Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2004
Publication Date: August 1, 2004
Citation: Simmons, A.M., Legaspi, J.C. 2004. Survival and predation of delphastus catalinae (coleoptera:coccinelidae), a predator of whiteflies (homoptera: aleyrodidae), after exposure to a range of constant temperatures. Environmental Entomology. 33:839-843. Interpretive Summary: Delphastus catalinae is a small lady beetle which feeds on the sweetpotato whitefly and on some other whiteflies. The sweetpotato whitefly survives year-round in coastal South Carolina. The D. catalinae predator has shown promise to help control whiteflies. It is not known if this predator can survive moderate winters such as in South Carolina, or how short-term temperature extremes may affect it when it is shipped commercially for biological control for greenhouse or field crops. The influence of temperature on the survival of this predator was determined in the laboratory. Eggs and nymphs of the B-biotype sweetpotato whitefly were used as its food. Over 90% of the adult beetles exposed to temperatures from 41 to 95 oF survived after a one-day exposure to either temperature. However, only about 1% of the beetles survived temperatures of 23 oF or 113 oF. Survival of the pupae stage of the beetle was similar to survival of the adult stage for the one-day exposure period. A population of the adult predator survived over five months with half of the population dying after two and a half months when the beetles were held at 77 oF and fed immature whiteflies. Adult beetles held at 95 oF lived an average of about 1 wk. This information helps in the understanding of which temperatures may affect the survival of D. catalinae during commercial shipment and after release for biological control in the field or greenhouse. Also, it helps to define types of winter temperatures which can affect the survival of this lady beetle.
Technical Abstract: Delphastus catalinae (Horn) is a whitefly predator which has shown promise to help in pest management schemes. One of its hosts, the B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius), survives the moderate winters of coastal South Carolina, but it is not known if D. catalinae can survive such winters. The influence of temperature on the survival of D. catalinae was determined in the laboratory on eggs and nymphs of the B-biotype sweetpotato whitefly. Over 90% of the adult beetles exposed to constant temperature regimes of 5, 10, 15, 20, 25, 30, and 35 oC for 24 h survived when confined with the whiteflies. The lower and upper thresholds for survival over that duration was around -5 oC and 45 oC, respectively; about 1% of the test population survived. Survival of D. catalinae pupae were similarly affected by the different temperatures when they were exposed to those temperatures for 24 h. Adult D. catalinae survived over 160 d with half of the population dying after 73 d when the beetles were confined on a plant infested with the immature whiteflies and under a constant temperature of 25 oC. Adults beetles held at 35 oC lived an average of about 1 wk. These data provide information on temperatures which may affect the survival of D. catalinae during commercial shipment, and after release for biological control in the field or greenhouse. Moreover, the information helps in determining the ability of D. catlinae to survive relatively moderate winters in the field.