Experienced males recognise and avoid mating with non-virgin females in the western flower thrips

Abstract

The western flower thrips Frankliniella occidentalis (Thysanoptera: Thripidae) is a major insect pest on a wide range of crops throughout the world. There are several unexplained aspects of the mating behaviour, particularly in relation to male-male competition and mate choice. The objectives of the study were to test whether males can detect the mating status of females and whether males avoid mating with previously mated females. Experiments involved either ‘experienced’ adults taken from a laboratory culture, which had been exposed to high densities of thrips, or virgin adults reared individually. Experienced males mated readily with virgin females, but avoided mating with experienced females. Virgin males showed much less discrimination between females. Avoidance of mating with experienced females is likely to be widespread because it occurred in populations from both the United Kingdom and Kenya. Experienced males also mated with dead virgin females, but avoided mating with dead experienced females, which ruled out the possibility that behavioural differences between the females were responsible. To test whether males could detect whether or not females had mated, virgin females of the same age from the same cohort were either mated once or not mated. Experienced males mated with the dead females that were virgin and avoided mating with the dead females that differed only in that they had mated once shortly before. This showed that males recognise whether or not a female has mated and avoid mating with previously mated females. This avoidance by males suggests that mated females are not usually subjected to high levels of male harassment. The most likely explanation of the avoidance is that males produce an antiaphrodisiac pheromone that is applied to females during mating.

Mating behaviour, mate choice and female resistance in the bean flower thrips (Megalurothrips sjostedti)

“…Although two components of a male-produced aggregation pheromone, which attracts both males and females, have been identified and investigated with olfactometer experiments 27 , there have been no close-range studies of the mating behaviour. Our pilot observations indicated that there were some distinct and unexpected differences from the behaviour we observed in F. occidentalis 20 , 28 . Males often avoided mating with older virgin females and virgin females often strongly resisted male mating attempts.…”

“…In F. occidentalis , females appear to mate with the first male they encounter and then depart 6 , 14 . In laboratory bioassays, females mated readily with most males 20 , which also suggests that females are not choosing. Terry and Dyreson 14 suggested that male F. occidentalis could be competing for the best sites on flowers, where females are more likely to land, which would mean that females do not need to choose because preselection by the males themselves has occurred prior to female visits.…”

“…However, females typically arrive singly and so for males the choice is usually whether or not to mate rather than a choice between females. In F. occidentalis , males avoid mating with recently mated females 20 , so there is some choice, and this may explain why males ignore some females in aggregations 6 . Evolutionary theory suggests that males should not be choosy, because the benefits of choosiness would not outweigh the costs of lost mating opportunities 22 , 24 and that male mate choice is less likely to evolve when there is sequential choice 22 .…”

Fighting Behaviour of Male Onion Thrips, Thrips tabaci (Thysanoptera: Thripidae) Lineages

“…Furthermore, it has been noted in the Australian field cricket that male dominance status is associated with the expression of male pheromone signals (Thomas and Simmons, 2009). Akinyemi and Kirk (2019) found that an antiaphrodisiac pheromone was produced in F. occidentalis males but not in females. Thus, as L1 and T lineages have substantial variations genetically and in host adaptations, the type and quantity of male-produced pheromones may be varied too, and it may be the reason behind variations in the intensity of male fighting performance observed.…”

Morphology and Distribution of Antennal Sensilla in Three Species of Thripidae (Thysanoptera) Infesting Alfalfa Medicago sativa

“…Similar as many other herbivorous insects, thrips perceive chemical signals of plant volatiles and insect pheromones using their sensory organs for host recognition, feeding, and other life activities such as mating and oviposition [ 7 , 8 , 9 , 10 , 11 ]. For example, western flower thrips, F. occidentalis can be attracted by stereoisomers, a type of volatiles released by their host plants [ 12 ], and they can also react quickly when perceiving alarm pheromones released by other second-instar nymphs [ 13 ].…”