Biological features and population growth of two Southeastern European Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) strains

A study of the biological features and the potential population growth between two laboratory strains of the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) from Greece and Serbia is conducted on cracked barley and cracked white rice. The results show that, at a species level, T. confusum is able to complete development on cracked barley but not on cracked white rice. Therefore, cracked white rice proves to be an unsuitable commodity for T. confusum. Larval development on cracked barley is significantly shorter for the Serbian compared to the Greek strain (37.7 and 49.7 days, respectively), but pupal development does not differ between the two strains (6.2 days for both strains). Additionally, male longevity does not differ between the Greek and Serbian strains (144.4 and 151.4 days, respectively), while female longevity is significantly shorter for the Serbian (151.7 days) compared to the Greek strain (186.6 days). Fecundity does not differ between the two strains (11.3 and 17.7 eggs/female for the Greek and the Serbian strain, respectively), whilst survival is higher for the Serbian strain on both tested commodities. The values of the net reproductive rate, the intrinsic rate of increase and the finite rate of increase on cracked barley are significantly higher for the Serbian (7.27 females/female, 0.025 female/female/day and 1.026, respectively) compared to the Greek strain (2.91 females/female, 0.014 females/female/day and 1.014, respectively). It therefore is expected that different strains of T. confusum may exhibit variable phenology as well as potential population growth. Additionally, we expect our results to have bearing on the management of this species

Study of the biology and management of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) through demographic approach

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is a serious pest of stored products. The effect of temperature on the development and survival of this species was determined at five constant temperatures (20, 25, 30, 32.5 and 35 °C) in the laboratory. Results showed a temperature dependent development of T. castaneum. Data were fitted to the nonlinear Briere model, which for the total immature period estimated the lower threshold at 20.2 °C, the upper developmental threshold at 35.3 °C, and the temperature for maximum developmental rate at 31.2 °C. The Ikemoto and Takai linear model indicated that 659.7 degree-days above a threshold of 16.9 °C were needed to complete immature development from egg to adult emergence. Survival of immature stages varied significantly across temperatures and was well described by an extreme-value function. The model indicated that the highest survival (73.0%) was estimated to occur at 27.4 °C. The curve shows a skewed bell shape, indicating that survival decreases at both ends of the temperature range. Furthermore, there are no data on comparative demographic parameters (i.e., net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time and doubling time) in different temperatures, parameters that allow the in-depth exploration of its survival, mortality and reproduction patterns. Thus, the egg-to-adult development, adult mortality and female fecundity on white soft wheat flour were evaluated at 20, 25, 30 and 32.5 °C. The net reproductive rate increased from 0.08 females/female at 20 °C to 11.77 females/female at 25 °C and 102.07 females/female at 30 °C, followed by a decrease to 10.73 females/female at 32.5 °C. The lowest values of the intrinsic rate of increase and the finite rate of increase were observed at 20 °C (- 0.0105 females/female/day and 0.9895, respectively) and the highest at 30 °C (0.0348 females/female/day and 1.0354, respectively). While the mean generation time did not differ significantly between 20 and 25 °C (249.9 and 225.5 days, respectively), this decreased to 132.8 and 115.1 days at 30 and 32.5 °C, respectively. The value of the doubling time was negative at 20 °C (- 67.5 days), increased to 19.9, 34.0 and 63.9 days at 30, 32.5 and 25 °C, respectively. Using the non-linear Briere model, the lower threshold for T. castaneum population increase was estimated to be 22.2 °C, the upper threshold at 33.2 °C, and the temperature for maximum growth rate was 30.1 °C. Survival analysis indicated that temperature also affected the mortality risk of T. castaneum. The mean survival time increased from 112.1 days at 20 °C to 462.4 days at 25 °C, followed by a decrease to 206.5 and 64.5 days at 30 and 32.5 °C, respectively. The suitability of semolina, cracked wheat and cracked maize as feeding commodities of T. castaneum was investigated. The pest completed its development on all tested commodities. The developmental time of larvae was lower on cracked wheat (59.6 days) and cracked maize (54.6 days) compared to semolina (72.8 days). The developmental time of pupae did not differ significantly among tested commodities, ranging from 6.2 to 6.6 days. Female and male longevities were 70.9 and 77.1 days, 92.2 and 77.9 days and 177.0 and 183.7 days, when T. castaneum was fed on semolina, cracked wheat and cracked maize, respectively. The highest fecundity (28.7 eggs/female) was recorded when T. castaneum was fed on semolina, followed by cracked wheat (2.7 eggs/female) and cracked maize (1.2 eggs/female). The prolonged adult longevity, which was observed on cracked maize, may be attributed to the absence of the cost of reproduction, due to low fecundity on this commodity. The values of the intrinsic rate of increase were 0.014 and -0.021 females/female/day when it was fed on semolina and cracked wheat, respectively, while no demographic analysis was carried out for cracked maize due to high early larval mortality and low fecundity on this commodity. The net reproductive rate and mean generation time were 6.19 females/female and 127.5 days and 0.16 females/female and 91.9 days, when it was fed on semolina and cracked wheat, respectively. Based on demographic analysis, T. castaneum population growth is favored only on semolina. We expect semolina to act as a suitable commodity for T. castaneum, while cracked wheat and cracked maize allow only its survival by acting as alternative commodities. Insecticidal treatment is a common practice for the control of stored-product insect pests. Most studies are focused on the direct effects of insecticides on target insects, while there are no data on the indirect effects on adults in terms of progeny fitness. Consequently, it was needed to investigate the effect of pirimiphos-methyl on adults of T. castaneum and their exposure time cost to progeny fitness. For this purpose, females of T. castaneum were exposed for 1, 3, 8, 16, 24, and 72 h to pirimiphos-methyl and progeny birth or death rates were calculated. The fecundity, as well as the survival of progeny, was affected by the parental exposure to the insecticide. When females were exposed for 1 and 3 h to pirimiphos-methyl, the net reproductive rate of the progeny was 4.1 and 4.3 females/female, respectively, which did not statistically differ with the progeny in control treatment (6.3 females/female). Further exposure time to pirimiphos-methyl affected significantly the progeny net reproductive rate, where the lowest value was observed at the 72-h exposure time (0.97 females/female). The intrinsic rate of increase, as well as the finite rate of increase, did not differ between the progeny of the control treatment (0.029 females/female/day and 1.029, respectively) and the progeny of exposed females at 1 h (0.021 females/female/day and 1.021, respectively) or 3 h (0.023 females/female/day and 1.023, respectively). By increasing the time of exposure to pirimiphos-methyl, a detrimental effect to progeny fitness was revealed based on the values of the intrinsic and finite rate of increase. The lowest values of these parameters were observed at the 72-h exposure time (0.001 females/female/day and 1.000, respectively). The same trend was observed in the values of the doubling time. In contrast, the mean generation time did not statistically differ between control and all insecticide treatments. The fact that the exposure of parental females of T. castaneum to pirimiphos-methyl negatively affects the demographic parameters of their offspring production should be taken into account when management strategies are applied against this notorious stored-product insect species, since it could reduce the repeatedly insecticidal applications in storage facilities.Similarly, there are no data either on the effects of insecticides on the population fitness of T. castaneum. The effect of chlorfenapyr on T. castaneum was investigated in terms of the cost of exposure at different developmental stages on population performance, by using life table statistics and a survival analysis method. For this purpose, eggs, larvae, and parental adult females of T. castaneum were exposed to chlorfenapyr and birth or death rates were calculated daily. The exposure of eggs and larvae to chlorfenapyr was detrimental for T. castaneum and they did not complete development. When parental females were exposed to chlorfenapyr, the progeny survival curve, biological features, as well as the life table parameters did not differ significantly compared to the control treatment. Thus, egg hatching, larval and pupal developmental periods, female and male longevities for the control treatment, and the progeny of the females that were exposed to chlorfenapyr were 4.66 and 4.76 days, 25.85 and 25.71 days, 5.00 and 5.26 days, 87.33 and 104.22 days, and 76.87 and 91.87 days, respectively. In addition, the mean values of the net reproductive rate, the intrinsic rate of increase, the mean generation time and the doubling time for the control treatment and the progeny of the parental females, which were exposed to chlorfenapyr, were 14.3 and 9.3 females/female, 0.038 and 0.028 females/female/day, 1.039 and 1.029, 70.0 and 76.9 days, and 18.5 and 24.9 days, respectively. While the direct effects of several pesticides have been evaluated on T. castaneum, little is known on their indirect effects in terms of progeny fitness. In the sixth experimental series of tests, we investigated the cost of different exposure intervals of T. castaneum females to spinosad by calculating the life table parameters of its progeny. For this purpose, females of T. castaneum were exposed for 5, 10 and 20 min to spinosad and birth or death rates of progeny were estimated. Water was used as a control treatment. The mean values of the net reproductive rate, the intrinsic rate of increase, the finite rate of increase, the mean generation time and the doubling time of the control treatment were 6.3 females/female, 0.029 females/female/day, 1.029, 63.6 days and 24.1 days, respectively, which are indicative of the potential population increase of T. castaneum. When female parental time exposure to spinosad was 5, 10 and 20 min, the corresponding values were 0.073, 0.135 and 0.097 females/female; -0.045, -0.031 and -0.048 females/female/day; 0.956, 0.970 and 0.953; 60.6, 67.7; and 50.3 days; -15.9, -23.3 and -14.8 days, respectively, which indicate a population decrease. However, based on the 95% confidence intervals criterion, the different exposure intervals of T. castaneum females to spinosad did not affect the fitness of their progeny.Το κόκκινο σκαθάρι των αλεύρων, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) είναι ένας σοβαρός εχθρός των αποθηκευμένων προϊόντων. Η επίδραση της θερμοκρασίας στην ανάπτυξη και την επιβίωση του εντόμου προσδιορίστηκε σε πέντε σταθερές θερμοκρασίες (20, 25, 30, 32,5 και 35 °C) εργαστηριακώς. Τα αποτελέσματα έδειξαν ότι η ανάπτυξη του T. castaneum εξαρτάται από τη θερμοκρασία. Τα δεδομένα προσαρμόστηκαν στο μη γραμμικό μοντέλο Briere, το οποίο υπολόγισε για τη συνολική περίοδο της εμφάνισης των ατελών σταδίων το κατώτερο αναπτυξιακό όριο στους 20,2 °C, το ανώτερο αναπτυξιακό όριο στους 35,3 °C και τη θερμοκρασία για τον μέγιστο ρυθμό ανάπτυξης στους 31,2 °C. Το γραμμικό μοντέλο Ikemoto και Takai έδειξε ότι χρειάζονταν 659,7 βαθμο-ημέρες πάνω από το όριο των 16,9 °C ώστε να ολοκληρωθεί η ανάπτυξη από το ωό έως την εμφάνιση των τελείων ατόμων. Η επιβίωση των ατελών σταδίων διέφερε σημαντικά μεταξύ των θερμοκρασιών και περιγράφηκε επαρκώς από μια συνάρτηση ακραίας τιμής. Το πρότυπο έδειξε ότι η υψηλότερη επιβίωση (73,0%) υπολογίστηκε στους 27,4 °C. Η καμπύλη δείχνει ένα λοξό κωδονοειδές σχήμα, υποδεικνύοντας ότι η επιβίωση μειώνεται στα δύο άκρα του εύρους της θερμοκρασίας.Επιπλέον μελέτη σχετικά με την επίδραση της θερμοκρασίας στο T. castaneum πραγματοποιήθηκε γνωρίζοντας πως δεν υπάρχουν συγκριτικά στοιχεία για τις δημογραφικές παραμέτρους (δηλαδή τον καθαρό αναπαραγωγικό ρυθμό, τον ενδογενή ρυθμό αύξησης, τον πεπερασμένο ρυθμό αύξησης, τη μέση διάρκεια γενεάς και τον χρόνο διπλασιασμού), οι οποίες επιτρέπουν την εις βάθος διερεύνηση της επιβίωσης του είδους καθώς και τα χαρακτηριστικά της θνησιμότητας και της αναπαραγωγής του. Έτσι, η ανάπτυξη από το ωό στο τέλειο άτομο, η θνησιμότητα των τελείων ατόμων και η γονιμότητα των θηλέων αξιολογήθηκαν στους 20, 25, 30 και 32,5 °C σε αλεύρι λευκού μαλακού σίτου. Ο καθαρός αναπαραγωγικός ρυθμός αυξήθηκε από 0,08 θήλεα/θήλυ στους 20 °C σε 11,77 θήλεα/θήλυ στους 25 °C και 102,07 θήλεα/θήλυ στους 30 °C, ακολουθούμενο από μείωση σε 10,73 θήλεα/θήλυ στους 32,5 °C. Οι χαμηλότερες τιμές του ενδογενούς ρυθμού αύξησης και του πεπερασμένου ρυθμού αύξησης παρατηρήθηκαν στους 20 °C (- 0,0105 θήλεα/θήλυ/ημέρα και 0,9895, αντιστοίχως) και οι υψηλότερες στους 30 °C (0,0348 θήλεα/θήλυ/ημέρα και 1,0354, αντιστοίχως). Ενώ η μέση διάρκεια γενεάς δεν διέφερε σημαντικά μεταξύ των 20 και των 25 °C (249,9 και 225,5 ημέρες, αντιστοίχως), μειώθηκε στις 132,8 και τις 115,1 ημέρες στους 30 και τους 32,5 °C, αντιστοίχως. Η τιμή του χρόνου διπλασιασμού ήταν αρνητική στους 20 °C (- 67,5 ημέρες) ενώ αυξήθηκε σε 19,9, 34,0 και 63,9 ημέρες στους 30, 32,5 και 25 °C, αντιστοίχως. Χρησιμοποιώντας το μη γραμμικό μοντέλο Briere, το κατώτερο θερμοκρασιακό όριο για την αύξηση του πληθυσμού του T. castaneum υπολογίστηκε στους 22,2 °C, το ανώτερο όριο στους 33,2 °C και η θερμοκρασία για τον μέγιστο ρυθμό ανάπτυξης παρουσιάστηκε στους 30,1 °C. Η ανάλυση επιβίωσης έδειξε ότι η θερμοκρασία επηρέασε επίσης τον κίνδυνο θνησιμότητας του T. castaneum. Ο μέσος χρόνος επιβίωσης αυξήθηκε από 112,1 ημέρες στους 20 °C σε 462,4 ημέρες στους 25 °C, ακολουθούμενος από μείωση σε 206,5 και 64,5 ημέρες στους 30 και 32,5 °C, αντιστοίχως.Στην επόμενη μελέτη διερευνήθηκε η καταλληλότητα του σιμιγδαλιού, του σπασμένου σίτου και του σπασμένου αραβοσίτου ως τροφές για την ανάπτυξη του T. castaneum. Το έντομο ολοκλήρωσε την ανάπτυξή του σε όλες τις εξετασθείσες τροφές. Ο χρόνος ανάπτυξης των προνυμφών ήταν χαμηλότερος στο σπασμένο σιτάρι (59,6 ημέρες) και τον σπασμένο αραβόσιτο (54,6 ημέρες) σε σύγκριση με το σιμιγδάλι (72,8 ημέρες). Ο χρόνος ανάπτυξης των νυμφών δεν διέφερε σημαντικά μεταξύ των εξετασθεισών τροφών, παρουσιάζοντας τιμές που κυμαίνονταν από 6,2 έως 6,6 ημέρες. Η διάρκεια ζωής των θηλέων και των αρρένων ατόμων ήταν 70,9 και 77,1 ημέρες, 92,2 και 77,9 ημέρες και 177,0 και 183,7 ημέρες, όταν το T. castaneum εξετράφη με το σιμιγδάλι, τον σπασμένο σιτάρι και τον σπασμένο αραβόσιτο, αντιστοίχως. Η υψηλότερη γονιμότητα (28,7 ωά/θήλυ) καταγράφηκε όταν το T. castaneum εξετράφη με το σιμιγδάλι, ακολουθούμενο από τον σπασμένο σιτάρι (2,7 ωά/θήλυ) και τον σπασμένο αραβόσιτο (1,2 ωά/θήλυ). Η παρατεταμένη διάρκεια ζωής των τελείων ατόμων η οποία παρατηρήθηκε στον σπασμένο αραβόσιτο μπορεί να αποδοθεί στην απουσία της επιβάρυνσης της αναπαραγωγής λόγω της χαμηλής γονιμότητας σε τούτο το προϊόν. Οι τιμές του ενδογενούς ρυθμού αύξησης ήταν 0,014 και -0,021 θήλεα/θήλυ/ημέρα όταν η διατροφή εγένετο με σιμιγδάλι και σπασμένο σιτάρι, αντιστοίχως, ενώ δεν πραγματοποιήθηκε δημογραφική ανάλυση για τον σπασμένο αραβόσιτο λόγω της υψηλής πρώιμης θνησιμότητας των προνυμφών και της χαμηλής γονιμότητας. Ο καθαρός αναπαραγωγικός ρυθμός και η μέση διάρκεια γενεάς ήταν 6,19 θήλεα/θήλυ και 127,5 ημέρες και 0,16 θήλεα/θήλυ και 91,9 ημέρες, όταν εξετράφησαν με το σιμιγδάλι και το σπασμένο σιτάρι, αντιστοίχως. Με βάση τη δημογραφική ανάλυση, η αύξηση του πληθυσμού του T. castaneum ευνοείται μόνο στο σιμιγδάλι. Αναμένεται ότι το σιμιγδάλι θα λειτουργήσει ως κατάλληλο προϊόν για το T. castaneum, ενώ το σπασμένο σιτάρι και ο σπασμένος αραβόσιτος επιτρέπουν μόνο την επιβίωσή του ενεργώντας ως εναλλακτικά προϊόντα.Οι επεμβάσεις με εντομοκτόνα σκευάσματα είναι μια κοινή πρακτική για τον έλεγχο των εχθρών των αποθηκευμένων προϊόντων. Οι περισσότερες μελέτες επικεντρώνονται στις άμεσες επιδράσεις των εντομοκτόνων στα έντομα στόχους ενώ δεν υπάρχουν δεδομένα για τις έμμεσες επιδράσεις στα τέλεια άτομα όσον αφορά την φυσική κατάσταση των απογόνων τους. Κατά συνέπεια, διερευνήθηκε η επίδραση του pirimiphos-methyl σε τέλεια άτομα T. castaneum και το κόστος του χρόνου έκθεσής τους στην φυσική κατάσταση των απογόνων τους. Για το σκοπό αυτό, τα θηλυκά τέλεια άτομα του T. castaneum εξετέθησαν για 1, 3, 8, 16, 24 και 72 ώρες στο pirimiphos-methyl και υπολογίστηκαν τα ποσοστά γέννησης ή θνησιμότητας των απογόνων τους. Η γονιμότητα και η επιβίωση των απογόνων τους επηρεάστηκε από την έκθεση των μητρικών ατόμων στο εντομοκτόνο. Όταν τα μητρικά άτομα εξετέθησαν επί 1 και 3 ώρες στο pirimiphos-methyl, ο καθαρός αναπαραγωγικός ρυθμός των απογόνων τους ήταν 4,1 και 4,3 θήλεα/θήλυ, αντιστοίχως ενώ δε διέφεραν σημαντικά σε σχέση με τους απογόνους του μάρτυρα (6,3 θήλεα/θήλυ). Ο περαιτέρω χρόνος έκθεσης στο pirimiphos-methyl επηρέασε σημαντικά τον καθαρό αναπαραγωγικό ρυθμό των απογόνων όπου η χαμηλότερη τιμή παρατηρήθηκε στο χρόνο έκθεσης των 72 ωρών (0,97 θήλεα/θήλυ). Ο ενδογενής ρυθμός αύξησης και ο πεπερασμένος ρυθμός αύξησης δεν διέφεραν σημαντικά μεταξύ των απογόνων του μάρτυρα (0,029 θήλεα/θήλυ/ημέρα και 1,029, αντιστοίχως) και των απογόνων των εκτεθέντων θηλυκών ατόμων επί 1 ώρα (0,021 θήλεα/θήλυ/ημέρα και 1,021, αντιστοίχως) ή 3 ώρες (0,023 θήλεα/θήλυ/ημέρα και 1,023, αντιστοίχως). Με την αύξηση του χρόνου έκθεσης στο pirimiphos-methyl παρατηρήθηκε επιζήμια επίδραση στην φυσική κατάσταση των απογόνων με βάση τις τιμές του ενδογενούς ρυθμού αύξησης και του πεπερασμένου ρυθμού αύξησης. Οι χαμηλότερες τιμές των παραμέτρων παρατηρήθηκαν στο χρόνο έκθεσης των 72 ωρών (0,001 θήλεα/θήλυ/ημέρα και 1,000, αντιστοίχως). Η ίδια τάση παρατηρήθηκε στις τιμές του χρόνου διπλασιασμού. Αντίθετα, η μέση διάρκεια γενεάς δεν διέφερε σημαντικά μεταξύ του μαρτύρα και όλων των εκθέσεων. Το γεγονός ότι η έκθεση των τελείων θηλυκών ατόμων T. castaneum στο pirimiphos-methyl επηρεάζει αρνητικά τις δημογραφικές παραμέτρους της παραγωγής των απογόνων τους θα πρέπει να λαμβάνεται υπ’ όψιν όταν εφαρμόζονται στρατηγικές διαχείρισης ενάντια στο T. castaneum καθώς θα μπορούσε να μειώσει τις επαναλαμβανόμενες εντομοκτόνες εφαρμογές στις εγκαταστάσεις αποθήκευσης.Ομοίως, δεν υπάρχουν δεδομένα για τις επιπτώσεις των εντομοκτόνων στην φυσική κατάσταση του πληθυσμού του T. castaneum. Η επίδραση του chlorfenapyr στο T. castaneum διερευνήθηκε ως προς το κόστος της έκθεσης των διαφορετικών αναπτυξιακών σταδίων του στην φυσική κατάσταση του πληθυσμού του χρησιμοποιώντας τον πίνακα ζωής και την μέθοδο ανάλυσης επιβίωσης. Για το σκοπό αυτό, τα ωά, οι προνύμφες και τα γονικά τέλεια θηλυκά άτομα του T. castaneum εξετέθησαν στο chlorfenapyr με τα ποσοστά των γεννήσεων ή του θανάτου τους να υπολογίζονται καθημερινώς. Η έκθεση των ωών και των προνυμφών στο chlorfenapyr ήταν επιζήμια για το T. castaneum και δεν ολοκληρώθηκε η ανάπτυξή τους. Όταν τα θηλυκά τέλεια άτομα εξετέθησαν στο chlorfenapyr, η καμπύλη επιβίωσης των απογόνων τους, τα βιολογικά χαρακτηριστικά τους και οι παράμετροι του πίνακα ζωής δεν διέφεραν σημαντικά σε σύγκριση με τον μάρτυρα. Έτσι, οι περίοδοι ανάπτυξης των ωών, των προνυμφών και των νυμφών, η διάρκεια της ζωής των θήλεων και των αρρένων για τον μάρτυρα και οι απόγονοι των θηλέων ατόμων τα οποία εξετέθησαν στο chlorfenapyr ήταν 4,66 και 4,76 ημέρες, 25,85 και 25,71 ημέρες, 5,00 και 5,26 ημέρες, 87,33 και 104,22 ημέρες, και 76,87 και 91,87 ημέρες, αντιστοίχως. Επιπλέον, οι μέσες τιμές του καθαρού αναπαραγωγικού ρυθμού, του ενδογενούς ρυθμού αύξησης, της μέσης διάρκειας γενεάς και του χρόνου διπλασιασμού για τον μάρτυρα και τους απογόνους των θηλυκών τελείων ατόμων, τα οποία εξετέθησαν στο chlorfenapyr, ήταν 14,3 και 9,3 θήλεα/θήλυ, 0,038 και 0,028 θήλεα/θήλυ/ημέρα, 1,039 και 1,029, 70,0 και 76,9 ημέρες και 18,5 και 24,9 ημέρες, αντιστοίχως.Όπως προαναφέρθηκε, ενώ οι άμεσες επιδράσεις πολλών φυτοφαρμάκων έχουν αξιολογηθεί κατά του T. castaneum, λίγα είναι γνωστά για τις έμμεσες επιδράσεις τους όσον αφορά την ικανότητα των απογόνων τους. Συνεπώς διερευνήθηκε η επίδραση του spinosad σε διαφορετικά χρονικά διαστήματα έκθεσης των θηλυκών τελείων ατόμων T. castaneum, υπολογίζοντας τις παραμέτρους του πίνακα ζωής των απογόνων τους. Για το σκοπό αυτό, θηλυκά τέλεια άτομα T. castaneum εξετέθησαν επί 5, 10 και 20 λεπτά σε spinosad και υπολογίστηκαν τα ποσοστά γέννησης ή θανάτου των απογόνων τους. Ως μάρτυρας χρησιμοποιήθηκε το ύδωρ. Οι μέσες τιμές του καθαρού αναπαραγωγικού ρυθμού, του ενδογενούς ρυθμούς αύξησης, του πεπερασμένου ρυθμού αύξησης, της μέσης διάρκειας γενεάς και του χρόνου διπλασιασμού του μάρτυρα ήταν 6,3 θήλεα/θήλυ, 0,029 θήλεα/θήλυ/ημέρα, 1,029, 63,6 ημέρες και 24,1 ημέρες, αντιστοίχως, που είναι ενδεικτικά της πιθανής πληθυσμιακής αύξησης του T. castaneum. Όταν η έκθεση των μητρικών ατόμων στο spinosad ήταν 5, 10 και 20 λεπτά, οι αντίστοιχες τιμές ήταν 0,073, 0,135 και 0,097 θήλεα/θήλυ, -0,045, -0,031 και -0,048 θήλεα/θήλυ/ημέρα, 0,956, 0,970 και 0,953, 60,6, 67,7, και 50,3 ημέρες, -15,9, -23,3 και -14,8 ημέρες, αντιστοίχως, υποδηλώνοντας την μείωση του πληθυσμού του εντόμου. Ωστόσο, με βάση το κριτήριο των διαστημάτων εμπιστοσύνης 95%, τα διαφορετικά διαστήματα έκθεσης των θηλυκών ατόμων T. castaneum στο spinosad δεν επηρέασαν την φυσική κατάσταση των απογόνων τους

Suitability of Semolina, Cracked Wheat and Cracked Maize as Feeding Commodities for Tribolium castaneum (Herbst; Coleoptera: Tenebrionidae)

In the current study it was investigated the suitability of semolina, cracked wheat and cracked maize as feeding commodities for the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The pest completed its development on all tested commodities. The developmental time of larvae was lower on cracked wheat (59.6 days) and cracked maize (54.6 days) compared to semolina (72.8 days). The developmental time of pupae did not differ significantly among tested commodities, ranging from 6.2 to 6.6 days. Female and male longevities were 70.9 and 77.1 days, 92.2 and 77.9 days and 177.0 and 183.7 days, when T. castaneum was fed on semolina, cracked wheat and cracked maize, respectively. The highest fecundity (28.7 eggs/female) was recorded when T. castaneum was fed on semolina, followed by cracked wheat (2.7 eggs/female) and cracked maize (1.2 eggs/female). The prolonged adult longevity, which was observed on cracked maize, may be attributed to the absence of the cost of reproduction, due to low fecundity on this commodity. The values of the intrinsic rate of increase were 0.014 and −0.021 females/female/day when it was fed on semolina and cracked wheat, respectively, while no demographic analysis was carried out for cracked maize due to high early larval mortality and low fecundity on this commodity. The net reproductive rate and mean generation time were 6.19 females/female and 127.5 days and 0.16 females/female and 91.9 days, when it was fed on semolina and cracked wheat, respectively. Based on demographic analysis, T. castaneum population growth is favored only on semolina. We expect semolina to act as a suitable commodity for T. castaneum, while cracked wheat and cracked maize allow only its survival by acting as alternative commodities. The estimated demographic parameters of T. castaneum on the tested commodities could be used as a useful tool to predict its population outcome in storage facilities

How Is Fitness of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) Affected When Different Developmental Stages Are Exposed to Chlorfenapyr?

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is an important pest of stored products. Insecticidal treatment is a common practice for the control of this notorious insect pest. Most studies are focused on the immediate and/or delayed mortality effects, while there are no data on the effects of insecticides on the population fitness. This study deals with the effect of chlorfenapyr on T. castaneum, investigating the cost of exposure of different developmental stages on population performance, by using life table statistics and a survival analysis method. For this purpose, eggs, larvae, and parental adult females of T. castaneum were exposed to chlorfenapyr and birth or death rates were calculated daily. The exposure of eggs and larvae to chlorfenapyr was detrimental for T. castaneum and they did not complete development. When parental females were exposed to chlorfenapyr, the progeny survival curve, biological features, as well as the life table parameters did not differ significantly compared to the control treatment. Thus, egg hatching, larval and pupal developmental periods, female and male longevities for the control treatment, and the progeny of the females that were exposed to chlorfenapyr were 4.66 and 4.76 days, 25.85 and 25.71 days, 5.00 and 5.26 days, 87.33 and 104.22 days, and 76.87 and 91.87 days, respectively. In addition, the mean values of the net reproductive rate, the intrinsic rate of increase, the mean generation time and the doubling time for the control treatment and the progeny of the parental females which were exposed to chlorfenapyr were 14.3 and 9.3 females/female, 0.038 and 0.028 females/female/day, 1.039 and 1.029, 70.0 and 76.9 days, and 18.5 and 24.9 days, respectively. We expect these results to have bearing on the management of T. castaneum, since the repeatedly insecticidal applications could be reduced in storage facilities

Impact of temperature on life history of two long-term laboratory strains of Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) from Greece and Serbia

The current study examines the influence of temperature (25, 30 and 32.5 °C), on two laboratory strains of Tribolium confusum Jacquelin du Val, originally collected from Greece and Serbia, in terms of immature development, adult longevity, female fecundity and the resulting demographic parameters. Among the tested temperatures, the slowest development as well as the longest longevity of both males and females, were recorded at 25 °C for both strains. Among the two strains, the Serbian completed quicker the egg to adult development at 25 and 32.5 °C. Both strains had the same immature developmental duration at 30 °C. Male longevity was significantly longer for the Greek strain at 30 °C, compared to the Serbian strain. Both strains showed the highest fecundity at 30 °C. Αt all examined temperatures, the females of Serbian strain laid more eggs compared to the Greek strain. There were no statistically significant differences of the survival time between the two strains at any temperature. The intrinsic and the finite rate of increase at 25 °C, was statistically different between the two strains with 0.008 (females/female/day) and 1.008 for the Greek strain and 0.014 (females/female/day) and 1.014 for the Serbian strain, respectively. Mean generation time as well as doubling time were shorter for the Serbian strain at 25 and 32.5 °C. These results will increase the knowledge about the prediction of the precise population growth and infestation in storage units, and to the successful management of T. confusum

Short- and Long-Term Mortalities of Small and Large Larvae of <i>Alphitobius diaperinus</i> (Panzer) (Coleoptera: Tenebrionidae) on Concrete Surfaces Treated with Three Insecticides: Impact of Food

The lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) is an important stored-product pest for the poultry industry as it is a vector of dangerous pathogens for humans. In the present study, we evaluated the short- and long-term mortalities of small and large larvae of A. diaperinus when they were exposed to concrete-covered Petri dishes treated with etofenprox, deltamethrin, and the combination of piperonyl butoxide+acetamiprid+d-tetramethrin. Small and large larvae were exposed to each insecticide applied on concrete surfaces with or without food. The short-term mortality was recorded after 1 day, 3 days, 5 days, and 7 days, while the long-term mortality was recorded 7 days after the transport of the larvae alive to pesticide-free concrete-covered dishes. Regarding short-term mortality levels, 97.8% and 80.0% of the small and large larvae, that were exposed to etofenprox without food, died after 7 days of exposure, respectively. Concerning deltamethrin, all tested small larvae were killed after 3 days (without food) and 5 days (with food) of exposure. For large larvae, deltamethrin caused 98.9% (with food) and 100.0% (without food) mortality levels after 5 days of exposure. The combination of piperonyl butoxide+acetamiprid+d-tetramethrin caused high mortality levels to small larvae, i.e., 84.4% and 100.0% on dishes with and without food, respectively, but low to moderate mortality levels to large larvae that did not exceed 67.8% after 7 days of exposure. Long-term mortality varied vastly among the tested insecticides. Etofenprox killed 100.0% of the small larvae on concrete without food, but 24.0% of the large larvae exposed to concrete containing food. Deltamethrin did not provide long-term mortality to large larvae when food was present. Piperonyl butoxide+acetamiprid+d-tetramethrin caused mortality rates that overall varied from 33.5% (large larvae on concrete with food) to 85.0% (small larvae on concrete with food). In conclusion, deltamethrin killed almost all exposed larvae at exposures of ≤5 days, regardless of their size and the presence of food on the concrete

Sustainable Grain Protectants: Recruiting Entomopathogenic Nematodes against Stored-Product Coleopterans

Stored-product commodities are attacked by numerous insect species. The adulticidal effects of entomopathogenic nematodes (EPNs) on grains remain uninvestigated. Thus, in the current study, seven doses of the EPNs Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), and Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) were inoculated on wheat kernels against adults of Trogoderma granarium Everts (Coleoptera: Dermestidae), Tenebrio molitor L. (Coleoptera: Tenebrionidae), and Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae). Complete mortality (100.0%) of T. granarium was recorded after exposure for eight days to the highest dose of 50,000 Infective Juveniles/mL (IJs/mL) of all tested EPN species. At the same exposure interval, 62.2%, 85.6%, and 76.7% of T. molitor were killed by 50,000 IJs/mL of H. bacteriophora, S. carpocapsae, and S. feltiae, respectively. The highest mortality of A. diaperinus (11.1%) was documented eight days post-exposure to 50,000 IJs/mL of H. bacteriophora. In general, T. granarium was highly susceptible, followed by T. molitor and A. diaperinus. Concerning EPN species, S. carpocapsae exhibited the highest insecticidal capacity, followed by S. feltiae and H. bacteriophora. Trogoderma granarium and T. molitor can be sufficiently managed by the highest dose of 50,000 IJs/mL of all three EPNs and by S. carpocapsae, respectively. However, A. diaperinus was not affected by any EPNs

Sustainable Grain Protectants: Recruiting Entomopathogenic Nematodes against Stored-Product Coleopterans

Stored-product commodities are attacked by numerous insect species. The adulticidal effects of entomopathogenic nematodes (EPNs) on grains remain uninvestigated. Thus, in the current study, seven doses of the EPNs Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), and Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) were inoculated on wheat kernels against adults of Trogoderma granarium Everts (Coleoptera: Dermestidae), Tenebrio molitor L. (Coleoptera: Tenebrionidae), and Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae). Complete mortality (100.0%) of T. granarium was recorded after exposure for eight days to the highest dose of 50,000 Infective Juveniles/mL (IJs/mL) of all tested EPN species. At the same exposure interval, 62.2%, 85.6%, and 76.7% of T. molitor were killed by 50,000 IJs/mL of H. bacteriophora, S. carpocapsae, and S. feltiae, respectively. The highest mortality of A. diaperinus (11.1%) was documented eight days post-exposure to 50,000 IJs/mL of H. bacteriophora. In general, T. granarium was highly susceptible, followed by T. molitor and A. diaperinus. Concerning EPN species, S. carpocapsae exhibited the highest insecticidal capacity, followed by S. feltiae and H. bacteriophora. Trogoderma granarium and T. molitor can be sufficiently managed by the highest dose of 50,000 IJs/mL of all three EPNs and by S. carpocapsae, respectively. However, A. diaperinus was not affected by any EPNs

Sushi domain-containing protein 4 binds to epithelial growth factor receptor and initiates autophagy in an EGFR phosphorylation independent manner

Abstract Background Sushi domain-containing protein 4 (SUSD4) is a recently discovered protein with unknown cellular functions. We previously revealed that SUSD4 can act as complement inhibitor and as a potential tumor suppressor. Methods In a syngeneic mouse model of breast cancer, tumors expressing SUSD4 had a smaller volume compared with the corresponding mock control tumors. Additionally, data from three different expression databases and online analysis tools confirm that for breast cancer patients, high mRNA expression of SUSD4 in the tumor tissue correlates with a better prognosis. In vitro experiments utilized triple-negative breast cancer cell lines (BT-20 and MDA-MB-468) stably expressing SUSD4. Moreover, we established a cell line based on BT-20 in which the gene for EGFR was knocked out with the CRISPR-Cas9 method. Results We discovered that the Epithelial Growth Factor Receptor (EGFR) interacts with SUSD4. Furthermore, triple-negative breast cancer cell lines stably expressing SUSD4 had higher autophagic flux. The initiation of autophagy required the expression of EGFR but not phosphorylation of the receptor. Expression of SUSD4 in the breast cancer cells led to activation of the tumor suppressor LKB1 and consequently to the activation of AMPKα1. Finally, autophagy was initiated after stimulation of the ULK1, Atg14 and Beclin-1 axis in SUSD4 expressing cells. Conclusions In this study we provide novel insight into the molecular mechanism of action whereby SUSD4 acts as an EGFR inhibitor without affecting the phosphorylation of the receptor and may potentially influence the recycling of EGFR to the plasma membrane