Climate-induced range shifts of invasive species (Diaphorina citri Kuwayama).

BACKGROUND: The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a destructive, invasive species that poses a serious threat to the citrus industry wherever it occurs. The psyllid vectors the phloem-limited bacteria 'Candidatus Liberibacter americanus' and 'Ca. L. asiaticus', causal agents of the incurable citrus greening disease or huanglongbing (HLB). It is essential to understand which regions and areas are suitable for colonization by ACP to formulate appropriate policy and preventive measures. Considering its biology and ecology, we used a machine learning algorithm based on the MaxEnt (Maximum Entropy) principle, to predict the potential global distribution of ACP using bioclimatic variables and elevation. RESULTS: The model predictions are consistent with the known distribution of ACP and also highlight the potential occurrence outside its current ecological range, that is, primarily in Africa, Asia and the Americas. The most important abiotic variables driving the global distribution of ACP were annual mean temperature, seasonality of temperature and annual precipitation. CONCLUSION: Our findings highlight the need for international collaboration in slowing the spread of invasive pests like D. citri. © 2022 Society of Chemical Industry.

Impact of Diamondback Moth Density and Infestation Timing on Broccoli Yield.

The diamondback moth (DBM), Plutella xylostella (L.) (Lep.: Plutellidae), is an important pest of broccoli (Brassica oleracea L. var. italica Plenck). Few studies have focused on the real DBM impact on broccoli yield. We performed greenhouse studies to assess the effect of DBM densities and infestation timing (at pre-heading, heading, or during the entire cycle) on broccoli head weight. Polynomial trend analysis revealed a downward linear response of head weight to DBM densities, indicating that broccoli is susceptible to DBM attack. As for the infestation timing, infestations during the pre-heading stage significantly impacted head weight, whereas the same did not occur for infestations during the heading stage. DBM density did not affect plant height or total leaves but was upward-related to plant defoliation, and head weight correlated negatively with plant defoliation. These findings indicate that pre-heading is the determining stage for head weight loss of plants under DBM attack. In order to prevent quantitative losses, efforts for DBM management should be focused on this particular stage.