Factors Influencing Mating Behavior and Success in the Red Palm Weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae)

Abstract

The effects of body size, age, feeding and mating status, conspecific volatiles from live adults, synthetic aggregation pheromone, and a pheromone synergist, ethyl acetate, on the mating behavior of red palm weevil, Rhynchophorus ferrugineus Olivier, were investigated. To evaluate these factors, variables such as mating latency, frequency and duration, and refractory period were assessed. While both, body size and age, influenced the mating behavior, the latter showed a stronger effect. The large males recorded frequent and longer matings, whereas the young males outperformed the old weevils in all the studied variables. The difference in body size or age of females showed a limited effect. After 72 h without food, the males showed a significant decline in mating frequency and duration, and refractory period. Mating status showed comparatively stronger effects on mating variables. In the case of females, mating status emerged as the most important factor affecting four out of five variables. The volatiles from the males, grouped males and females, and synthetic aggregation pheromone both alone and in combination with ethyl acetate triggered mating initiation, propelled mating frequency, prolonged total mating duration, and reduced the refractory period. However, the presence of females or ethyl acetate alone was a weak mating stimulator.

Factors Influencing Copulation Duration in Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae)

“…These operations may significantly prolong the copulation duration, thereby allowing much more high-quality offspring to be harvested. In addition, the effects of adult age at mating on the copulation duration were also well documented [10,15]. Conducting a relevant study on the effect of adult age at mating on the copulation duration by this ectoparasitic beetle may be very interesting because the lifespan of this insect lasts more than four years [32].…”

“…Variation in copulation duration is influenced by several physiological and ecological factors [7,45,46]. Many insect species exhibit a positive correlation [12], a differential effect between body size and copulation duration [10,47], or a seasonal dependence, i.e., the copulation duration is positively correlated with body size in the earlier part of the year but negatively correlated with body size in the late part of the year [11]. The results from our present trial suggested that medium-sized individuals copulated significantly longer than did smaller and larger individuals, but no significant effect of sex was observed on the copulation duration of D. helophoroides (Figure 3a).…”

“…Ecological conditions such as access to an adequate and appropriate diet are among the factors that affect insect mating behavior and fitness [24]. Many insects, such as the red flour beetle Tribolium castaneum [55], the red palm weevil Rhynchophorus ferrugineus [10], and the aphidophagous ladybird beetle Propylea dissecta [24], attempt to avoid copulation and even decrease the copulation duration under starvation conditions. However, in some published insects, starvation does not have any meaningful effect on the copulation duration, and the results are not significant, which may indicate that nutritional status is not an important factor affecting mating, such as in the medfly Ceratitis capitata [56] and the aphidophagous ladybird beetle Hippodamia variegata [25].…”

“…A large number of empirical studies have shown that the copulation duration is highly variable between and within insect species [8,9], and how the copulation durations change is a complex and intriguing question. A variety of physiological and ecological factors affect the copulation duration in insects [7,10]. For example, body size plays an important role in driving the copulation duration [11].…”

An Assessment of the Efficacy of Pheromone Traps in Managing the Red Palm Weevil

“…Palm weevils are found in relatively small numbers in most date palm farms and have a longlife span (Abdel-Azim, et al, 2019). These features make it possible for intensive trapping to be an effective control strategy as the trapping of low numbers will have an impact on subsequent populations and a considerable percentage of a weevil population can be caught over a long time period, they are vulnerable to traps baited with the synthetic pheromone and food materials.…”