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Effect of Neporex growth regulator on all phases of Anopheles stephensi

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The present study aimed to test the effectiveness of Neporex growth regulator against Anopheles stephensi, the results of the current study have shown the effect of Neporex on the phases of mosquito life, the mortality rate of eggs was 95.32% at the concentration of 2 gm/ L, while it reached 60.00% at the concentration of 0.5 gm/ L. The mortality ratio of larvae at the first phase was 100% at 2 gm/ L and 66.65% at 0.5 gm/ L after 120 h of treatment. The mortality ratio of nymphs was 70.01% at 2 gm/ L and 36.66% at 0.5 gm/ L after 72 h of treatment. In adults, the mortality ratio of male and female was 3.32% at 2 gm/ L after 168 h of treatment.
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Abdul-Razzaq et al (2019): Effect of Neporex December 2019 Vol. 22 (12)
©Annals of Tropical Medicine & Public Health S371
Effect of Neporex growth regulator on all phases of Anopheles stephensi
Hanadi A. Abdul-Razzaq1, Bafreen M. Raza1, Burhan M. Muhammad1
1. College of Science, University of Kirkuk, Iraq
*Corresponding author: nightsun882@yahoo.com (Abdul-Razzaq)
Abstract
The present study aimed to test the effectiveness of Neporex growth regulator against Anopheles stephensi, the
results of the current study have shown the effect of Neporex on the phases of mosquito life, the mortality rate of
eggs was 95.32% at the concentration of 2 gm/ L, while it reached 60.00% at the concentration of 0.5 gm/ L. The
mortality ratio of larvae at the first phase was 100% at 2 gm/ L and 66.65% at 0.5 gm/ L after 120 h of treatment.
The mortality ratio of nymphs was 70.01% at 2 gm/ L and 36.66% at 0.5 gm/ L after 72 h of treatment. In adults, the
mortality ratio of male and female was 3.32% at 2 gm/ L after 168 h of treatment.
Keywords: Neporex, Anopheles stephensi, mosquito life
How to cite this article: Abdul-Razzaq HA, Raza BM, Muhammad BM (2019):Effect of Neporex growth
regulator on all phases of Anopheles stephensi, Ann Trop Med & Public Health; 22(IV): S371. DOI:
O.2019.221225http://doi.org/10.36295/ASR
Introduction:
Anopheles, including the genus Anopheles stephensi, which belong to the Culicidae family are considered Diptera
vectors insects which cause some of serious and dangerous diseases which infect humans such as malaria, more than
300 million people are infected and one million deadin a year in the world, the control of the vectors is easier than
controlling the pathogen itself (Rajesh et al., 2014), Researchers have interested in vector mosquito control, and
chemical control has probably the most effectiveness in eradicating it, the damages which are caused by these
chemical eradications were not few, the use of these chemical eradications lead to the appearance of resistance
vectors, environmental pollution, high toxicity and high cost of chemical compounds for humans and animals, and
biological amplification (Khan et al., 2012). So many researchers turned to use insect growth regulators (IGRs),they
are chemical compounds used in the prevention of harmful insects, and this specificity has made them safe to use in
the environment,they do not affect humans, animals and fish (Stenersen, 2004). Mather and Lake (1982) noted that
the treatment mosquito larvae of Cx. salinarius and Ae. sollicitans at a concentration of 0.001 ppm from growth
regulator that MV 678 caused inhibition 100% of adult dysfunction of these two species. Awad and Mulla (1984)
found that the Cyromazine insect growth regulator caused many phenotypic abnormalities in mosquitoesof Cx
.quinquefasiatus when treating fourth stage larvae. Bell et al. (2010) also found that the Neporex growth regulator
inhibited the growth of eggs and adult domestic fly, Neporex growth regulator was also used against the
Galleriamellonella wax chloasma, which showed a clear effect on egg mortality ratios of 77% at 2 ml / L
concentration (Lahib and Thaer, 2017). The present study included knowledge of the effect of Neporex on the
different phases of Anopheles stephensi.
Materials and Methods:
1. The Collection and breeding of mosquito Anopheles stephensi:
The World Health Organization (WHO) method of breeding mosquitoes followed after sufficient numbers of adults
were collected by the Aspirator during March and April 2019 from Hawija district,it was placed in wide-mouthed
bottles covered with tulle cloth and taken to the laboratory, where it was released into her breeding cage and her life
cycle was followed up until the advent of the third generation. Adult slides were prepared for diagnosis according to
the taxonomic characteristics of taxonomic keys (Abul-Hab, 1968; Abdul-Qadir, 2000). For preparing sufficient
numbers of larval and nymph phases and adults, sufficient numbers of eggs were isolated to obtain the first larval
stage,while the second, third and fourth stage each of them prepared for the experiment by isolating sufficient
numbers of the larvae of the previous phase and placed in the individual breeding tubes and monitored until the
exuviation and arrival phase required for the experiment.
Abdul-Razzaq et al (2019): Effect of Neporex December 2019 Vol. 22 (12)
©Annals of Tropical Medicine & Public Health S371
2. Growth regulator (Neporex) Cyromazine:
It works to prevent metamorphosis uncompleted phases (larvae and nymphs) to adult insects from becoming
insects where they inhibit the synthesis of chitin and interfere with skin formation. It works by contact or by
digestive system and it is produced by Syngenta under the brand name Neporex at 50% concentration in the form of
wettable powder (WP), Different concentrations were prepared on the basis of the active substance Cyromazine and
the concentrations were (0.5, 1, 1.5, 2) gm/ L,this is according to (Mogregor and Karl, 1979) which depends on
dissolving each volume or weight of the pesticide in distilled water and completing the volume to a liter.
3. Bioassay to see the effect of Neporex growth regulator on the different roles of Anopheles stephensi:
3.1. Effect on eggs:
Pre-prepared concentrations were used and individual eggs were taken with 100 eggs per repeater using a soft
brush,placed separately in a 250 ml plastic container containing 100 ml of each growth regulator concentration s, the
eggs were sprinkled superficially with the same concentration in which they were placedby a hand sprayer with the
amount of 2 ml for each repeater from a height of 15 cm to ensure exposure of all eggs to the growth regulator.The
control treatment contains only sterile distilled water (Al-Issa, 1999). The eggs were monitored until hatching and
mortality was calculated (Ali, 2007), The mortality values were corrected according to the Orell and Schneider
equation (Shaaban and Al-Malah, 1993).
Whereas: C=ControlT=Treatment
3.2. Effect on the four larval stages:
Forty larvae were isolated from each of the four larval phases prepared as in paragraph (1), for each concentration
is distributed in four pots, three of them contains 100 ml of each concentration of growth regulator concentrations
and the fourth contains sterile distilled water only (control treatment), The treated larvae were transferred after 2
minutes by a soft brush to 250 ml glass jars containing sterile distilled water and add ed the larval food by 10 mg/
pot, it was deposited in the incubator at a temperature of 25 ± 2 °C and a light/ dark period of 14/10 hours (Al-Issa,
1999). The mortality rate was calculated daily for 5 days and the values were corrected as paragraph (3.1).
3.3. Influence in the phase of the Nymph:
The nymphs were isolated after anexuviation sufficient a number of fourth stage larvae and a similar number was
used in the larval phases, the same test method was applied in paragraph (2.3), the exception of not adding the bush,
with interest coverage of the pots in the tulle cloth in anticipation of the appearance of adults, the mortality rate was
calculated daily for 3 days, and the values were corrected as in paragraph (3.1).
3.4. Influence in adults:
Pre-prepared concentrations were used, sufficient numbers of nymphs were taken and individual placement was
placed in 1-liter tubes and closed with a cotton swab so metamorphosis them into adults Then, glass pickers were
prepared each with a capacity of 1 liter, inside each one of them saturated cotton with a sugar solution of
10%,placed in Petri dish a 9 cm dimeter, Each picker was sprayed with 5 ml of each growth regulator concentration
by a hand sprayer of approximately 15 cm height, while the control treatment was sprayed with sterile distilled
water, then transferred by aspirator 10 adult males and females newly emerging to the treated pickers, this
experiment was repeated three times for each concentration and the treated pickers were incubated in the conditions
referred to in paragraph 3.2 (Al-Rubaie, 2005), The mortality rate was calculated daily for 7 days and the mortality
values were corrected as per paragraph 3.1.
4. Statistical Analysis:
Data were analyzed according to Completely Randomized Design (C.R.D),the percentage of mortality was corrected
according to the Orell and Schneider equation (Shaaban and Al-Malah, 1993). Least Significant Difference (L.S.D)
at probability 0.05 was used to determine statistical differences between means of treatment (Al-Rawi and Khalfallh,
2000).
Abdul-Razzaq et al (2019): Effect of Neporex December 2019 Vol. 22 (12)
©Annals of Tropical Medicine & Public Health S371
Results and discussion:
The Effect of Neporex Growth Regulator on Different Roles of Mosquito Life An. Stephensi:
Effect of growth regulator on eggs:
The results from table (1) showed the effect of different concentrations of growth regulator on egg mortality, it was
confined between 60% and 95.32% at the concentrations 0.5 and 2 gm/ L, and statistical analysis confirmed the
differences in the results. Miura and Takashi (1979) noted that exposing Culex quinquefasciatus eggs to chitin
synthesis inhibitors SIR 8514 was reduced egg hatching to 40% in addition to abnormal deformity in hatching eggs;
it was the work of pesticides. Hijazi (2000) asserted that chitin synthesis inhibitors may inhibit chitin formation in
the fetus and die inside the egg shell as a complete larva, there are one of the most common symptoms resulting
from the superficial treatment of the egg. In other study Neporex growth regulator was used against domestic fly
eggs Muscadomestica the results showed the effect of growth regulator on the mortality rate of fly eggs it was
limited between 19.33% and 37% at concentrations 25 and 100 ppm (Al-Yasiri, 2014).
Table (1) Effect of Different Concentrations of Neporex Growth Regulator on Mosquito Eggs An. Stephensi
Conc. gm/ L
Mortality ratio of egg%
0.5
60.00
1
70.01
1.5
84.00
2
95.32
Control
0.00
* L.S.D value below 0.05 on the effect of concentration overlap on egg mortality ratios = 4.009
Effect of growth regulator on the four larval phases:
The table (2) shows the mortality ratio of the phases larval of mosquito An. Stephensi at different concentration of
the growth regulator Neporex and the exposure periods 24,72 and 120hours. Appears superiority the concentration 2
gm/L in achieving mortality ratios highest reach 76.67, 69.99, 62.23 and 53.33% for fourth phases larval
respectively. while the period 120 h achieving mortality ratios highest among the periods studied whereas reached
67.33, 62.662, 57.336 and 54.002% for fourth phases larval respectively. While for interaction between factors the
study were mortality ratios highest 100, 96.66, 90.01 and 86.66% at concentration 2 gm/ L and the period 120 h for
fourth phases larval respectively.
Table 2: Effect of different concentrations of Neporex growth regulator on the four larval phases of
mosquitoes An. Stephensi
Phase
Conc. gm/ L
Mortality ratio of larval phases% (hour)
Means of conc.
72
120
First
0.5
50.01
66.65
44.44
1
60.00
80
53.34
1.5
80.01
90
66.67
2
90.00
100
76.67
Control
0
0
0
Mean of periods
56.004
67.33
Second
0.5
40.01
63.33
38.89
1
50.00
70
46.67
1.5
70.01
83.32
60
2
80.00
96.66
69.99
Control
0
0
0
Mean of periods
48.004
62.662
Third
0.5
33.33
50.01
32.22
Abdul-Razzaq et al (2019): Effect of Neporex December 2019 Vol. 22 (12)
©Annals of Tropical Medicine & Public Health S371
1
43.33
66.66
42.21
1.5
20.01
60.01
80.00
53.34
2
70.01
90.01
62.23
Control
0
0
0
Mean of periods
41.336
57.336
Fourth
0.5
20.00
50.01
26.67
1
30.01
60.01
34.45
1.5
40.00
73.33
43.33
2
50.01
86.66
53.33
Control
0
0
0
Mean of periods
28.004
54.002
* L.S.D value (P≤ 0.05)for concentration= 3.25,periods= 3.996 and interaction= 4.009.
While were mortality ratios lowest 16.66, 13.33, 13.33 and 10.01% at the 0.5 gm/ L and 24 h for fourth phases larval
respectively. The mortality ratio was 0% when control treatment (Distilled water only). These results were
supported statistically by significant differences between treatments. Batera et al. (2005) founded when exposure the
third phase larvae of mosquitoes An. stephensi and Cx. quinquefasciatus of the Triflumuron growth regulator at a
concentration of 0.02 ppm lead to 100% destruction, He explained that the reason for the high mortality in the early
stages of larval phases that the growth regulator inhibited the Ecdysone hormone, which decreases efficiency with
the aging of larvae. Cetin et al. (2006) reported that Dimilin synthesis inhibitor lead to 100% Culex pipiens death
after 5 days, He explained that the cause for the destruction of the larvae in several days that the action of the growth
regulator is stronger whenever the longer time it passes to the larva exposure to him or to take it enough time to
reach the sensitive place in the insect tissue. Al-Yasiri (2014) noted that the Neporex growth regulator has an effect
on the larval mortality rate for the Musca domestica, as it mortality rate of the first phase larvae was ranged between
66.66% and 96.66% at 25 and 100 ppm concentrations after 120 hours of treatment.
Effect of growth regulator in nymph's phase:
The table (3) shows the nymph mortality ratio of the mosquito An. Stephensi at different concentration of the growth
regulator Neporex and the exposure periods 24, 48 and 72 hours. Appears superiority the concentration 2 gm/L in
achieving mortality ratio highest reach 51.12%, while the period 72 h achieving morta lity ratio highest among the
periods studied whereas reached 43.336%, while for interaction between factors the study achieved the
concentration 2 gm/ L after passed 72 h mortality ratio highest reached 70.01%, as recorded the concentration 0.5
gm/ L after 24 h mortality ratio lowest reached 16.66%. This indicates that there is a positive relation between the
mortality rates and the concentrations used by the growth regulator and the results were based on statistical analysis.
Hall and Foehse (1980) founded that the treatment of the nymphs of the fly Musca autumnalis inhibitors of the
formation of chitin CGA - 72662 at a concentration of 50µgm/ L lead to their death 100%,he added that the lack of
emergence of adult nymphs treatment inhibitor chitin synthesis referred to may be due to the sensitivity of the phase
of the nymph because of the incomplete hardening of her body wall if treated at the age of one day, this leads to the
penetration of large quantities of the regulator inside it affects its development Thus, it does not complete the nymph
phase or it completes its development and comes out partially as parts of its body stick to the nymph wall. Al-Yasiri
(2014) also founded that the Neporex growth regulator had an effect on the mortality rate of Musca
domesticanymphets, which was between 30% and 73.33% at concentrations 25 and 100 ppm respectively after 72
hours of treatment.
Table (3) Effect of Different Concentrations of Neporex Growth Regulator on Mosquito Nymphs An. Stephensi
Conc. mg/ L
Mortality ratio of nymphs% (hour)
Means of
conc.
24
48
72
0.5
16.66
23.32
36.66
25.55
1
16.66
33.33
50.01
33.33
1.5
23.33
40.01
60.00
41.11
2
30.01
53.33
70.01
51.12
Control
0
0
0
0
Mean of periods
17.332
29.998
43.336
* L.S.D value (P≤ 0.05) for concentrations= 3.25, periods= 3.996 and interactions = 3.31.
Effect of growth regulator in adult's phase:
Abdul-Razzaq et al (2019): Effect of Neporex December 2019 Vol. 22 (12)
©Annals of Tropical Medicine & Public Health S371
Table (4) shows that there is no effect of different concentrations of Neporex regulator in mosquito adults An.
Stephensi, whereat is highest mortality rate was 3.32% for males and females at 2 gm/ L concentration after 168
hours, the results also showed no significant differences between treatments. Al-Issa (1999) noted that insect growth
regulators are changing the structural construction of the body's wall and decreasing its functional activities, whereat
reduces the insect's ability to walk and fly further to their effect on the maturation and development of the ovaries
and then the production of unfertilized eggs, this is congruent with what Da-Sliva et al.(2004) that the adults ofAn.
stephensi and Cx. quinquefasciatus does not die when it is exposed to the inhibitor of the formation of chitin
Triflumuron but there is a lack of functional activities and lack of nutrition thus reducing the number of laideggs by
treatedfemales. Al-Yasiri (2014) also showed no effect of different concentrations of Neporex growth regulator in
adult fly Musca domestica, whereat the highest mortality rate is was 6.66% for males and 13.33% for females at 100
ppm concentration after 168 hours.
Table (4) Effect of Different Concentrations of Neporex Growth Regulator on Adult Mosquito An. Stephensi
Conc. mg/ L
Mortality ratio of adults% (hour)
24
72
120
168
Male
Female
Male
Female
Male
Female
Male
Female
0.5
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.5
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2
0.00
0.00
0.00
0.00
0.00
0.00
3.32
3.32
Control
0
0
0
0
0
0
0
0
* L.S.D value (P≤ 0.05)for interactions =0.00.
We conclude that the NEPOREX growth regulator had considered effective in controlling An. stephensi, and the
efficiency of this preparation reached its peak at high concentration 2 gm/ L and long periods of exposure under the
study, and the best time for use is in the egg stage and the firstly phases larval because it's highly sensitively, thus
recommend that using this insecticide of environmentally safety in controlling when the first growth stages of the
best results.
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When eggs of Culex quinquefasciatus Say were exposed to water treated with SIR 8514 (2-Chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide] abnormal hatching (longitudinal split of shell or partial hatching) as well as ovicidal activity resulted; younger embryos (0.5–4.5h) were the most sensitive and older embryos (23.5 h) were tolerant. Abnormal hatching and ovicidal activity also were produced by baiting adults with SIR 8514 in sucrose. The compound showed no effect on egg hatchability when applied as a contact film to adult mosquitoes.
Article
The insect growth regulator cyromazine [Larvadex (N-cyclopropyl-l,3,5-triazine-2,4,6-triamine)] induced various morphogenetic aberrations in the mosquito Culex quinquefasciatus after treatment of 4th-instar larvae. Most of the treated larvae died as pupae, exhibiting various degrees of morphogenetic aberrations. The most characteristic aberration was the formation of a transparent anterodorsal thoracic bulbous projection followed by dorsal splitting of the thoracic cuticle of the prepupa. Albino pupae and distended pupae were also noted. At a marginal lethal concentration most of the morphogenetic effects occurred in the adult stage, while at higher concentrations most occurred in the pupal stage. There was a direct relationship between concentration and the magnitude and frequency of morphogenetic aberrations. Histological examinations revealed no noticeable effects in any tissue of treated larvae.