Why we should use beneficial nematodes to kill dog fleas in fall?

Beneficial nematodes and dog flea, Ctenocephalides canis control

Fleas are small wingless insects that cannot fly but can easily jump on their hosts including cats, dogs, humans and rats (Glazer et al., 2005). Fleas have piercing and sucking type of mouthparts that they use for sucking of blood from their hosts. While feeding on the host blood, fleas can also transmit disease causing organisms to their host and make them sick. Fleas develop through four different developmental stages including eggs, larva, pupa and adult. Fleas lay eggs on host’s body.  These eggs then fall off on the ground where their host usually rests or sleeps during day or night time. Eggs hatch within 1-2 weeks and the hatched larvae begin feeding on only organic matter. These larvae cannot feed on host blood or cause any direct damage to their hosts. Only adult fleas are capable of feeding on the host blood, transmitting diseases and causing direct damage to their hosts. While feeding on the organic matter, larvae develop through three larval stages. The matured larvae then pupate inside the silken cocoons in soil.  Adult fleas generally use cues like carbon dioxide, heat and vibration from their hosts to emerge from cocoons. The emerged adult fleas then hop on the host body whenever their hosts are visiting their resting/ sleeping place. Once on the host body, fleas feed on the host blood, mate and lay eggs. Eggs fall off of host on the ground and life cycle continues.Fleas complete several generations during summer through the fall season and then overwinter as larvae and pupae in the soil mostly at the resting place of their host animals especially dogs.  Generally, declining temperatures during fall season provide an important cue for fleas to get ready for winter weather. Therefore, during fall as temperature begins cooling down most of the larval and pupal population of fleas will remain in the soil throughout the winter and then they will emerge as adults from pupae during spring. Since adult fleas are always hopping on and off their host bodies, they are very difficult to control with either insecticides or biological control agents. In contrast, both larval and pupal stages of fleas are always live in the soil and therefore, they can be easily targeted and killed by using either chemical pesticides or the biological control agents like beneficial entomopathogenic nematodes.

Biological control of dog fleas, Ctenocephalides canis

Chemical pesticides can be effective in killing both the larval and pupal stages of fleas but their use in back yards and around houses is restricted due their detrimental effects on humans, pet animals (cats and dogs) and the environment. Biological control agents such as beneficial entomopathogenic Steinernema carpocapsae nematodes are the best alternatives to chemical pesticides in reducing population of fleas because they are not harmful to humans, pets, wild animals and the environment. Since fleas generally overwinter as larval and pupal stages in the soil, they are easily targeted and killed by applying beneficial entomopathogenic Steinernema carpocapsae nematodes. Late fall is the best time to apply beneficial entomopathogenic Steinernema carpocapsae nematodes against fleas in the soil because during this time of the year temperatures definitely decline and therefore, a large number of larval and pupal stages of fleas prefer to avoid cold winter by remaining 1-2 inch deep in the soil at resting places of animals especially dogs (Photo 1). The spot application of Steinernema carpocapsae at these resting places of dogs during fall can reduce the existing populations both larvae and pupae in the soil, which in turn will reduce future outbreaks of fleas in the spring. For complete elimination of this noxious pest, you can apply beneficial nematodes monthly again in the spring through summer to target overlapping larval and pupal populations of fleas. 

Dogs are the most susceptible hosts of the fleas

Photo 1. Fleas feed on dogs

Recommended rates of beneficial entomopathogenic Steinernema carpocapsae nematodes for different sizes of area.

Area  in sq. ft.       =          Number of nematodes required

1………………………………………..23,000

100………………………………..2,300,000

500…………………………….. 11,500,000

1,000…………………………..  23,000,000

43,560 (1 Acre)………….1,000,000,000

Research Papers

  1. Glazer, I, Samish, M. and del Pino, F.G. 2005. Applications for the Control of Pests of Humans and Animals. In: Nematodes as biological control agents (ed. Grewal, P.S., Ehlers, R.-U. and Shapiro-Ilan, D.I.) CABI Publishing,  pp 295-315.
  2. Henderson, G., Manweiler, S.A., Lawrence, W.J., Templeman, R.J. and Foil, L.D. 1995. The effects of Steinernema carpocapsae (Weiser) application to different life stages on adult emergence of the cat flea Ctenocephalides felis (Bouche). Vet. Dermatol. 6:159-163.