Research Update
Understanding the Feeding Ecology of Mole Crickets (ATRF Funded Research)
By Yao Xu and David W. Held, Ph.D., Dept. of Entomology and Plant Pathology, Auburn University
The
tawny mole cricket (TMC), Scapteriscus vicinus, and southern mole cricket (SMC), S. borellii, are among the most significant pests of turfgrass in the southeastern United States. They both occur on golf courses and lawns, causing damage to turfgrass from feeding and tunneling. TMCs are considered primarily herbivores that can cause severe turf loss by directly feeding on the roots, stems and leaves of grass. SMCs, although more abundant in Alabama turf, are primarily carnivores and cause turf injury mainly by tunneling. A novel research project evaluating the feeding ecology of these mole crickets and the associated damage to turfgrass is near completion at Auburn University. The objectives of this project are to determine the dietary choices of mole crickets in laboratory feeding assays and their implications for the growth and development of mole crickets, as well as for damage to bermudagrass.
Al ab ama Tu rf Tim e s > >> Spri ng 2012
Feeding preference and dietary impact on development
Using ground mealworms and organic carrot strips as representative animal and plant diets, respectively, we tested the feeding preference of adult SMCs in laboratory choice and no-choice tests. As an omnivore, both plant and animal diets were acceptable to SMCs in no-choice tests. However, when given a choice, SMCs prefer an animal diet. We tested the nutritional profiles of both diets and found that the dietary choice likely reflects the lower nitrogen content of plant tissue (1% nitrogen) compared with animal tissue (9% nitrogen). Nitrogen is an important nutrient that insects must get from their diet. Conventional mole cricket control mainly depends upon the timing of treatment and the life stages that the pests
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are in at the time. Particularly, an effective treatment should be directed towards the more vulnerable young nymphs. However, it is common to find a wide range of ages of the nymphs in the same area. This situation may be closely related with the feeding habits of mole crickets. We conducted laboratory experiments using SMC nymphs to evaluate how different diet treatments affect the longevity and nymphal development of mole crickets. Our research Every two days, newly hatched nymphs were provided a comparable amount of a plant (organic carrot strips), animal (ground mealworms) or rotational diet (alternating plant and animal diets every two days). Starved nymphs were a negative control (interestingly, nymphs can survive for one month in sand with no food). After three months, SMC nymphs that fed on only plants had the lowest body weight and the longest duration of each instar (time between molts). Nymphs fed the animal diet had the greatest body weight and the fewest days to reach the adult stage. Again, the nutritional value of both diets may explain this variation in development. This is the first choice and developmental study with turf-infesting mole crickets. Since management/control targets nymphs, and diet influences development, diet then influences the age distribution of treated populations. These results reinforce the Extension recommendation to treat populations when small nymphs are present. As populations age, the difference in size may enable some larger individuals to survive a treatment that kills smaller individuals. Similar tests with TMCs will be conducted to compare the two species. Since TMCs are primarily herbivorous, it will provide an interesting comparison to SMCs.