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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #212818
Title: Should the Waterhyacinth Mirid, Eccritotarsus catarinensis (Heteroptera: Miridae), be Considered for Release against Waterhyacinth in the United States of America?

Author
item COETZEE, J - RHODES UNIVERSITY
item BYRNE, M - UNIV. WITSWATERSRAND
item HILL, M - RHODES UNIVERISYT
item Center, Ted

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2008
Publication Date: 1/1/2009
Citation: Coetzee, J.A., Byrne, M.J., Hill, M.P., Center, T.D. 2009. Should the Waterhyacinth Mirid, Eccritotarsus catarinensis (Heteroptera: Miridae), be Considered for Release against Waterhyacinth in the United States of America?. Biocontrol Science and Technology, 19:1, 103-111.

Interpretive Summary: State and Federal agencies spend millions of dollars on herbicides and mechanical harvesters attempting to control water hyacinth, an invasive aquatic plant. Effective biological control could save a large portion of this expense and reduce the environmental hazards associated with the wide-scale application of herbicides into potable water supplies. A sap-feeding bug released in South Africa to aid in the control of waterhyacinth might also be useful in the United States. Unfortunately, feeding trials conducted under artificial conditions indicated that it might also feed on a native North American plant (pickerelweed), which is related to waterhyacinth. Additional tests conducted under natural conditions indicated that the risk of harm to this plant was minimal. Even though the perceived risk from this insect was negligible relative to the damage to pickerelweed from scouring of drifting waterhyacinth mats and associated herbicide treatments, any risk would be ill advised if the bug did not affect control. Also, the cost associated with implementing an ineffective biological control agent would be wasted. However, effects can oftentimes be quite subtle becoming observable only over prolonged periods. These subtle effects can be magnified and more readily observed when the targeted plant is subjected to competition from other plant species. Previous study showed that the bug did indeed debilitate waterhyacinth and that pickerelweed was at minimal risk. This study demonstrates that the bug would not occur to the north beyond the southern states of the US and would be unlikely to establish populations in the Northeast where pickerelweed exists but waterhyacinth does not. Hence, this insect may, in fact, be suitable for use as a biological control agent.

Technical Abstract: At least one and as many as seven biological control agents have been released against waterhyacinth (Eichhornia crassipes (Mart.) Solms) in no less than 30 countries, with varying degrees of success. A mirid, Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae), the most recent agent released, has been shown to be damaging to the plant on the African continent. It could be useful in the USA where waterhyacinth remains a problem, but its introduction has remained in doubt because it developed on Pontederia cordata L. (pickerelweed), a plant indigenous to the USA, during laboratory host specificity trials. In contrast, it has failed to establish in the field in South African field on pure stands of pickerelweed, and only light spillover feeding occurred where the two plants coexisted. This suggests that its use of P. cordata as a host was a laboratory artifact and that it may indeed be suitable for release in the USA. Additional climate matching and thermal physiology studies predict that cold winter temperatures would limit the mirid to the southern states. Even though some spillover feeding on pickerelweed might result where the two plants co-occur, the risk of population level effects seem minimal and the risk to more northern pickerelweed nil. The benefits, including improved habitat for pickerelweed, associated with further suppression of waterhyacinth, probably outweigh the minimal risk of collateral damage to pickerelweed.