The
two-spotted leafhopper, Sophonia rufofascia, originally described in southern
China, was first discovered in Hawaii in 1987, and has since spread to all major Hawaiian
islands. This insect is extremely polyphagous,
attacking over 300 species of host plants in 83 families (Fukada 1996). Among the host
plants, 68% are economically important fruit, vegetable, and ornamental crops; 22% are
endemic to the Hawaiian islands (including 14 rare and endangered species); and 10% are
exotic weeds. Many economically important crops attacked in Hawaii are also grown in other
areas of the Pacific and Caribbean basins. The recent discovery of resident breeding
populations of the two-spotted leafhopper in ornamental, vegetable, and fruit crops in
California adds urgency to the need for biological control measures to curtail the spread
of this insect. The photo above shows two S. rufofascia mating
(back to back).The goal of our research is to initiate a classical biological control
program against this invasive leafhopper. This program focuses on exploration for and
identification of undescribed or previously described but unexploited natural enemies
(parasitoids) from southern China, the most probable native home of the leafhopper. We
will also conduct introduction, quarantine, and host testing of promising parasitoids, as
well as laboratory studies to ascertain the environmental compatibility and efficacy of
the parasitoids in suppressing leafhopper populations.
During the past 8 months (July 1, 1998 - March 1, 1999), we studied the bionomics and
rearing feasibility of Sophonia rufofascia leafhoppers in Hawaii. Sophonia
rufofascia was successfully reared on green ti and guava plants for 2 generations.
Adult S. rufofascia becomes reproductively mature 10 - 14 days after emerging ;
each female lays 1 - 2 eggs per day. The egg takes about 4 weeks to hatch; and nymphs take
7 - 8 weeks to develop to adults. These baseline data form a solid foundation for further
work on parasitoid exploration, rearing, and quarantine testing. Also, the long
developmental time of leafhopper eggs suggest that egg parasitoids (e.g., Chaetomyma sp)
may be effective in controlling the leafhopper populations because of the potentially long
parasitoid exposure windows. The development of procedures for rearing the host, Sophonia
rufofascia, is the first step to successfully rearing parasitoids imported from China.
Currently, one species of egg parasitoid (Chaetomyma sp) has been collected from
eggs of a Sophonia leafhopper ( Sophonia furnalinca) in South China
(Guanzhou province). After the exact species identity is confirmed, we will import the
collected parasitoid to the quarantine laboratory of the Hawaii Department of Agriculture,
and conduct tests there for its efficacy in parasitizing S. rufofascia. We hope
that by the end of the project, we will have successfully introduced an effective egg
parasitoid into Hawaii for control of Sophonia rufofascia. |
