Relationships between leaf trichome characteristics and field resistance to cassava green mite (Mononychellus tanajoa (Bondar)

Experiments were conducted at Ibadan, Nigeria to assess the effect of leaf trichome characteristics (pubescence intensity index, length, and orientation) on field resistance of cassava to the green spider mite, Mononychellus tanajoa (Bondar). There were significant (P < 0.01) differences in M. tanajoa density, damage score and leaf trichome characteristics among the cultivars. During the dry season (February, 1993 and 1994) and the early part of the rainy season (May, 1993), there were significant (P < 0.01) negative correlations between pubescence intensity index on the top leaves (leaf 3) and mite damage. Significant negative correlations were also obtained between trichome length and damage in the dry season (February, 1993) (P < 0.05), and between trichome orientation and mite damage in the rainy season (May, 1993) (P < 0.01). Correlation between pubescence intensity index and mite density on the top leaves was significant and positive only in the "middle" of the rainy season (August, 1993). A significant (P < 0.01) negative correlation was obtained between trichome orientation and mite density in the dry season (February, 1993). The results suggest that, during the dry season, a high pubescence intensity significantly reduces leaf damage by M. tanajoa through mechanical disturbance of movement and feeding. Trichome length is more important than trichome orientation in cassava resistance to M. tanajoa

Residual toxicity of acaricides to Galendromus occidentalis and Phytoseiulus persimilis reproductive potential

Understanding the effects of pesticide residues on leaf surfaces through time on phytoseiid mites is important to their successful integration into augmentation and/or conservation programs. The residual toxicities of fenpyroximate (Fujimite ®), acequinocyl (Kanemite ®), etoxazole (Zeal ®), spiromesifen (Oberon ®), bifenazate (Acramite ®) and abamectin (Agri-mek ®) on leaflets to Galendromus occidentalis (Nesbitt) and Phytoseiulus persimilis Athias-Henriot (Acari:Phytoseiidae) were assessed 3, 6, 10, 14, 17, 24, 30 and 37 days post treatment. Impacts on mortality, fecundity and fertility were determined following 3 days of exposure to each leaf surface residue interval. Percent mortality and total effects (E) on adult female reproductive potential thus measured were used to assess each acaricide's persistence. Based on mortality, fenpyroximate was considered slightly (from 5 to 15 days) persistent for both species by IOBC standards, while abamectin was also slightly persistent for P. persimilis only. The remaining acaricides would be classified as short lived (less than 5 days) for both species. Persistence classified by considering E suggest that fenpyroximate and etoxazole would be the least compatible with G. occidentalis and P. persimilis. Both were persistent (longer than 30 days). Bifenazate and spiromesifen were slightly persistent to both predators. Acequinocyl was slightly persistent to G. occidentalis, but short lived to P. persimilis. Abamectin was slightly persistent to P. persimilis, but short lived to G. occidentalis. Consideration of both direct and side effects of these acaricides will improve pesticide selection, anabling better conditions for Phytoseiid conservation and augmentation. © 2006 Elsevier Inc. All rights reserved

Data from: Recurrent sublethal warming reduces embryonic survival, inhibits juvenile growth, and alters species distribution projections under climate change

The capacity to tolerate climate change often varies across ontogeny in organisms with complex life cycles. Recently developed species distribution models incorporate traits across life stages; however, these life-cycle models primarily evaluate effects of lethal change. Here, we examine impacts of recurrent sublethal warming on development and survival in ecological projections of climate change. We reared lizard embryos in the laboratory under temperature cycles that simulated contemporary conditions and warming scenarios. We also artificially warmed natural nests to mimic laboratory treatments. In both cases, recurrent sublethal warming decreased embryonic survival and hatchling sizes. Incorporating survivorship results into a mechanistic species distribution model reduced annual survival by up to 24% compared to models that did not incorporate sublethal warming. Contrary to models without sublethal effects, our model suggests that modest increases in developmental temperatures influence species ranges due to effects on survivorship