Effect of age, female mating status and density on the banana weevil response to aggregation pheromone

Abstract

The banana (Musa spp.) weevil (Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) is a major pest in East Africa causing yield losses of up to 14 metric tonnes per hectare annually. Laboratory and field experiments were conducted to determine whether the response of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) to its aggregation pheromone was influenced by age, female mating status and weevil density. Laboratory bioassays were conducted using a double pitfall olfactometer, while a bucket pitfall trap was used in field experiments. There was no significant (P>0.05) difference in response to pheromone between immature and mature weevils (males and females) in laboratory bioassays. Forty-day-old weevils had a stronger response to the pheromone than 10-day-old ones under field conditions. The response of unmated weevils to the pheromone was stronger than that of mated weevils, both in the laboratory and field. The percentage of unmated and mated weevils recaptured from 0 and 3 m were similar but significantly different from 6 m way from the pheromone baited trap. The response of the weevils to the pheromone was not significantly (P>0.05) influenced by its previous density.

Migration potential of the banana weevil Cosmopolites sordidus

“…There was no significant difference between the number of recaptured males and females in the pheromone trials. The aggregation pheromone sordidin is attractive to both sexes (Budenberg et al , 1993a), although some studies reported that females respond more strongly to sordidin than males (De Graaf et al , 2005; Tinzaara et al , 2005a), whereas others are in line with the present study and recorded no significant difference between the sexes (Jayaraman et al , 1997; Tinzaara et al , 2005b). It has also been suggested that females are more active, move quicker and cover longer distances than males as a result of their 10–20% larger size (Gold et al , 2001).…”

Evidence for the presence of a female produced sex pheromone in the banana weevil Cosmopolites sordidus Germar (Coleoptera: Curculionidae)

“…The male aggregation pheromone of C. sordidus has since been isolated, synthesized and even field-tested (Tinzaara et al, 2011, Alpizar et al, 2012. This synthetic pheromone, named sordidin or Cosmolure+ (depending on manufacturers), have been found to be successful in mass trappings; capturing 18 times more weevils than the conventional pseudostem traps in Uganda (Tinzaara et al, 2011); although Alpizar et al (2012) highlighted a range of 2½ to 8-fold increases under different conditions.…”

Ovarian development in Cosmopolites sordidus Germar (Coleoptera: Curculionidae)

“…mass trapping or even chemical control) to prevent possible outbreaks. [2] reported that capturing unmated and fertile female C. sordidus could play a significant role in slowing down the pest's population build-up. Other benefits may be in varietal screening works as susceptible cultivars would readily support rapid pest growth and developments, whilst resistant varieties lead to possible impairments and arrested developments, such as delays in oocyte emergence, oocyte maturation, and prolonged pre-oviposition periods.…”

“…The banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is a major insect pest of bananas and plantains the world-over; causing considerable reductions in yearly productions of the crop globally [1], [2], [3]. The pest attacks all species of Musa and no cultivar is known to have a total resistance to it; although certain cultivars are now known to be more susceptible to the borer than others [3], [4], [5].…”