Effects of host plants on distribution, abundance, developmental time and life table parameters of Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae)

The biology and ecology of the date palm mite O. afrasiaticus have been studied through regular inspection in Tunisian oases and laboratory observations. Results indicate that the start date of fruit infestation varied between years and by date palm variety. Start dates ranged from the first week to the third week of July. The period spent by the mite on fruits varied from one variety to another; lasting 8 weeks on the Deglet Noor variety, 2 to 5 weeks on Alig, 2 to 4 weeks on Kentichi dates, and 2 to 4 weeks on Bessr fruits. The Deglet Noor variety was the most susceptible to O. afrasiaticus. Mite populations on the pinnae remained low from May through December. During autumn and spring, O. afrasiaticus was found on sorghum leaves in the orchard ground-cover. A life table study in the laboratory at 27°C on six host plants (fruits of date palms varieties Deglet Noor, Alig, Kentichi, Bessr, and Deglet Noor pinnae and sorghum leaves) showed that the life cycle of O. afrasiaticus differed among host plants with average values ranging between 13 on Alig fruits and 10.9 days on sorghum leaves. Relatively high fecundity was found on sorghum leaves (2 eggs/female/day) during 5.2 oviposition days, while low fecundity values occurred on Deglet Noor pinnae and Alig fruits with 0.7 eggs/female/day during 5.4 days. Average longevity of O. afrasiaticus females ranged from 13.4 to 7.5 days on Deglet Noor fruits and sorghum leaves, respectively. Intrinsic rate of increase (r m) was highest on sorghum leaves (0.171) and Deglet Noor fruits (0.166), and lowest on Alig fruits (0.103). Greater knowledge of life history traits and seasonal abundance of this species is needed in order to design appropriate control strategies.A biologia e ecologia do ácaro da tamareira O. afrasiaticus foram estudadas através de inspeções regulares em oásis Tunisianos e observações em laboratório. Os resultados indicam que a data inicial da infestação dos frutos variou entre os anos e pelo tipo de variedade das tamareiras. Datas iniciais variaram entre a primeira e a terceira semana de julho. O período passado pelo ácaro nos frutos variou de acordo com o tipo de tamareira, sendo de 8 semanas na variedade "Deglet Noor", de 2 a 5 semanas na "Alig", 2 a 4 semanas nas tâmaras "Kentichi", e 2 a 4 semanas nos frutos "Bessr". A variedade "Deglet Noor" foi a mais sensível ao O. afrasiaticus. As Populações de ácaros nas pinhas permaneceram baixas de maio a dezembro. Durante o outono e na primavera, O. afrasiaticus foi encontrado em folhas de sorgo no solo dos pomares. Um estudo tabelado com o ciclo de vida em laboratório, a 27°C, em seis plantas hospedeiras (tâmaras das variedades "Deglet Noor", "Alig", "Kentichi", "Bessr", as pinhas de "Deglet Noor" e folhas de sorgo) mostrou que o ciclo de vida de O. afrasiaticus variou entre as diferentes plantas hospedeiras com valores médios de 13 dias nos frutos Alig e 10,9 dias em folhas de sorgo. Uma fecundidade relativamente alta foi observada em folhas de sorgo (2 ovos/fêmea/dia) durante 5,2 dias de ovipostura, enquanto valores mais baixos de fecundidade foram observados nas pinhas "Deglet Noor" e frutos "Alig" com 0,7 ovos/fêmea/dia durante 5,4 dias. A longevidade média das fêmeas de O. afrasiaticus variou entre 13,4 a 7,5 dias nos frutos "Deglet Noor" e folhas de sorgo, respectivamente. A taxa intrínseca de aumento (r m) foi mais alta em folhas de sorgo (0,171) e frutos "Deglet Noor" (0,166), e mais baixos nos frutos "Alig" (0,103). Um maior conhecimento da história de vida e abundância sazonal desta espécie é necessário para que estratégias apropriadas de controle possam ser elaboradas

Management of Ceratitis capitata (Diptera: Tephritidae) in Tunisian oases by mass trapping methods

In Tunisia oases, the Mediterranean fruit fly (medfly) Ceratitis capitata affect heavily fruit production. The efficiency of the mass trapping technique based on the use of Cera Trap® was evaluated in two types of oases in the south of Tunisia against C.capitata. Our results showed that in the traditional oasis (mixed orchard), the medfly moves from one fruit specie to another according to their receptivity periods. The population density of medflies started low and peaked three times (16 Jun, 23 Jun, and 7 July) corresponding to the maturation period of apricot fig and peach fruits. The field study showed that medfly population density and rate of fruit damage were significantly lower in figs than in peaches and apricot. Modern oases have later apricot fruit maturity periods than traditional oases, and their medfly populations peaked at 19 Mai.  Ceratrap® reduces 2, 2, and 6 times the population density of Mediterranean fruit fly and the rate of damaged fruits  compared to untreated plots. These two parameters were twofold less in modern oases than in traditional oases. These results suggest that the use of traps at the density of 70 per ha is sufficient to protect crops under high population densities of C. capitata characterizing the traditional oases agricultural systems

Comparative Demography of the Spider Mite, Oligonychus afrasiaticus, on four Date Palm Varieties in Southwestern Tunisia

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of palm date fruits. Life cycle, fecundity, and longevity of this mite were studied on fruits of four date palms, Phoenix dactylifera L. (Arecales: Arecaceae)(varieties: Deglet Noor, Alig, Kentichi, and Besser), under laboratory conditions at 27 = 1 °C, 60 ± 10% RH. Total development time of immature female was shorter on Deglet Noor fruits than on the other cultivars. O. afrasiaticus on Deglet Noor had the highest total fecundity per female, while low fecundity values occurred on Besser. The comparison of intrinsic rates of natural increase (rm), net reproductive rates (Ro), and the survival rates of immature stage of O. afrasiaticus on the host plants suggests that O. afrasiaticus performs better on Deglet Noor fruits. The mite feeding on Alig showed the lowest intrinsic rate of natural population increase (rm = 0.103 day 1). The estimation of difference in susceptibility of cultivars to O. afrasiaticus is crucial for developing efficient pest control programs. Indeed, less susceptible cultivars can either be left unsprayed or sprayed at low threshold

Effects of host plants on distribution, abundance, developmental time and life table parameters of Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae)

The biology and ecology of the date palm mite O. afrasiaticus have been studied through regular inspection in Tunisian oases and laboratory observations. Results indicate that the start date of fruit infestation varied between years and by date palm variety. Start dates ranged from the first week to the third week of July. The period spent by the mite on fruits varied from one variety to another; lasting 8 weeks on the Deglet Noor variety, 2 to 5 weeks on Alig, 2 to 4 weeks on Kentichi dates, and 2 to 4 weeks on Bessr fruits. The Deglet Noor variety was the most susceptible to O. afrasiaticus. Mite populations on the pinnae remained low from May through December. During autumn and spring, O. afrasiaticus was found on sorghum leaves in the orchard ground-cover. A life table study in the laboratory at 27°C on six host plants (fruits of date palms varieties Deglet Noor, Alig, Kentichi, Bessr, and Deglet Noor pinnae and sorghum leaves) showed that the life cycle of O. afrasiaticus differed among host plants with average values ranging between 13 on Alig fruits and 10.9 days on sorghum leaves. Relatively high fecundity was found on sorghum leaves (2 eggs/female/day) during 5.2 oviposition days, while low fecundity values occurred on Deglet Noor pinnae and Alig fruits with 0.7 eggs/female/day during 5.4 days. Average longevity of O. afrasiaticus females ranged from 13.4 to 7.5 days on Deglet Noor fruits and sorghum leaves, respectively. Intrinsic rate of increase (r m) was highest on sorghum leaves (0.171) and Deglet Noor fruits (0.166), and lowest on Alig fruits (0.103). Greater knowledge of life history traits and seasonal abundance of this species is needed in order to design appropriate control strategies

The Spatio-Temporal Distribution Patterns of the Spider Mite, Oligonychus afrasiaticus, on Date Palm (Deglet Nour Cultivar) in a Pesticide Free Tunisian Oasis

Seasonal abundance of the date palm spider mite Oligonychus afrasiaticus on date palm (Deglet Nour cultivar), was studied between 2004 and 2006 in a pesticide-free oasis. The objectives of this study were to (i) inventory mite species present around date palm trees, (ii) quantify abundance of O. afrasiaticus in trees and in ground cover and (iii) to monitor O.afrasiaticus population dynamics and its dispersal. The first infestations of O.afrasiaticus on fruits varied between years, ranging from the first to the third week of July. Spider mite density increased rapidly throughout July and August during the fruit’s Kimri stage, characterized by greenness. At the end of August, higher rates of O. afrasiaticus migrated to the palm crown. Overwintering O. afrasiaticus individuals were found on the pinnaes, but no overwintering individuals were found on the ground cover. Phytoseiids were very scarce, only two phytoseiid species were collected on the ground cover. During the years of observation no phytoseiid mites able to reduce the populations of O. afrasiaticus were found on Deglet Nour dates. Pest dispersion starts from a palm tree located at far away from the well of water. Causes of O. afrasiaticus outbreaks on fruits included (1) absence of predators (2) dry weather (3) no application of pesticides that suppress O.afrasiaticus

Management of Ceratitis capitata (Diptera: Tephritidae) in Tunisian oases by mass trapping methods

In Tunisia oases, the Mediterranean fruit fly (medfly) Ceratitis capitata affect heavily fruit production. The efficiency of the mass trapping technique based on the use of Cera Trap® was evaluated in two types of oases in the south of Tunisia against C.capitata. Our results showed that in the traditional oasis (mixed orchard), the medfly moves from one fruit specie to another according to their receptivity periods. The population density of medflies started low and peaked three times (16 Jun, 23 Jun, and 7 July) corresponding to the maturation period of apricot fig and peach fruits. The field study showed that medfly population density and rate of fruit damage were significantly lower in figs than in peaches and apricot. Modern oases have later apricot fruit maturity periods than traditional oases, and their medfly populations peaked at 19 Mai.  Ceratrap® reduces 2, 2, and 6 times the population density of Mediterranean fruit fly and the rate of damaged fruits  compared to untreated plots. These two parameters were twofold less in modern oases than in traditional oases. These results suggest that the use of traps at the density of 70 per ha is sufficient to protect crops under high population densities of C. capitata characterizing the traditional oases agricultural systems

Pancreatic surgery outcomes: multicentre prospective snapshot study in 67 countries

Background: Pancreatic surgery remains associated with high morbidity rates. Although postoperative mortality appears to have improved with specialization, the outcomes reported in the literature reflect the activity of highly specialized centres. The aim of this study was to evaluate the outcomes following pancreatic surgery worldwide.Methods: This was an international, prospective, multicentre, cross-sectional snapshot study of consecutive patients undergoing pancreatic operations worldwide in a 3-month interval in 2021. The primary outcome was postoperative mortality within 90 days of surgery. Multivariable logistic regression was used to explore relationships with Human Development Index (HDI) and other parameters.Results: A total of 4223 patients from 67 countries were analysed. A complication of any severity was detected in 68.7 percent of patients (2901 of 4223). Major complication rates (Clavien-Dindo grade at least IIIa) were 24, 18, and 27 percent, and mortality rates were 10, 5, and 5 per cent in low-to-middle-, high-, and very high-HDI countries respectively. The 90-day postoperative mortality rate was 5.4 per cent (229 of 4223) overall, but was significantly higher in the low-to-middle-HDI group (adjusted OR 2.88, 95 per cent c.i. 1.80 to 4.48). The overall failure-to-rescue rate was 21 percent; however, it was 41 per cent in low-to-middle-compared with 19 per cent in very high-HDI countries.Conclusion: Excess mortality in low-to-middle-HDI countries could be attributable to failure to rescue of patients from severe complications. The authors call for a collaborative response from international and regional associations of pancreatic surgeons to address management related to death from postoperative complications to tackle the global disparities in the outcomes of pancreatic surgery (NCT04652271; ISRCTN95140761)