Population Dynamic of Blastopsylla occidentalis Taylor (Hemiptera: Psyllidae), a Psyllid Pest of Eucalypts

Eucalypts host a variety of insect pests among which the psyllid Blastopsylla occcidentalis Taylor is responsible for the degeneration of eucalypt seedlings. This psyllid is present in Cameroon, but no record has been published on the study of its population dynamics and the main factors that regulate its population. Our study aimed to describe the numerical variation of psyllid population and to correlate these variations to the abiotic and biotic factors that may naturally regulate the population of this pest. This study was carried out in Yaounde (Cameroon) from August 2009 to July 2011. The survey took place once a week on 1-year-old 111 eucalypts. During the 2 years of study, a total of 52,341 males and 64,725 females were collected. The population of B. occidentalis showed three periods of psyllid outbreaks each year. Six and five psyllid generations were observed during the first and the second years, respectively. Among the climatic factors, the increase of relative humidity and rainfall led to a decrease of the number of psyllids on the host plant. The number of new buds on host plants was positively correlated with the number of psyllids infesting. Psyllid parasitoids and predators were identified. These results constitute an important step for the elaboration of an integrated pest management against the eucalypt psyllid in Cameroon.