Monitoring the activity and biology of pest Bruchus rufimanus (Coleoptera: Chrysomelidae) in beans crops

Abstract

The main objective of this study is the Population dynamics evaluation of broad bean bruchid Bruchus rufimanus (Coleoptera: Chrysomelidae) in crops beans of Vicia faba within the El Asnam’s region (Algeria). A weekly monitoring of B. rufimanus was made during breeding diapauses in the laboratory and during their colonization in the parcel of variety of Séville, and then a comparative study had been implemented to characterize the total haemolymphatic protein levels during diapause and the periods of reproductive activity. The obtained results demonstrated that after the diapause period, the colonization of the field by adults of B. rufimanus coincides with the period of full bloom of the host plant which represents a trophic source necessary for the reproductive activity. 54 beetles were captured from which 28 were males. Oviposition covering a period of one month and 15 days, with a total of 168 eggs being counted, of which 72 were placed on the low layer pods. The total hemolymphatic protein content of B. rufimanus was found a high concentration during diapause and varying between 46 to 85.8ìg/ìl. High levels of protein were probably due to the stock of proteins during the larval life of this pest. Protein levels had decreased significantly in April, reflecting a recovery in the activity and colonization of bean fields for food, sexual partnership, spawning, and other activities. However, throughout the month of May, the protein concentration increased due to the pollen supply provided by the host plant and weeds present in the agrosystem.

Optimizing Insecticide Application Timing for Broad Bean Weevil Control and Minimizing Crop Damage in Broad Bean (Vicia faba Linn.)

“…According to Rusch et al [23], local climate conditions affect diapause termination and the emergence time of adults. Arrival of the first B. rufimanus adults at the fields depended on the daily temperature and growth stage of the host plant [24]. The results showed that adult emergence occurred prior to flowering, in line with the work of Ward [12], which reported that the presence of broad bean flowers was not necessary to affect the termination of diapause and adult emergence.…”

“…The results showed that during the pod development stage, the number of B. rufimanus beetles captured in the traps started to decrease to the total absence, which could be due to their dispersal to other sites where the broad bean varieties still had flowers or due to their death after reproduction [26]. Similar results were obtained by Hamani-Aoudjit et al [24], who found that the peak of B. rufimanus beetles occurred at the flowering time, and then started to decrease until complete absence.…”

“…This study showed that B. rufimanus had one generation per year over the study years. In our study, the highest abundance was at the full bloom of the broad bean, and this can be explained by the fact that flowers are considered a trophic substrate for B. rufimanus adults, as Hamani-Aoudjit et al [24] reported. Our results agree with those of Titouhi et al [27], Titouhi et al [28], and Gebremedhin et al [29], who all confirmed that the peak of adult activity coincided with the full flowering stage in the host plants.…”

“…So, the main target of the control is adults because females deposit eggs on the surface of pods [11]. The insecticide sprays should coincide with the egg-laying period to be efficient [24]. The reason why there were no differences between some treatments can be explained by the unsuitable phenological development stage for B. rufimanus females for laying eggs at the time of insecticide spray.…”