In the first season (2012-2013):

The population densities of H. cubana (Table 2 and Figure 2) were in low levels of abundance at the beginning of the season during March (monthly means of 11.0, 7.3, 10.0 and 1.3 individuals/sample of Cunningham, Nativa, K636, and KX2; respectively), then increased to moderate levels of abundance during April (monthly means 159.0, 137.8, 87.0, 95.8 individuals/sample). After that, two peaks were occurred before the first harvest during May (monthly averages were 244.8, 194.8, 220.0, and 101.8) and June (200.3, 111.0, 110.5 and 54.0 individuals/sample) on Cunningham, Nativa, K636, and KX2; respectively as shown in (Table 2; Figure. 2). Afterwards, the numbers of H. cubana rapidly declined during the next four months (July and October) till harvest in November. Then, the third peak was recorded in December directly after the harvest of November (monthly means 7 422.3, 8 465.0, 3 866.0, 2 829.0 individuals-sample) on Cunningham, Nativa, K636 and KX2; respectively.

In the second season (2013-2014):

An intensive invasion of Psyllid population (Table 3 and Figure 3) occurred in the beginning of the season with obvious differences between Psyllid densities on Leucaena genotypes. The first peak occurred in February for Leucaena genotypes (monthly means were 8 056.75, 8 880.75, 4 705.25 and 580 individuals-sample on Cunningham, Nativa, K636, and KX2; respectively). Afterwards, the populations of Psyllid were in lowest levels of abundance in April with monthly means 17.5, 13.5, 17.75 and 27 on Cunningham, Nativa, K636, and KX2; respectively. The second peak recorded in June (monthly means were 298.75, 199, 189.5 and 81 individuals/sample on Cunningham, Nativa, K636, and KX2; respectively). The moderate levels of infestations occurred in August, after that the population fluctuated slowly at October in Leucaena genotypes (Table 3 and Figure 3).

In the first season (2012-2013):

T. tabaci showed low levels of initial infestation (Table 2 and Figure 2) in March 211.5, 171.5, 149.5, and 62.0 individuals/sample on Cunningham, Nativa, K636 and KX2; respectively. Then, the population density grew up slowly on all Leucaena genotypes, with observation of high mean numbers of Thrips on Cuninngham more than other genotypes during April (monthly means were 544.8, 372.5; 258.0 and 272.5 individuals/sample on Cunningham, Nativa, K636 and KX2; respectively). Four peaks of Thrips were recorded on Cunningham, Nativa and K636 during May to Aug. The monthly means of May were 745.0, 567.3, 469.0; means of June were 837.5, 918.3, 715.0; means of July were 850.5, 809.0, 412.0; and means of August were 479.0, 483.0, 463.3 individuals/sample on Cunningham, Nativa and K636; respectively. Besides, two peaks were occurred on KX2 in May and June with monthly means 409.0, 621.3 individuals/ sample; respectively. After that a sharp declines of population densities occurred throughout the following months. The pest totally disappeared in December after the 1st harvest.

In the second season (2013-2014):

Thrips population were in low levels of abundance (Table 3 and Figure 3) in February for Leucaena genotypes (monthly means were 3.25, 0.0, 0.0 and 0.0 individuals/sample of Cunningham, Nativa, K636, and KX2; respectively). Afterwards, the population of Thrips showed two peaks in April and June. The mean numbers in April were 560.25, 659.75, 480.25 and 300.25 on Cunningham, Nativa, K636, and KX2; respectively. The means of the second peak of June were 759.75, 975.25, 827 and 688.5 individuals/sample on the same respective genotypes. Thereafter, the moderate levels of abundance were recorded in August (monthly means 477.5, 415, 213.5 and 81.5 on Cunningham, Nativa, K636, and KX2; respectively), after that the populations were reduced at the end of the season in October on almost Leucaena genotypes.

During The first season (2012-2013):

The Leucaena Psyllid; H. cubana showed the strong correlation with natural enemies (Table 2) for Cunningham (r= 0.80), weak for KX2 (r= 0.16), and moderate (r= 0.61 and 0.47) for Nativa and K636; respectively. On the other side, the correlation was strong between T. tabaci and natural enemies for Cunningham (r= 0.47), weak for K636 (r= 0.06), and the moderate (r= 0.35 and 0.17) for Nativa and KX2; respectively.

During the second season (2013-2014):

The correlations (Table 3) between natural enemies and Psyllid were strong (r= 0.94 and 0.91, for K636 and KX2 respectively), the moderate relation was recorded for Nativa (r= 0.70), and weak for Cunningham (r= 0.572). However, the correlation between natural enemies and Thrips were negative in Leucaena genotypes.

In the first season (2012-2013):

H. cubana individuals showed three generations a year, two before harvest in May and June, and the third peak in December after harvest. Because, an obvious reductions were observed in natural enemies populations during peaks times compared by the actual numbers of Psyllid. This could be due to the new generation overlapping and the effects of high temperatures in the dry seasons during May and June at Merida, Yucatan which reduce the populations of natural enemies. These results are in agreement with those reported by ^{Funasaki et al. (1989)} who stated that C. coeruleus failed to be established in many seasonal dry areas. Therefore, Psyllid numbers increased more than natural enemy’s agents, and this affected other biological control agents such as P. yaseeni which can’t overcome Psyllid peaks during high Psyllid numbers.

^{Geiger and Andrew (2000)} stated that P. yaseeni never succeeded in regulating Psyllid populations in the presence of high Psyllid populations. Accordingly, the peaks were occurred when the Psyllid population was out of control during the absence of biological control agents, because natural enemy’s agents automatically control Psyllids populations, according to the findings of (^{Bray 1994}; ^{Napompeth 1994}; Geiger et al. 1995; ^{Valenciaga et al. 1999}; ^{Singh 2004}; ^{Shivankar et al. 2010}). The third peak after harvest could be occurred due to the young leaves production of Leucaena, which supported about 98% of H. cubana infestation, because juvenile leaves encourage females for egg-laying. This is in accordance with those reported by (^{Chazeau et al., 1989}).

In the second season (2013-2014):

The low Psyllid population during non-harvested Leucaena genotypes at February, 2013of the first season, and the outbreak of pest in all Leucaena genotypes during February, 2014 emphasized that the harvest was the reason for the first peak, because the new and juvenile leaves of leucaena genotypes after harvest supported Psyllids females for egg-laying. This is in agreement with (^{Chazeau et al., 1989}). Therefore, the natural enemies weren’t able to control the outbreak of Psyllid because there were clear differences between pest and natural enemies’ densities in all Leucaena genotypes (Table 3). However, this difference impedes the efficiency of many natural enemies. This is in accordance with (^{Geiger and Andrew 2000}). The second peak of June which happened in the previous season under non-harvested trees occurred due to the normal time of overlapping generation. Consequently, the population reduced in August and October, due to the low temperatures during these months in Merida, Yucatán, Mexico. The same results were found by Anonymous (2014) where the reproduction and development of Psyllid were stopped or declined during cool weather and most species have 3 to 5 generations a year and some species may have one generation a year.

In the first season (2012-2013):

The four peaks of T. tabaci on Cunningham, Nativa, and K636 during May to Aug. and the two peaks of KX2 during May and Jun could be due to the numbers of overlapping generations which depend on the climatic factors (especially maximum temperature), host plant, and the numbers of natural enemies. (^{Bastos et al. 1981}) recorded four population peaks of Thrips in Brazil which represented four generations of the pest. Nevertheless, the variation in the present results could be attributed to the differences between Leucaena genotypes. The highest grand total numbers of T. tabaci (Table 2) was occurred on the susceptible genotypes; Cunningham and Nativa. These are in agreement with ^{Castillo et al. (1997)}, who found that, the most susceptible lines were Cunningham (L. leucocephala) and Nativa (L. leucocephala x L. pallida) which showed moderately resistance among different Leucaena accessions to pest infestation.

Besides, the differences between the fluctuations of the natural enemies on Leucaena genotypes, this may explain such variation in the numbers of peaks among Leucaena genotypes. Additionally, it seems that T. tabaci populations were out of control under the effect of natural enemies, because low population densities of the natural enemies were found on Cunningham, Nativa, and K636 compared with the numbers of T. tabaci during the four peaks, and as it known that natural enemies automatically regulating the numbers of Leucaena pests (^{Shivankar et al. 2010}; ^{Singh 2004}; ^{Bray 1994}; ^{Napompeth 1994}).

In the second season (2013-2014):

The Thrips fluctuated slowly (Table 3) in the beginning of the season in February for Leucaena genotypes, because the high densities of natural enemies kept Thrips populations under control. Afterwards, the population of the pest increased due to the total absence of natural enemies which encouraged peaks formation on Leucaena genotypes during April. Likewise, in the next month of June the low population of natural enmies permits pest outbreak. These results are in agreement with ^{Alston (2008)} who reported that the plenty of natural enemies are adequate to suppress Thrips population.