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Dactylopius opuntiae (Cockerell) is one of the major pests of Opuntia ficus-indica in different parts of the world. This research was conducted to study the biology of the insect on Indian prickly pear. The work was carried out in the 2021 season, samples were collected from Qatana city, and insect biology was studied at the Center for Biocontrol Studies and Research at the Faculty of Agriculture, Damascus University in a rearing room under controlled atmospheric conditions (temperature 25±1°C, relative humidity 45±10%). Egg incubation period was evaluated on 100 eggs, life cycle on 150 individuals, and fecundity was determined on 40 females, and the study was conducted using a randomized design. The egg incubation period ranged from 18-27 minutes, with an average of 20.76±0.77 minutes, the first nymphal period 11-14 days, with an average of 12.66±0.53 days for females and 12-16 days with an average of 14.03±0.62 days for males, and the second nymphal period 18-30 days, with an average of 25.16±2.42 days for females and 6-14 days with an average of 8.72±1.67 days for males. The pre-maiden and maiden stage in males lasted 9-16 days with an average of 12.9±1.63 days, and the duration of one generation from egg-laying to full insect emergence ranged from 73-95 days with an average of 85.85±2.09 for females, and 35-68 days with an average of 56.68±0.98 for males. Fertility ranged from 187-266 eggs/female, and the daily egg-laying rate/female ranged from 14-20 eggs/female, with an average of 17.9±0.63 eggs/female/day. Maximum daily fecundity ranged from 13-20 eggs, with an average of 16.6±0.35, and the percentage of hatching ranged from 64-93%, with an average of 87.86±3.92%. The percentage of egg mortality ranged from 17-25%, and in the crawler stage from 18-26%. Alcoholic and aqueous extracts of tobacco (Nicotiana tabacum L.), eucalyptus (Eucalyptus camaldulensis D.), azedarach (Melia azedarach L.) leaves and amaranth (Tagetes patula L.) aerial parts were evaluated in the control of scarlet scale insect (Dactylopius opuntiae Cockerell: Hemiptera, Dactylopiidae) stages in Department of Plant Protection at Damascus University and the field of Qatana city in 2022. It was compared with insecticides (Chlorpyrifos, dimethoate, Lamda-cyhalothrin) and Sycrol mineral oil. The results showed that the aqueous extracts of the tested plants at concentrations of 2.5 and 5% had moderate to low efficacy against D. opuntiae stages. Alcoholic extracts at 5% concentration gave high efficacy on males and nymphs of the insect and the efficacy increased with time after treatment. The average efficacy percentages of tobacco, azedarach, marigold and eucalyptus leaves were 51.18, 46.25, 39.65 and 32.50% for males and 38.25, 27.15, 25.21 and 20.32% for nymphs after 5 days of spraying, respectively. Alcoholic extracts were moderately effective on female insects. On the other hand, Dimethoate and Chlorpyrifos were the most effective pesticides on males, nymphs and adult females of the cochineal scale insect, with significant differences between treatments. Lamda-cyhalothrin and mineral oil were moderately effective on the insect stages. The results also showed that the percentage of efficacy gradually increased with increasing concentration and exposure time. Therefore, alcoholic extracts of tobacco and azedarach can be used in the control of cochineal insect as natural pesticides. Two species of the genus (Dactylopius opuntiae and Dactylopius coccus) are found in the southern region of Syria. D.opuntiae was the most widespread and most capable of capable of spreading and causing infection. No biological enemy was recorded on the insect during the study period. Statistical analysis of the correlation coefficient between weather factors (temperature and relative humidity) severity of infection and the number of females in the colony showed a moderate to strong positive correlation. In the laboratory experiment to test the efficiency of the predator Coccinella septempunctata, no activity was recorded on the D. opuntiae during the trial period.
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