Prediction of the geographic distribution of the psyllid, Arytinnis hakani (Homoptera: Psyllidae), a prospective biological control agent of Genista monspessulana, based on the effect of temperature on development, fecundity, and survival.

The psyllid, Arytinnis hakani (Loginova), is a prospective biological control agent of Genista monspessulana (French broom), an invasive shrub originating from western Europe. It is a multivoltine species that is not known to diapause. The insect is established in Australia, where it appears to cause heavy defoliation and mortality of the target weed, except at warm sunny sites. This suggests that bright light or high temperatures may hamper the agent. We measured the effect of temperature on development rate, survival, and fecundity of the psyllid to determine its suitable temperature range. Intrinsic rate of increase was highest near 22°C, and there was no population growth at the extremes of 5°C and 26°C. Net reproductive rate was highest at 16.5°C. Fecundity was highest at 22°C, and decreased to half at 16°C and at 27°C. Adult female longevity decreased with increasing temperature over the range studied. Nymphal survivorship was highest at 16°C and dropped to 0% at 5°C and 26°C. Eggs were able to complete development in 83 d at 5°C, but with only 20% survivorship versus 78-95% survivorship at higher temperatures. For populations with a stable age distribution, only 2-3% of the population is in the adult stage. Climate modeling using CLIMEX indicated that the geographic distribution of the psyllid is constrained by high temperature stress in Australia. The psyllid is predicted to be suitable in coastal California but not in the Sierra foothills.