Survey of The Main Pests Infesting Squash Plants and Its Relation with The Planting Dates at Assiut Governorate

Field experiments were conducted in Assiut Governorate during two successive seasons 2018 and 2019; to survey the phytophagous pests inhabiting squash plants, in addition, to study the relationship between the main pests namely; melon aphid, Aphis gossypii (Glover); whitefly, Bemisia tabaci (Genn.); two-spotted spider mite, Tetranychus urticae Koch; Onion thrips, Trhips tabaci (Lind.) and green leafhopper, Empoasca decipiens (Paoli) and its infestation of the winter, summer and nili squash plantations during 2018 and 2019 growing seasons. The results revealed clearly twenty species of phytophagous pests belonging to twelve families and seven orders inhibiting winter, summer, and nili squash plantations were encountered by using the plant samples method. Data also, revealed that the summer squash plantation received a higher average number with the aforementioned main pests, followed by nili and winter squash plantations; also, the whitefly, B. tabaci ranked first in the highest average number of individuals followed by a two-spotted spider mite, T. urticae ; green leafhopper, E. decipiens ; melon aphid, A. gossypii, and onion thrips, T. tabaci infestation to winter, summer and nili squash plantations during 2018 and 2019 growing seasons. It can be concluded that severe injury of the main pests; A. gossypii, B. tabaci, T. urticae, T. tabaci and E. decipiens to the squash plants can be avoided by using the winter plantation date followed by nili and summer plantation dates.


INTRODUCTION
Squash (Cucurbita pepo L.) is one of the most important vegetable crops used as human food cultivated in Egypt and many countries of the world. The cultivated area with this crop increased during the last two decades especially in new reclaimed regions in both open and protected plantations. Through the growing season, squash plants are suffering from severe infestations with different phytophagous pests from seedling until harvest such as the melon aphid, A. gossypii (Glover); the whitefly, B. tabaci (Genn.); the two-spotted spider mite, T. urticae Koch; the onion thrips, T. tabaci (Lind.) and the green leafhopper, E. decipiens (Paoli) which caused extensive damage not only by sucking plant juice but also by the transmission of phytopathogenic and in decreased the yield. Confirmed results were reported by some investigators such as; Mohamed (2011), Hassan et al. (2013), El-Dars et al. (2013), Al-Kiridis (2016), Al-Ghamdi et al. (2018), Hegab (2018), and Saad (2020).

MATERIALS AND METHODS
The experiments were conducted in the graduate youth lands at Arab El-Awamer, Abnob, Assiut Governorate throughout three successive winter, summer, and nili plantations during 2018 and 2019 growing seasons. An area of about one carat was sown with squash seeds (Cucurbita pepo L.) on half January, May and September months for winter, summer and nili plantations respectively during 2018 and 2019 growing seasons. The experimental design used was completely randomized blocks with three replicates. All recommended agricultural practices were applied during the growing seasons except using chemical control. Weekly samples of 10 leaves from each replicate (in addition to observations) were taken randomly about after three weeks from planting date and continued to harvesting time. The collected leaves were transferred to the laboratory into plastic bags for identification of phytophagous pests and counting the numbers of the main pests; aphid (adults and nymphs); whitefly (immature stages); two-spotted spider mite (moving stages); onion thrips (adults and nymphs) and green leafhopper (adults and nymphs) by the aid of a binocular microscope. Obtained data were statistically analyzed by applying the analysis of variance (ANOVA) and the least significant difference (L.S.D.) at a probability level of 0.05.

Survey the Phytophagous Pests Inhabiting Squash Plants:
Data Table (1) indicates the presence of 20 species of phytophagous pests belonging to twelve families and 7 orders inhabiting squash plants through the winter, summer and nili plantations during 2018 and 2019 growing seasons. Order Hemiptera (Homoptera and Heteroptera) ranked first in the number of species inhabiting squash plants (8 species), followed by Diptera (4 species), Coleoptera (3 species), Acari & Lepidoptera (2 species/each) and Thysanoptera recorded one species, found on previous three squash plantations during two successive seasons 2018 and 2019. The present findings agree with obtained by, Amro (2008) who recorded twenty-one arthropod species belonging to 18 genera, 11 families and four orders were encountered by using the sweeping net method inhabiting sweet melon, cucumber, and squash vegetables during 2005 and 2006 successive seasons, Hagrass et al. (2008) who indicated that 56 species of mites belonging to 44 genera and 24 families were collected from cantaloupe and squash vegetables during 2000 and 2001 growing seasons and Ibrahim et al. (2017) who recorded ten insect pests belonging to nine families and six orders on cucumber. Also, Habashi & Faris (2005), Allam (2014), Abdel-Rahman et al. (2016) and El-Mesawy (2018).

The Main Pests Infesting Squash Plants: I-Melon Aphid, A. gossypii (Glover):
Data obtained in Table (2) cleared that the infestation of aphid on squash plantations (winter, summer and nili) during two successive seasons, 2018 and 2019.

1-Winter Plantation:
The infestation of aphid to squash plants started from 1 st week of February and continued until the 4 th week of April during the 2018 and 2019 growing seasons. Regardless of squash plants and seasons, the highest average numbers of aphid were recorded on squash plants that occurred on 1 st and 2 nd weeks of April (38.00 and 40.67) during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers monthly of A. gossypii were 94.67 recorded during April followed by 37.33 in March and 3.00 in February; and 106.00 recorded during April followed by 61.67 in March and 4.67 in February during 2018 and 2019 growing seasons, respectively.

2-Summer Plantation:
The infestation of A. gossypii to squash plants started from the 1 st and 2 nd weeks of June and continued until the 4 th week of August during 2018 and 2019 growing seasons. Also, the highest average numbers monthly of aphid were 104.67 recorded during August followed by 62.99 in July and 5.33 in June; and 118.00 recorded during August followed by 74.66 in July and 7.33 in June during 2018 and 2019 successive seasons, respectively. The highest average numbers of A. gossypii recorded on squash plants occurred on the 1 st and 2 nd weeks of August (39.00 and 41.67) during 2018 and 2019 growing seasons, respectively.

3-Nili Plantation:
The infestation of aphid to squash plants started from the 1 st and 2 nd weeks of October and continued until the 4 th week of December during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers of A. gossypii were recorded on squash plants that occurred in the 2 nd week of October (37.33 and 41.67) during the 2018 and 2019 growing seasons, respectively. The highest average numbers monthly of aphid were 109.00 recorded during October followed by 44.33 in November and 4.33 in December, and 121.66 recorded during October followed by 54.01 in November and 5.67 in December during two seasons 2018 and 2019, respectively. These results are in partial agreement with those obtained by, Metwally et al. (1995) who recorded that the aphid, A. gossypii started to infest summer squash plantation more early when the plants reached two weeks in age during 1991 and 1992 growing seasons, Kamel et al. (2000) who indicated that, A. gossypii infest cantaloupe summer plantation during 1995 and 1996 successive seasons, Meligi (2009)  It could be concluded from the aforementioned obtained results, the highest general mean numbers of A. gossypii recorded on squash plants were (172.99 and 199.99)

1-Winter Plantation:
As shown in Table (3), the infestation of B. tabaci to squash plants started from 1 st week of February and continued until the 4 th week of April during 2018 and 2019 growing seasons. Also, the highest average numbers of whitefly were recorded on squash plants occurred on the 2 nd and 3 rd weeks of April (172.00 and 179.00) during 2018 and 2019 growing seasons, respectively, and the highest average numbers monthly of B. tabaci were 529.67 recorded during April followed by 239.67 in March and 37.00 in February; and 558.33 recorded during April followed by 251.68 in March and 45.00 in February during 2018 and 2019 growing seasons, respectively.

2-Summer Plantation:
The infestation of whitefly to squash plants started from the 1 st and 2 nd weeks of June and continued until the 4 th week of August during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers monthly of B. tabaci were 547.33 recorded during August followed by 259.33 in July and 45.34 in June; and 596.67 recorded in August followed by 277.01 in July and 55.33 in June during 2018 and 2019 growing seasons, respectively. The highest average numbers of whitefly recorded on squash plants occurred on the 1 st and 3 rd weeks of August (184.33 and 193.00) during 2018 and 2019 growing seasons, respectively.

Nili Plantation:
The infestation of whitefly to squash plants started from the 1 st and 2 nd weeks of October and continued until the 4 th week of December during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers of B. tabaci were recorded on squash plants that occurred in the 3 rd and 2 nd weeks of October (173.00 and 180.00) during 2018 and 2019 growing seasons, respectively. The highest average numbers monthly of B. tabaci were 535.00 recorded during October followed by 242.00 in November and 37.99 in December; and 562.33 recorded during October followed by 255.68 in November and 49.00 in December during two seasons 2018 and 2019, respectively. These results are in partial agreement with those obtained by some investigators such as; Metwally et al. (1995) who recorded that the immature stages of B. tabaci occurred in high numbers on nili squash leaves through all the period of its growing seasons, 1991 and 1992 showing two peaks of population activity, and whitefly started to infest summer squash more early when the plants reached two weeks in age during the two seasons; Kamel et al. (2000) who indicated that B. tabaci infest cantaloupe summer plantation whereas peak occurred during the 4 th week of May, 3 rd week of June and 3 rd week of July during 1995 and 1996 growing seasons; El-Khayat et al.

Nili Plantation:
As shown in Table (

IV-Onion Thrips, T. tabaci (Lind.)
Data obtained in Table (5) cleared that the infestation of thrips on squash plantations (winter, summer and nili) during two successive seasons 2018 and 2019.

Winter Plantation:
As shown in Table (5), the infestation of T. tabaci to squash plants started from 1 st week of February and continued until the 4 th week of April during two successive seasons. Also, the highest average numbers of thrips were recorded on squash plants occurred on 1 st and 2 nd weeks of March (24.67 and 28.00) during 2018 and 2019 growing seasons, respectively, and the highest average numbers monthly of onion thrips were 67.01 recorded during March followed by 30.00 in February and 21.00 in April; and 76.33 recorded during March followed by 39.01 in February and 28.01 in April during 2018 and 2019 growing seasons, respectively.

2-Summer Plantation:
The infestation of onion thrips to squash plants started from the 1 st and 2 nd weeks of June and continued until the 4 th week of August during 2018 and 2019 seasons, respectively. Also, the highest average numbers monthly of T. tabaci were 92.67 recorded during July followed by 42.67 in June and 26.00 in August; and 102.67 recorded in July followed by 53.33 in June and 34.00 in August during 2018 and 2019 successive seasons, respectively. The highest average numbers of thrips recorded on squash plants occurred on the 1 st and 2 nd weeks of July (33.67 and 36.00) during 2018 and 2019 growing seasons, respectively.

3-Nili Plantation:
The infestation of T. tabaci to squash plants started from the 1 st and 2 nd weeks of October and continued until the 4 th week of December during 2018 and 2019 seasons, respectively. Also, the highest average number of thrips was recorded on squash plants that occurred in the 3 rd and 2 nd weeks of October (26.00 and 29.00) during 2018 and 2019 growing seasons, respectively. The highest average numbers monthly of onion thrips were 72.66 recorded during October followed by 37.33 in November and 17.34 in December; and 84.67 recorded during October followed by 44.67 in November and 26.01 in December during growing seasons, 2018 and 2019 respectively. Similar results were obtained by some investigators such as, Metwally et al. (1995) recorded that the T. tabaci started to infest summer squash more early when the plants reached two weeks in age during 1991 and 1992 growing seasons; Kamel et al. (2000) who revealed that, three peaks of thrips were recorded by late May-early June, the 2 nd half of June and 2 nd half of June and 2 nd & 3 rd weeks of July on squash summer plantation during 1995 and 1996 successive seasons; Meligi (2009)  It could be concluded from the previously obtained results, the highest general mean numbers of T. tabaci recorded on squash plants were (161.34 and 190.00) in summer plantation followed by (127.33 and 155.35) in nili plantation and (118.01 and 143.35) in winter plantation.

V-The Green Leafhopper, E. decipiens (Paoli):
Data obtained in Table (6) cleared that the infestation of E. decipiens on squash plantations (winter, summer and nili) during 2018 and 2019 successive seasons.

1-Winter Plantation:
The infestation of E. decipiens to squash plants started from 1 st week of February and continued until the 4 th week of April during 2018 and 2019 growing seasons. Regardless of squash plants and season, the highest average numbers of E. decipiens were recorded on squash plants that occurred on the 3 rd and 4 th weeks of March (39.00 and 42.00) during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers monthly of the green leafhopper were 133.01 recorded during March followed by 79.33 in April and 34.34 in February; and 145.00 recorded during March followed by 90.34 in April and 42.00 in February during 2018 and 2019 seasons, respectively.

2-Summer Plantation:
The infestation of E. decipiens to squash plants started from the 1 st and 2 nd weeks of June and continued until the 4 th week of August during 2018 and 2019 successive seasons, respectively. Also, the highest average numbers monthly of E. decipiens were 171.68 recorded during July followed by 89.67 in August and 46.34 in June; and 184.67 recorded during July followed by 118.33 in August and 56.67 in June during 2018 and 2019 successive seasons, respectively. The highest average numbers of the leafhopper recorded on squash plants occurred in the 3 rd and 4 th weeks of July (53.67 and 56.67) during the 2018 and 2019 growing seasons, respectively.

3-Nili Plantation:
As shown in Table (6), the infestation of E. decipiens to squash plants started from the 1 st and 2 nd weeks of October and continued until the 4 th week of December during 2018 and 2019 growing seasons, respectively. Also, the highest average numbers of the green leafhopper were recorded on squash plants occurred on 3 rd and 2 nd weeks of October (40.67 and 43.00) during 2018 and 2019 growing seasons, respectively, and the highest average numbers monthly of E. decipiens were 146.67 recorded during October followed by 93.67 in November and 28.66 in December; and 156.00 recorded during October followed by 106.00 in November and 37.00 in December during 2018 and 2019 successive seasons, respectively. The present results are in harmony with those obtained by, Metwally et al. (1995) stated that the initial appearance of the green leafhopper, E. decipiens varied from one year first and second seasons, 1991 and 1992 on squash plants, the seasonal activity of jassid was restricted in the second half of summer squash growing season of 1992; Abdalla & Al-Habashy (2013) who indicated that, one peak occurred at the 2 nd week of March for jassid on the broad bean during 2011 and 2012 seasons; Awadalla et al. (2018) who stated that the highest relative abundance of E. decipiens occurred in March plantation on squash plants during 2014 and 2015 successive seasons, and Ismail (2018) who revealed that the jassid E. lybica peaked in the 3 rd week of July, 4 th week of August and 2 nd week of September during 2015 growing season, while in the season of 2016 it peaked in the 2 nd week of August and 1 st week of September occurred on okra plants.
It could be concluded from the aforementioned results, the highest general mean numbers of E. decipiens recorded on squash plants were (307.69 and 359.67) in summer plantation followed by (269.00 and 299.00) in nili plantation and (246.68 and 277.34) in winter plantation.
All in all, in the two seasons of study, the highest infestation with whitefly for winter, summer, and nili squash plantations ranked first followed by the mite, green leafhopper, aphid, and thirps. Also, the summer plantation had the highest population density of the previous main pests followed by nili and winter plantations during two seasons of the study. Therefore, severe injury of the previous main pests to squash plants can be avoided by using the winter plantation followed by nili and summer plantation.