Damage to Vegetables and Management

The tawny and shortwinged mole crickets can be serious pests of vegetable crops at times, due to their herbivorous feeding behavior. Tunneling behavior by these two mole crickets and the southern mole cricket can also cause considerable losses in vegetable production. The mole crickets cause the most severe damage to seedbeds and newly transplanted seedlings. Tunneling through the soil around the plants’ root system desiccates the surrounding soil, and the plants become water stressed and eventually die. The mole crickets that feed do so on the roots. During warm, wet nights they may feed upon the stems and occasionally the leaves at the soil surface. Those crops producing marketable products below ground such as potato and radish are also at risk because mole crickets feed on these plant parts as well. Entire plants have been observed having been pulled beneath the soil surface1. The feeding damage is commonly referred to as cutwormlike, and this damage increases the probability of introducing plant pathogens onto the seedlings2. Many vegetables are susceptible to mole cricket damage. Documented cases include seedlings of cucurbits, tomato, potato, carrot, peanut, eggplant, radish, cabbage and lettuce.

Mole crickets are commonly found around the perimeter of a vegetable field and will migrate into the field as the soil fumigants dissipate off and as the growing season progresses1. Therefore, if a field of young seedlings is adjacent to a field or pasture that is infested with mole crickets it will be largely at risk. Mole crickets can increase populations by directly feeding upon the crop or by feeding on weeds that colonize between the crop rows. Smaller vegetable seedlings appear to be very susceptible to feeding damage and the soil disruption caused by the tunneling activity of the mole crickets. Larger transplants appear to be more tolerant.

Reducing initial mole cricket infestations in the field can be accomplished by applying soil fumigants before or immediately after transplanting. Check the local County Extension Service for the most appropriate and effective fumigant. To decrease the likelihood of substantial damage, transplant large rather than small seedlings, which may be more tolerant to the mole cricket damage. Reducing the occurrence of weeds that may colonize in the field and act as alternate food sources for the mole crickets may also limit population growth.

Biological control is an attractive way to suppress pest mole crickets and has proven successful in Florida. Ormia depleta is a natural enemy of the pest mole crickets and its populations have spread almost everywhere in Florida south of Ocala. Larra bicolor, another natural enemy of the pest mole crickets has populations present in a few counties in northern Florida, but is spreading. With deliberate plantings of food sources for the adults of these two organisms it is likely that their populations can be increased locally, as with butterfly gardening, and effectively reduce pest mole cricket populations.

References

1 Schuster, D.J., Price, J.F. 1992. Seedling Feeding Damage and Preference of Scapteriscus spp. Mole Crickets (Orthoptera: Gryllotalpidae) Associated with Horticultural Crops in West-Central Florida. Fla. Ent. 75: 115-19.

2 Hudson, W.G. 1985. Other behavior, damage, and sampling. In: Walker TJ, editor. Mole Crickets in Florida: Florida Agric. Exp. Bull. 846. p 16-21.


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