Three Releasing Doses of Trichogramma Sp. (Hymenoptera:
Trichogrammatidae) with Bacillus Thuringiensis Kurstaki in Controlling of Batrachedra Amydraula Meyrick Eggs on Date Palm
Trees
Ghazwan Alsaedi
Date Palm Research Center / University of Basrah - Basrah-Iraq [email protected]
Summary
The efficiency of two Trichogramma species Trichogramma brassicae and T.
embryophagum in combination with bacterial suspension of Bacillus thuringiensis in controlling of the lesser date moth, Batrachedra amydraula Meyricke. Three release doses (50, 100 and 200 parasitoids/tree) for each species were examined in farm and the parasitism rate, adult’s emergence, the number of females and adult longevity of T. brassicae and T. embryophagum were studied. The results showed that both Trichogramma species were significantly efficient, especially at higher dose (200 parasitoids/tree), in their parasitism activity on B. amydraula eggs.
However high reduction in infestation was achieved by B. thuringiensis with T. embryophagum (70.1%) at concentration of 106 cell/ml B. thuringiensis. In addition, no significant differences was obtain between T. brassicae and T. embryophagum in mortality and adult emergence rates when they were treated with/without B. thuringiensis reared in the B. amydraula. However, the longevity of T. embryophagum was significantly more than T. brassicae. This is the first study to investigate T. embryophagum for parasitizing the eggs of B. amydraula and results of present study suggested that T. embryophagum with B. thuringiensis could be more effect for biocontrol of B. amydraula.
Keywords: Batrachedra amydraula, Bacillus thuringiensis, Date palm, Natural enemies, Trichogramma species, control parameters.
1.Introduction
Date palm (Pheonix dactylifera L.) is a very important economic crop in different countries (Abass and Maziel, 2019). Several factors Such as pests, weather conditions and diseases affected the plant health. The lesser date moth Batrachedra amydraula Meyricke
(Cosmopteridae: Batrachedridae) in Iraq is a dangerous pest of date palm (Downson and Aten, 1962; Levi Zada et al. 2011; Haldhar et al. 2017). The harmful phase of the pest is the larva feeding inside the fruit and larvae spin webs around flowers and later infest the fruit and may damage three or four fruits during its lifetime.
Using pesticides have been influenced the relation between date palm pests and there natural enemies, wherefore the Integrate Pest Management programs become more convoluted when different pests increased (Latifian, 2001; Latifian and Zaerae, 2009; Latifian , 2012).
Wasps of the genus Trichogramma (Hymenoptera: Trichogrammatidae) are among the most commonly used groups of natural enemies because they are relatively easy to culture and are among the most important egg parasitoids of lepidoptera agricultural pests, Trichogramma wasps have been commercially applied as mass releases in over 32 million hectares against more than 30 key pests worldwide (Wajnberg and Hassan 1994; Smith 1996; Ayvaz and Karaborklu 2008;
Pizzol et al. 2010, 2012).
Otherwise T. brassicae Bezdenko is used widespread for the control of lepidoptera pests in another studies on different plants, Alsaedi et al. (2016) have suggested that there will be good chances and new choices for putting T. brassicae, T. evanescens and T. embryophagum within style of valuable assets of any of the Integrate Pest Management strategies against Tuta bsoluta in order to reduce the use of chemicals. Furthermore, the characteristics of both host species and the host plant on which the pest acts effect on host selection by parasitoids (Chau and Mackauer, 2001; El-Wakeil ,2007; Desneux and Ramirez-Romero, 2009). Female parasites usually accept host eggs of the same size or larger than their host. The size of the original host affects the rates of natural host intrusion in the field (Nurindah et al. 1999). Otherwise, the performance of Trichogramma releases depend on the biological characteristics of the parasitoid species, strains used and on their interactions with a specific pest-plant system (Tabone et al. 2010; Andrade et al. 2011; Yuan et al. 2012). The biological control programs is critical when Trichogramma generations developing within a crop can play a pivotal role (Mills, 2010). Meanwhile, the bacterial bio-insecticide, Bacillus thuringiensis kurstaki (Btk) is considered as one of most powerful biocides and widespread to combat larvae of lepidopteron species (Lacey, 2001).
In the current study, the efficiency of three doses of these parasitoids in the control of B.
amydraula in date palm was investigated in Basrah orchards. Our main goal was to determine
how T. brassicae and T. embryophagum exploit the egg distribution of B. amydraula on date palm and this is the first study for use T. brassicae and T. embryophagum in control B.
amydraula on date palm.
2.Materials and Methods 2.1.Production of the host
Insects were collected from the University of Tehran, Department of Plant Protection, Ecology and Behavior Lab (Karaj, Iran). The parasitoid, Trichgramma brassicae and T.
embryophagum were mass-produced on eggs of the Mediterranean flour moth, Ephestia kuehniella (Lepidoptera: Pyralidae). The insect was reared in the laboratory on wheat flour in a climate chamber (25±2°C, 70% RH, L16:D8). Moths were collected daily and were confined in oviposition cages (40cm long and 18 cm in diameter) made of metal body covered with wire screen, collected eggs were used for reification and /or rearing of the parasitoid. Only mated 2–4 days old wasps were used in the experiments.
2.2.Rearing of the parasitoid
Eggs of E. kuehniella were glued onto cardboard cards, 6x4 cm, each one contained 50, 100 and 200 eggs. Rearing of T. brassicae and T. embryophagum conducted in glass jars 21cm high and 10 cm in diameter covered with muslin cloth kept in position by means of rubber bands.
Six cards of newly deposited eggs (one day old) were confined in each glass jar with two cards containing parasitized eggs witch give rise to parasitoid adults within 24 hours. Rearing of E.
kuehniella , T. brassicae and T. embryophagum took place at a temperature of 25±2°C, 70% RH, L16:D8.
2.3.Releasing of the parasitoid
Each card containing parasitized eggs (50, 100 and 200 eggs). A piece of cardboard 6 x 8 cm was bound to make an envelope like which was clipped with a double piece of thread by means of a stapler. This envelope protects the parasitized eggs from predators as well as from sun radiation. Each releasing envelope contained one small piece of cardboard (50, 100 and 200 eggs) having three different ages of parasitized eggs so that the parasitoids emerged in three
waves at three – day intervals. Releasing took place before sun set to avoid sun heat ( El- Dakroury et al., 2002).
2.4.Formulation of Bacillus thuringiensis (Bt)
The Bt formulation used in the experiments was Bacillus thuringiensis sbspecies kurstaki (106 cell/g) WP, Biolep, Biorun Company, Iran, serial dilution of Bt was prepared using 0.5g wet table powder and dissolved in 1000ml of water.
2.5.Field Trials
Studies were conducted in Basrah during 2018. Orchards of date palm variety Halawi represented about 5Km were used. Releasing of parasitoids was carried out during 2018 in the beginning of March. Three releasing envelopes (50, 100 and 200 eggs) were hanged on palm tree branches (2meters high).
Samples size was 10 strands / one date palm taken at random from ten replicates. In any assessment fruit having alive larvae of B. amydraula or dropped fruit but having the webbing silk and or faces in their places were recorded.
2.6.Statistical analysis
The parameter characteristics were provided as mean ± standard error (SE). The parameter characteristics among two Trichogramma species were compared using one way analysis of variance (ANOVA). Comparisons between the mean of treatments were done using the Duncan’s test (P< 0.05). Statistical analysis was performed using the software SPSS Statistics for Windows Version 21 (SPSS 2012), and for infestation figures and reduction % was calculated based on Abbott (1925).
3.Results and Discussion
The results of releasing three densities of either Trichogramma brassicae or T.
embryophagum for control of B. amydraula have been summarized in Fig. 1 revealing that the highest control percentage (58%) of lesser date moth, B. amydraula infestation was achieved by release of parasitoids at rate of 200 adult per date palm tree. The results also differ significantly with that achieved (33%) by the release of parasitoids at rate of 100 parasitoids/palm tree. While,
releasing parasitoid at the rate of 50 parasitoids/palm tree resulted in 23.5% control efficacy. In otherwise the activity rate of T. brassicae were 47.5, 26.4, and 17.1% when 200, 100, and 50 adult females per date palm were released in the orchard; respectively. These values of the parasitism rate of T. embryophagum were significantly higher than the respective parasitisim rate of T. brassicae, which were the densities of 200, 100, 50 parasitoid per plant (Fig. 1).
Alrubeai et al. (2014) released of T. evanescens at rate of 1000 parasitoids/palm tree were a good option to control the lesser date moth as alternative method to chemical control.
Mohammad et al.(2011) illustrated that infestation levels of lesser date moth in Al-Anbar Governorate, Iraq, were reduced significantly after two weeks of releasing 100, 200 and 300 T.
evanescens or T. principium/palm tree, with higher efficiency for T. evanescens and two parasitoids were effective in reducing the infestation by this pest on date fruit during both hababook and chemri stages for all release rates.
The results in Fig. 2 obtained, Elucidated ratio of mortality in which T. embryophagum which was low (36.05 and 36.17%) using the following respective doses of 200 and 50 parasitoids/plant respectively. Similar results were obtained releasing T. brassicae 40 and 41.66% using the following respective doses of 200 and 50 parasitoids /plant. Evidently, the ratio of adults emergence and number of female of T. embryophagum in all the releases were significantly higher than in T. brassicae (Figs. 3 and 4). Although, the mortality of T.
embryophagum was constantly lower than T. brassicae, the difference between the mortality of these two parasitic wasps was only significant when 200 adult females per plant were released in the cage (Fig. 2). Additionally, the rate of adult emergence and the proportion of females of T.
embryophagum were constantly higher than T. brassicae. However, their differences were only significant in the density of 200 and 100 adult female per plant, respectively (Figs. 3 and 4).
Gameel et al. (2014) showed the reduction increased of B. amydraula after the successive parasitoid releasing to reach the high level (75.06%) by releasing of T. evanescens for one time by the rate of ten releasing 20,000 parasitized eggs/4200m2 induced a remarkable reduction in the infestation levels with the greater date moth and the lesser date.
The reduction of B. amydraula on date trees treated with T. brassicae or T. embryophagum as well as B. thuringiensis (Bt) suspension presented in Fig. 5. Significant reduction was
observed in the B. amydraula on date treated with T. embryophagum in combination with B.
thuringiensis (F= 54.103; df= 4; P ≤0.001). In fourth treatment (T4), an average of the reduction 39.2 of B. amydraula were recorded 70.1.
Mohammad et al. (2011) illustrated that infestation levels of lesser date moth in Al-Anbar Governorate, Iraq, were reduced significantly after two weeks of the release of 300 Trichogramma evanescens or T. principium/palm tree, with higher efficiency for T. evanescens.
Finally, it could be useful recommended that, the release of egg parasitoid T. brassicae or T. embryophagum for one time by the rate about of 200 egg/tree gave a good results to control B.
amydraula. Promising data were obtained and hoping carrying out more work to assure these results. This study may ensure the importance of the utilization of Trichogramma parasitoid to control pests in date fruits to obtain a good bio-product.
17.1
26.4
47.5
23.5
33 y = 0.0204x + 6.55 58
R² = 0.9991 y = 0.0233x + 11
R² = 0.996
0 10 20 30 40 50 60 70
0 50 100 150 200 250
T. brassicae T. embryophagum
Parasitism (%)
Number of Trichogramma/plant
Figure 1: The parasitism according to releasing doses of Trichogramma sp. on the B. amydraulaeggs.
ab
a
bc ab
a
c
y = -0.054x + 57.23 R² = 0.055 y = -0.027x + 45.42
R² = 0.037
0 10 20 30 40 50 60 70 80 90 100
0 50 100 150 200 250
bc
c ab bc
c
a
y = 0.054x + 42.76 R² = 0.055 y = 0.027x + 54.58
R² = 0.037
0 10 20 30 40 50 60 70 80 90 100
0 50 100 150 200 250
Mortality (%)
T. brassicae T. embryophagum
Figure 2: The mortality according to releasing doses of Trichogramma sp. on the B. amydraulaeggs.
Adult emergence (%)
Number of Trichogramma/plant
T. brassicae T. embryophagum
Figure 3: The Adult emergence according to releasing doses of Trichogramma sp. on the B.
amydraulaeggs.
c c
a bc
b
a
y = 0.176x + 25.85 R² = 0.878 y = 0.128x + 43.02
R² = 0.876
0 10 20 30 40 50 60 70 80 90 100
0 50 100 150 200 250
39.2
54.5 55.4
70.1
15.3
0 10 20 30 40 50 60 70 80 90 100
T. brassicae T. brassicae+Bt T. embryophagum T. embryophagum+Bt control T. brassicae T. embryophagum
Female (%)
Number of Trichogramma/plant
Figure 4: The number of female according to releasing doses of Trichogramma sp. on the B. amydraula eggs.
Treatments
Figure 5: Mean reduction in infestation of B. amydraula mines per tree according to release T. brassicae and T. embryophagum with/without Bt in comparison to the control.
Reduction in infestation %
F=54.103 df=4 P≤0.001
4.Conclusion
Altogether, our results favour the use of locally-available species of Trichogramma wasps, for a safe and effective inclusion in Integrated pest management (IPM) programs against B.
amydraula, Although, future studies are needed to optimize parasitoid release rates, as well as complementarities with other management procedures such as predator release, pheromone traps and insecticides, for desirable results. Our findings provide new insight for putting these parasitoids, particularly T. embryophagum, within the sort of valuable assets of any of the integrated pest management (IPM) strategies against B. amydraula in order to reduce the use of chemicals.
5.Acknowledgements
The author wish to thank Prof.D. Ahmad Ashouri in the Department of Plant Protection, University of Tehran, Karaj, Iran for providing the insects for this research work.
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