El_Baradey, W., Refaei, E., Amer, M. (2023). Influence of Various Ecological Factors on Population Fluctuations of Icerya Seychellarum (Westwood) Infesting Guava Orchard in El-Behara Governorate.. Journal of the Advances in Agricultural Researches, 28(4), 795-802. doi: 10.21608/jalexu.2023.243472.1161

wafaa M. M. El_Baradey; Elsayed A. Refaei; Marwa E. S. Amer. "Influence of Various Ecological Factors on Population Fluctuations of Icerya Seychellarum (Westwood) Infesting Guava Orchard in El-Behara Governorate.". Journal of the Advances in Agricultural Researches, 28, 4, 2023, 795-802. doi: 10.21608/jalexu.2023.243472.1161

El_Baradey, W., Refaei, E., Amer, M. (2023). 'Influence of Various Ecological Factors on Population Fluctuations of Icerya Seychellarum (Westwood) Infesting Guava Orchard in El-Behara Governorate.', Journal of the Advances in Agricultural Researches, 28(4), pp. 795-802. doi: 10.21608/jalexu.2023.243472.1161

El_Baradey, W., Refaei, E., Amer, M. Influence of Various Ecological Factors on Population Fluctuations of Icerya Seychellarum (Westwood) Infesting Guava Orchard in El-Behara Governorate.. Journal of the Advances in Agricultural Researches, 2023; 28(4): 795-802. doi: 10.21608/jalexu.2023.243472.1161

Influence of Various Ecological Factors on Population Fluctuations of Icerya Seychellarum (Westwood) Infesting Guava Orchard in El-Behara Governorate.

^{1}Plant Protection Research Institute, Agricultural Research Center, Giza, Egypt

^{2}Plant Protection Research Institute (PPRI), Agricultural Research Center (ARC), Egypt

Abstract

Icerya seychellarum (Westwood) (Homoptera: Monophelibidae) is the most important mealybug species in Egypt which attacking guava orchards. The purpose of this study was to observe the fluctuations in population of this insect pest in guava orchards throughout two seasons of 2020/ 2021 and 2021/ 2022 in Rashed region, El-Behara governorate. The obtained results indicated that, I. seychellarum had 2-3 peaks of population density during the first and second years of the study. There was a good synchronization between nymphal population of I. seychellarum and populations of the two predators Rodalia cardinalis (Mulsant) (r= 0.69 and0.78) and Chrysoperla carnea (Stephens) (r = 0.63 and 0.61) during the previous period. The impact of weather factors (temperature and relative humidity) on population of I. seychellarum and the associated predators (R. cardinalis and C. carnea) were examined.

There were various mealybugs species (Hemiptera: Margarodidae) were attacking the guava trees (Psidium gaujava L.) in Egypt, and the infestation by these species eventually causes losses in the crop's quantity and quality, (Sayed, 2008; Attia, 2010; Awadalla, 2013; El-Sherbenie 2004; Abdel-Mageed 2005; Bakry and Arbab, 2020). Because insect sap contains very little protein, the insect may have to suck a large amount of plant sap to get enough protein for growth and egg development. The insects can attack guava leaves, branches, and fruits as a result of a huge loss of plant sap, which in turn manifests as leaf loss, wilting of growing tips, early leaf drop, deformation of leaves and dwarfing (Mangoud, 2000; El-Said, 2006; Reda et al., 2010).

As well as, honey dew, direct damage, which is secreted by these insect pests, enhances saprophytic fungal damage and decreases Plant metabolism and photosynthesis (Mittler and Douglas, 2003; Zaki et al., 2013; El- Sayed, 2015 and Mohamed, 2015). As well as, Mealybugs were difficult to kill because they live in protected areas, the mealybugs body walls on all developing stages are waxed, and most insecticides are ineffective. The immobility of Mealybugs, on the other hand, allows biocontrol chemicals to be successful. (Mani et al. 2011).

R.cardinalis (Coleoptera: Coccinellidae) is specialized on mealybugs. It had its important after its success in controlling Icerya purchasi Maskell in the citrus groves of California and many other countries (Bennett et al., 1985; Caltagirone and Doutt, 1989 and Mohamed et al., 2013). It became one of the most important predators that attack mealybug species in different areas in Egypt (Hamed and Saad, 1989; Ibrahim, 2005; Awadalla, 2013). The green lacewing, C.carnea (Neuroptera: Chrysopidae) is regarded as a common predator of I. seychellarum (Carrillo and Elanov, 2004; El-Serafi et al., 2004). It is regarded as one of the most significant predaceous species because, its extensive distribution, high relative frequency of occurrence, good hunting characteristics, and ease of rearing in the laboratory.

To achieve a good integrated pest management of any pest; ecological and biological aspects should be involved. As a result, the current work aimed to study the population fluctuations of I. seychellarum and its associated predaceous insects (R.cardinalis and C. carnea) and the synchronization between them as well as, the impact of some climatic factors (temperature and relative humidity) on their populations.

MATERIALS AND METHODS

This study was performed for two following years in heavy infested guava orchards with I. seychellarum during (2020/2021) and (2021/2022) at ELbhera, Governorate. The chosen trees did not receive to any chemical treatments throughout the period of this study. All trees received the same routine horticultural practices.

Sampling method and assessment

Five trees were similar in size, shape, height, vegetation and relatively homogenous in their infestation with I. seychellarumm were chosen to carry out this work. Samples of guava leaves were taken biweekly intervals throughout the investigation period from the four cardinal directions; East-West-North and South in addition to, the center of each selected tree. Sample size was 125 leaves represented 25 leaves for each direction. Samples were picked up randomly from each tree by using a garden scissors. The samples were packed instantly in polyethylene bags and transferred to the laboratory on the same day for assessment by using stereoscopic microscope (binocular) to record the number of I.seychellarum (as nymphs and adults). To investigate the population density of the two predators, the five trees were examined in the field and record the numbers of the observed predators which found.

Effect of ecological factors on population fluctuations of I.seychellarumand its associated predators:

Meteorological Central Laboratory, Agricultural Research Center, and Ministry of Agriculture provided us with the data of temperatures, as well as average daily relative humidity, for the seasons 2020/2021 and 2021/2022.We investigated the simple correlation and regression values to study the relationships between the tested weather factors and the population density of the I.seychellarum and its associated predators. Also, multi regression analysis was done to estimate the combined effects of the abiotic factors of I.seychellarum and its associated predators as well as, estimated the combined effects of abiotic and biotic factors on population of seychellarum scale. Correlation also, the regression analyses were done by using SAS program (SAS Instue, 1998).

RESULTS AND DISCUSSION

This study was performed for two following years in heavy infested guava orchards with I. seychellarum during (2020/2021) and (2021/2022) at ELbhera, Governorate. The chosen trees did not receive to any chemical treatments throughout the period of this study. All trees received the same routine horticultural practices.

Sampling method and assessment

Five trees were similar in size, shape, height, vegetation and relatively homogenous in their infestation with I. seychellarumm were chosen to carry out this work. Samples of guava leaves were taken biweekly intervals throughout the investigation period from the four cardinal directions; East-West-North and South in addition to, the center of each selected tree. Sample size was 125 leaves represented 25 leaves for each direction. Samples were picked up randomly from each tree by using a garden scissors. The samples were packed instantly in polyethylene bags and transferred to the laboratory on the same day for assessment by using stereoscopic microscope (binocular) to record the number of I.seychellarum (as nymphs and adults). To investigate the population density of the two predators, the five trees were examined in the field and record the numbers of the observed predators which found.

Effect of ecological factors on population fluctuations ofI.seychellarumand its associated predators:

Meteorological Central Laboratory, Agricultural Research Center, and Ministry of Agriculture provided us with the data of temperatures, as well as average daily relative humidity, for the seasons 2020/2021 and 2021/2022. We investigated the simple correlation and regression values to study the relationships between the tested weather factors and the population density of the I.seychellarum and its associated predators. Also, multi regression analysis was done to estimate the combined effects of the abiotic factors of I.seychellarum and its associated predators as well as, estimated the combined effects of abiotic and biotic factors on population of seychellarum scale. Correlation also, the regression analyses were done by using SAS program (SAS Instue, 1998).

(Fig.1) Population fluctuations of I.seychellaruminfesting guava trees during 2020/2021 (A) and 2021/2022 (B) in El-Behara governorate.

Effect of some weather factors on the seasonal activity of I. seychellarum on guava trees.

Table 1: Simple correlation and regression coefficients between the tested weather factors and each of nymphs, adult females and total populations of I. seychellarum on guava during 2020/2021.

Pre-stage

Weather factors

Simple correlation & partial regression

Multi regression

r

P

b

R^{2}

b

E.V

Nymph

T. MAX

0.58

0.0016

3.29

0.3350

0.8163

37.34

T. MIN

0.58

0.0016

4.01

0.3329

0.3136

RH%

-0.45

0.0198

-3.31

0.1985

0.3077

Adult

T. MAX

0.55

0.0033

2.00

0.3577

0.2186

50.19

T. MIN

0.59

0.0012

2.79

0.4672

0.0193

RH%

-0.38

0.0505

-1.39

0.1010

0.4157

Total

T. MAX

0.62

0.0006

5.29

0.3694

0.5430

43.45

T. MIN

0.63

0.0004

6.80

0.4089

0.1200

RH%

-0.46

0.0168

-4.70

0.1707

0.3201

Impact of temperatures (maximum, minimum) and relative humidity on the totality of population of I. seychellarum during the two studied years were illustrated in Tables (1 & 2). During the first year (Table, 1), there were slow positive relationship between the nymph density of the I. seychellarum (r =0.58) with maximum and minimum temperatures; while, with relative humidity it was negative (r =- 0.45). Multi regression show that the combined effect of weather factors had low effect (E.V. = 37.34 %).

There were slow positive relationship between the adult female population of the I. seychellarum (r = 0.55 & 0.59) with maximum and minimum temperatures; while, with relative humidity it was negative (r = - 0.38). Multi regression show that the combined effect of weather factors had 50.19 % of the total factors affecting adult female population (Table, 1).

There were significant effects of maximum and minimum temperatures on I. Seychellarum total population during the first year (r =0.62 & 0.63) and there were insignificant effects of relative humidity during (r =- 0.46). Multi regression show that the effect combined of weather factors exhibited 43.45% of the total factors affecting total population (Table,1).

In the second year (Table, 2), there were positive relationship between the nymph population of the I. seychellarum (r =0.70 & 0.63) with maximum and minimum temperatures; while, with relative humidity it was negative (r =- 0.68). Multi regression show that the effect combined of weather factors reached 56.32%.

There were positive relationship between the adult female population of the I. seychellarum with maximum and minimum temperatures (r = 0.69 & 0.63); while, with relative humidity there was a negative coloration (r = - 0.68). Multi regression show that the combined effect of weather factors had 56.37 % of the total factors affecting adult female population (Table,2). There were significant positive effects of maximum and minimum temperatures on I. seychellarum total population during the second year (r =0.70 & 0.63). Significant negative effects of relative humidity (r =- 0.68). Multiregression showed that, the influence of weather factors reached 56.37 % (Table, 2).

Table 2: The simple correlation and regression coefficients between the tested weather factors and each of nymph, females and total population of I. seychellarum on guava trees during 2021/2022.

Pre-stage

Weather factors

Simple correlation & partial regression

Multi regression

r

P

b

R^{2}

b

E.V

Nymph

T. MAX

0.70

<.0001

3.44

0.4833

0.6239

56.32

T. MIN

0.63

0.0004

3.81842

0.3971

0.8854

RH%

-0.68

<.0001

-4.69

0.4680

0.0835

Adult

T. MAX

0.69

0.0001

1.47

0.4836

0.6231

56.37

T. MIN

0.63

0.0004

1.64

0.3972

0.8864

RH%

-0.68

0.0001

-2.01

0.4687

0.0829

Total

T. MAX

0.70

0.0001

4.91

0.4834

0.6236

56.37

T. MIN

0.63

0.0004

5.46

0.3971

0.8857

RH%

-0.68

0.0001

-6.71

0.4682

0.0833

3- Seasonal activity of R. cardinalis and C.carnea on guava trees:

Data presented in Fig. (2 A&B) illustrated that seasonal activity of R. cardinalis and C.carnea had two peaks on guava trees during first and second years.

Population of R. Cardinalis recorded its first peak on the 24^{th } of October and 20^{th }of November (with 31 and 26 individuals /sample), throughout the first and second year, respectively. The second peak was recorded on the 22^{th }of May and 4^{th} of June with 23 and 34 individuals / sample, respectively (Fig., 2).

With respect to C. carnea population (Fig., 2), it recorded its first peak on the 7^{th }and 20^{th} of November of first and second year (14.1 and 8 individuals /sample, respectively). The second peak was recorded on the 22^{th} and 7^{th} of May of first and second year (19 and 23.1 individuals/ sample, respectively).

(Fig.2)Seasonal activity of R.cardinalisand C.carnea on guava trees infested with I. seychellarum during 2020/2021 (A) and 2021/2022 (B) in El-Behara governorate.

Impact of some climatic factors on the seasonal activities of R. cardinalis and C.carnea on guava trees.

Impact of temperatures (maximum & minimum) and (R.H %) on the populations of R. cardinalis and C. carnea throughout the two years of study were illustrated in Tables (3 and 4).

There were positive relationship between the R. cardinalis and both of maximum & minimum temperatures (r =0.68 and 0.66) during the first year; while, with relative humidity it was negative (r =- 0.56). Multi regression show that the combined effect of weather factors 51.81% of total factors affecting R. cardinalis (Table, 3).

There were no relationship between the C. carnea population and both of maximum & minimum temperatures (r = 0.19 and 0.01) during the first year; while, with relative humidity it was significantly negative (r = - 0.49). Multi regression show that the combined effect of weather factors had a moderate effect (E. V = 35.51%) (Table,3).

Table 3: The simple correlation and regression coefficients between the tested weather factors and populations of R. carinalis and C. carneaduring 2020/2021.

Tested factors

Simple correlation & partial regression

Multi regression

r

P

b

R^{2}

b

E.V

R. cardinalis

T. MAX

0.68

<.0001

0.87

0.4607

0.8298

51.81

T. MIN

0.66

0.0002

1.03

0.4362

0.2427

RH%

-0.56

0.0023

-0.94

0.3155

0.2427

C. carnea

T. MAX

0.19

0.3453

0.17

0.0357

0.1958

35.51

T. MIN

0.01

0.9552

0.01

0.0001

0.0952

RH%

-0.49

0.0090

-0.59

0.2429

0.1356

There were positive relationship between the R. cardinals and temperatures (maximum and minimum where r-values were 0.66 and 0.63) during the second year; while, with relative humidity it was negative (r =-0.49). Multi regression show that the combined effect of weather factors contributed 44.25% of the total factors affecting R. cardinalis (Table, 4).

There were relatively low effect of maximum and minimum temperatures on C. Carnea population during the second year (r = 0.42 and 0.27); while, with relative humidity it was significant (r = - 0.57). Multi regression show that the combined effect of weather factors had moderate effect (E.V. = 44.12%) (Table, 4).

Table 4: Simple correlation and regression coefficients between the tested weather factors and populations of R. cardinalis and C. carnea during 2021/2022.

Tested factors

Simple correlation & partial regression

Multi regression

r

P

b

R^{2}

b

E.V

R. cardinalis

T. MAX

0.66

0.0002

0.61

0.4406

0.3852

44.25

T. MIN

0.63

0.0004

0.71

0.3952

0.9504

RH%

-0.49

0.0096

-0.63

0.2394

0.8454

C. carnea

T. MAX

0.42

0.0281

0.35

0.1786

0.0467

44.12

T. MIN

0.27

0.1750

0.27

0.0723

0.0445

RH%

-0.57

0.0017

-0.66

0.3301

0.3319

Synchronization between I.seychellarum and its predators.

Correlation coefficient values between predators (R. cardinalis and C. carnea) populations and each of the nymphs, females and totality of population of I. Seychellarum during the two studied years are represented in Table (5). There were positive relationship between the R. cardinalis and each of nymphs (r =0.69 and 0.78), adult females (r =0.62 and 0.76) and total population (r =0.72 and 0.77) during the first and second year, respectively.

As it was noticed with R. cardinalis, the was a good synchronization between C. Carnea population and each of nymphs (r =0.63 and 0.61), adult females (r =0.29 and 0.56) and total population of I. seychellarum (r =0.54 and 0.57) throughout 1^{st} and 2^{nd} seasons, respectively (Table, 5).

Table 5: The correlation coefficient values between denisities of predators(R. cardinalis and C. carnea) and each of nymphs, adult females and total populations of I. seychellarumin guava orchard during 2020/2021 & 2021/2022.

Prey

Stage

2020 - 2021

2021 - 2022

R. Cardinalis

C. carnea

R. Cardinalis

C. carnea

Nymph

0.69

<.0001

0.63

0.0004

0.78

<.0001

0.61

0.0098

Adult

0.62

0.0006

0.29

0.1373

0.76

<.0001

0.56

0.0099

Total

0.72

<.0001

0.54

0.0039

0.77

<.0001

0.57

0.0008

Combined effect of ecological factors on I.seychellarum population:

The combined effect of abiotic (maximum, minimum temperatures and relative humidity) and biotic factors (R. cardinalis and C. carnea) represented by R^{2} (0.90, 0.87 and 0.91) of the total factors affecting nymphs, adult females of I. seychellarum throughout the 1^{st} season. On the other hand, throughout 2^{nd} season these effects recorded R^{2 }(0.79,0.71 and 0.77) of the total factors affecting nymphs, adult females, respectively. The mathematical relationships between I. seychellarum populations (nymphs, adult females and total) and abiotic & biotic factors are represented as follows:

Total = -87.91-4.07 TMax +6.33 Tmin +1.42RH +5.60R.cardinalis +1.88 C. carnea

These results were agreed with those obtained by (Abdel-Rahman et al. 2007), who reported, there were significant positive correlations with temperature degrees and insignificant negative correlations with relative humidity on mango orchards which infested by I. seychellarum. Moustafa (2012) indicated, there were positively high significant correlations between I. seychellarum population and the mean of temperatures and relative humidity at Damietta governorate.

Also, the current results were agreed with those obtained by Ghanim et al. (2013) and Mohamed (2013); they indicated that, the predator, R. cardinalis is the most predator of I. seychellarum on citrus and grapevine orchards in Dakahlia governorate. Also, the above results were agreed with those obtained by El-Sherbenie(2004); who recorded that, the predator R. cardinalis is the most widespread predator on I. seychellarum in guava orchards. Abdel-Mageed (2005), Abdel-Aleem (2008) and Moustafa (2012) added that, R. cardinalis was the dominant insect predator associated withI. Seychellarum, Hamid and Hassanian(1991), R. cardinalis associated with Icerya spp..

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