Artificial diets for rearing the coconut hispine beetle Brontispa longissima and its parasitoid Asecodes hispinarum

Abstract

We tested artificial diets for rearing the coconut hispine beetle, Brontispa longissima, a serious invasive pest of coconut (Cocos nucifera) in Southeast Asia. We examined three artificial diets that were identical except for their agar content. The survival rate from hatching to adult emergence was 26.0% when beetles were reared on a ‘soft diet’ (20 g/l agar), 16.0% on a ‘hard diet’ (40 g/l agar), and 41.0% on a ‘mixed diet’, in which the hard diet was used for the first instar and the soft diet for later instars. Females raised as larvae on the mixed diet and then as adults on the soft diet laid few eggs, which did not hatch. However, females reared on the mixed diet as larvae and then on fresh leaves as adults consistently laid eggs that hatched. We then examined the suitability of B. longissima larvae reared on the mixed diet as hosts for the larval parasitoid Asecodes hispinarum, a specialist parasitoid of this beetle. Of the oviposited hosts, 75.0% became mummified and 41.7% produced adult wasps. These results indicate that the mixed diet may be useful for rearing B. longissima larvae as hosts for the rearing of A. hispinarum.

A Comparison of Artificial Diets for Mass Rearing <I>Brontispa longissima</I> (Coleoptera: Chrysomelidae) as Hosts for the Larval and the Pupal Parasitoids

“…In the present experiment, the proportion of sixth-instar larvae with Diet C was lower than with the control diet. These indicate that Diet C is less optimal than fresh coconut leaves as food for B. longissima, but Diet C nonetheless enhanced the survival rate compared with the other diets in this study (Table 2) and with our previous diets ( Table 2; Ichiki et al 2009Ichiki et al , 2011.…”

“…The artiÞcial diets were prepared by modifying the diet reported by Ichiki et al (2009). Ichiki et al (2011) developed two artiÞcial diets made from mature coconut leaf powder and orchard grass powder as the main ingredients, but the survival rates of beetles that were fed these diets were lower than those that were fed the diet made from young coconut leaf powder reported by Ichiki et al (2009).…”

“…The B. longissima population was collected on Ishigaki Island, Okinawa, Japan, and we reared this insect as described by Ichiki et al (2009). A. hispinarum was obtained from B. longissima collected in Vietnam.…”

“…To make the control, all ingredients were blended and then autoclaved for 16 min at 121ЊC, after which 0.5-g amounts were spread on a woven polyethylene sheet (60 mesh, 3 ϫ 3 cm). A hard diet containing 4 g agar per 100 ml was provided to the Þrst-instar larvae of B. longissima, and a soft diet containing 2 g of agar per 100 ml was provided after 50% of the surviving larvae had molted into the second instar, as described by Ichiki et al (2009).…”

“…Unfortunately, it is difÞcult to obtain sufÞcient quantities of fresh coconut leaves for use in massrearing programs. For this reason, we have tried to develop an artiÞcial diet for B. longissima to serve as an alternative food source (Ichiki et al 2009(Ichiki et al , 2011. Thus far, we have developed three kinds of artiÞcial diets: these use the young coconut leaf powder, mature coconut leaf powder, and orchard grass (Dactylis glomerata L.) leaf powder as the main ingredients.…”