1975) stated that dvelopment of resistance to malathion in the cowpea beetle, C. maculatus was very low and weak reaching to 2.47 fold only in F19 in spite of the successive selection pressure (every generation) of adults at the concentration that kill 50-60 % of adults and the resistance factor was 0.33 - fold  at LC₉₀ level. Zettler and Arthur (1997), stated that strains of T. castanium and T. confusum collected from flour were resistant to malathion and dichlorfos  and T. castanum were more resistant than T. confusum.

2- Development of   resistance of   the cowpea beetle to pyriproxyfen:

The selection was thus continued for 20 successive generations and the level of resistance was measured every 5 generations. Results obtained are presented in Table 2 and Figure 2. Data show that the cowpea beetle eggs developed sharp increase in resistance to pyriproxyfen during 20th successive generations. The LC₅₀ values of the selected strain increased gradually as a result of selection. The rates of increasing were not sharp in the parent and F5; the folds of resistance were 0.17 and 0.16, respectively, then markedly increased to 23.55 and 122.33 fold in F15 and 131.25 fold in F20, respectively. The slope values were fluctuated from generation to other, the values were 0.51 ± 0.05, 0.47 ± 0.05, 2.37 ± 0.02, 3.00 ± 0.27, 2.47 ± 0.26 in F0, F5, F10, F15 and F20, respectively. Data confirmed that the   development of  resistance to pyriproxyfen in the tested insect (eggs) was very rapidly from F10 to F15.

          The fluctuation in slope values indicate that the strain become heterogeneous (Table 2). The efficiency of pyriproxyfen against many species of insects was extensively studied by many investigators, but the literature about the development of resistance in insects against these J. H .mimic pyriproxyfen is very rare. The potential resistance in cowpea beetle to pyriproxyfen was developed rare rapidly in spite of the exposure of eggs for 2^nd successive generation to selection pressure at the concentrations. Findings confirmed the results of Elbert and Nauen (2000), who reported that development of resistance in Bemesia tabaci more rapidly, has developed high degree of resistance against several chemical classes of insecticides, including organophosphates and/or insect growth regulators. Horowitz et al. (2002) also found that dynamic of pyriproxyfen resistance in B. tabaci have been studied intensively in cotton field and green houses in Israel. High resistance to pyriproxyfen evolved one year after its introduction for use one flower. In green houses ,a high level of resistance was observed after ten rears .But its rate of development different among localities due to the absence of applications of pyriproxyfen in some cotton fields. Horowitz andIshaaya (1995)   collected  white  flies from  three   green   houses   and   exposed

Table 2.  Development of resistance in the cowpea beetle C. chinensis to   pyriproxyfen during 20 successive generations.

 them to a series of conc. Insect growth regulators, buprofezin and pyriproxyfen assays. They indicated an-4-fold increase intolerance to buprofezin after 2 successive applications of that relatively high level of resistance to pyriproxyfen, after 3 successive applications of that compound at the LC50, the resistance ratio value for suppression of egg-hatch was 554-fold adult emergence failure. Li et al. (1997) reported that musca domestica strain highly resistant to pyriproxyfen, a Juvenil hormone analogue, was established by laboratory selection for flies. The strain developed  4900 - fold   to pyriproxyfen in the 3^rd instars larvae by the 17^th generation of selection from a level of only 3-8 fold before selections (compared to susceptible strains ). Bioassays of synergism showed that the resistance ratio white pupae of M. domistica were depressed to 29 fold from 400 fold by acytochrome P450 inhibitor. These results indicate that P450 monooxygenase plays an important role in M. domistica resistance to pyriproxyfen. The present results are in agreement with those obtained by Aamir (1981) and Aamir & EL-Fishawy (1987) as discussed before in case of Malathion. To throw some light in the difference between malathion and pyriproxyfen in the rate of resistance (131.25-fold for pyriproxyfen and 11.54-fold for malathion). This means that, the cowpea beetle acquired resistance quickly against pyriproxyfen compared to malathion. Although, this pest acquired resistance to pyriproxyfen quickly, the parent generation in malathion selected strain was more resistance than the parent generation in pyriproxyfen (the LC50 for malathion parent was 29.15 ppm, while, in pyeiproxyfen was 0.04 ppm).The slope values in malathion selected strain was increased gradually, while, in pyriproxyfen selected strain the slope values were fluctuated from generation to another this mean that the malathion –selected strain was homogenous , on the other hand the pyriproxyfen – selected was heterogeneous as mentioned at in Table 3 and Figure 3.

In  conclusion:

         From these results, it could be concluded that

REFERENCES

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Aamir, M. M. I.   (1981): Study toxicologic   asupra  raselor  de Tribolium  confusum rezistante  la  insecticidele de  contact . Ph D. Thesis, Faculty of Agriculture,  IANB - Bucharest ).

Aamir   M. M. I.  and A. A.  El Fishawy (1987):  The effect of selection  with  deltamethrin on  biology  of  Callosobruchus maculatus (F.).  Bull.  Ent. Society,  Egypt,  Econ. Ser., 16: 11-19.

Abbott, W. S. (1925): A method of computing the effectiveness of an insecticide. Journal of  Econ.  Entomol., 18: 256-269.

Elbert, A. and R. Nauen (2000): Resistance of Bemisia tabaci (Homoptera: Aleyrodidae) to insecticides in southern Spain with special reference to neonicotinoids. Pest-Management Science, 56 (1): 60-64.

Gouhar,  K. A.; M. M.  Mansour; M.  W.  Guirguis  and  M . I. Amir (1980):  Development of  resistance   to   carbaryl,    malathion    and   Lindane in a strain of Callosobruchus maculatus  (Fab.). Bull.  Ent. Society, Egypt, 12: 5 - 10 .

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دراسة مقارنة بین مقاومة  حشرة  خنفساء  اللوبیا لکل  من  مبیدی 

الملاثیون  والبیروبروکسیفین

علی محمد شمس الدین¹ ، وحید محمود حسین دسوقی²، رضا السید محمد عمر، أسماء مغاوری محمد محمد

1. قسم وقایة النبات- کلیة الزراعة بمشتهر- جامعة بنها- بنها- مصر.
2. معهد بحوث و قایة النباتات- مرکز البحوث الزراعیة- دقی – جیزة- مصر.

 الهدف الرئیسی لهذه الدراسة هو معرفـة  قدرة  حشرة خنفساء اللوبیا علی  اکـتساب مقاومـة لأحد  منظمات  النمو  الحشریة  عندما  یستخدم   هذا  المبید  فی  مکافحة    الحـشرات    فترات   طویلة،    وذلک    بالمقارنة  بأحد  المبیدات الفسفوریة المعروفة  وهـو  مبید الملاثیون   و الذی  یستخـــدم  فی مکافحة   حشرات   المخازن علی نطاق  واسع . ولقد تم تقییم  تطور مقاومة حشرة خنفساء اللوبیا    لکل من  الملاثیون  و البیروبروکسیفـین  تحت الظروف المعملیة وذلک  خلال  عشرین  جیلا   وقد  أظهرت النتائج أن مستوى مقاومة الحشرة للملاثیون  کان أقـل بکثیر من المقاومة للبیروبروکسیفـین حیث کانت نسبة المقاومة    11.54  ،  131.25   ضعف  على التوالی. فی حالة الملاثیون معدل المقاومة زاد زیادة بطیئة وتدریجیة  حیث    ظهرت  المقاومة    فی    الجـیل العشریـن تقریبا ، بینما فی  حالة البیروبروکسیفـین ظهرت المقاومة أسرع  حیث ظهرت  فی   الجـیل   العاشر وهذا یعنى أن مقاومة خنفساء اللوبیا للبیروبروکسیفـین یتطور بصورة أسرع  فی مقاومتها للملاثیون ومن  هنا فهذه النتائج تؤکد أن فاعلیة الملاثیون على هذه الحشرة أکبر عن فاعلیة البیروبروکسیفـین.