Fitness consequences of intraguild predation between Spodoptera frugiperda (Lepidoptera: Noctuidae) and Ostrinia furnacalis (Lepidoptera: Crambidae).

The introduction of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), into Thailand has significantly altered the dynamics of maize pests. It has overshadowed Ostrinia furnacalis (Guenée) (Asian corn borer) (Lepidoptera: Crambidae), previously the most severe maize insect in Thailand. This transition is postulated to stem from the superior intraguild predation (IGP) capabilities of S. frugiperda. To validate this supposition, we assessed the co-distribution patterns and damage locales of both pests within maize fields and analyzed the IGP's repercussions on their larval growth, survival, and fecundity. Our findings demonstrate that: (i) incidence of O. furnacalis in maize fields is markedly reduced following the introduction of S. frugiperda; (ii) abundance of S. frugiperda and O. furnacalis is negatively correlated in field; (iii) interspecific interactions affect the spatial distributions of S. frugiperda and O. furnacalis on shared plants; (iv) S. frugiperda has lower generation time and higher fecundity; and (v) IGP amplifies the growth rate of S. frugiperda and elevates mortality in O. furnacalis. Moreover, in response to the competitive pressure exerted by S. frugiperda, O. furnacalis exhibited expedited molting and growth without a commensurate increase in size. Our data suggest IGP proficiency underpins S. frugiperda's dominance in Thai maize fields. We propose a niche differentiation on spatiotemporal distribution facilitating the coexistence of S. frugiperda and O. furnacalis. The impact of S. frugiperda on pest management strategies is discussed.

Body size of fungus-growing termites infers on the volume and density of their fungal cultivar.

The body size of an animal plays a crucial role in determining its trophic level and position within the food web, as well as its interactions with other species. In the symbiosis between Termitomyces and fungus-growing termites, termites rely on nutrition of fungal nodules produced by Termitomyces. To understand whether the size of termites and fungal nodules are related to their partner specificity, we quantified the size of termite farmer caste, and the size and density of nodules in termite nests of four genera of fungus-growing termites, and identified their cultivated Termitomyces fungus species based on internal transcribed spacer regions and partial large subunit ribosomal RNA gene sequences. The results showed that the size and density of fungal nodules were different among Termitomyces clades and revealed a constant trade-off between size and density among clades. The nodule size of each clade has low variation and fits normal distribution, indicating that size is a stabilized trait. Moreover, we found larger termite genera cultivated Termitomyces with larger but less numerous nodules. Based on these results, we concluded that there is a size specificity between Termitomyces and fungus-growing termites, which may lead to diversification of Termitomyces as adaptations to different termite genera.

Desiccation tolerance of Termitidae termites in relation to their nest type.

The family Termitidae is renowned for its diverse nesting behaviors, with the evolution of epigeal and arboreal nests hypothesized to increase desiccation stress due to greater exposure to air. However, these nests may also alleviate desiccation stress through humidity regulation. To explore the implications of acquiring epigeal and arboreal nests, we investigated desiccation tolerance traits in 16 Termitidae termite species with varying nest types and analyzed trait correlations. Principal component analysis revealed that termites constructing epigeal and arboreal nests exhibited reduced water loss rates and enhanced survival under desiccated conditions. Furthermore, termites building arboreal nests displayed a notably higher water content. Redundancy analysis demonstrated that nest types accounted for a substantial portion (57.2%) of the observed variation in desiccation tolerance. These findings support the hypothesis that epigeal and arboreal nests in termites are associated with increased desiccation stress and increased desiccation tolerance. These findings highlight the role of nest type in influencing desiccation tolerance mechanisms and water regulation strategies in termites.

Modeling the Growth of Black Soldier Fly Hermetia illucens (Diptera: Stratiomyidae): An Approach to Evaluate Diet Quality.

The black soldier fly (BSF, Hermetia illucens (Linnaeus), Diptera: Stratiomyidae) is an edible insect widely reared by using various types of organic wastes as its diet. Developing tools to evaluate the growth performance of BSF is crucial for improving its production. In this study, we monitored the daily growth of BSF larvae reared with 10 diets with diverse nutritional quality and compared 7 growth models for quantifying growth performance. We found that BSF generally exhibited an S-shaped growth curve and that the Richards model was the best-fitting growth model. We estimated asymptotic growth limit (W∞) and constructed a time-series curve of absolute growth rate (AGR) by using the Richards model. We used Gaussian functions to estimate AGR parameters (maximum AGR, m; timing of maximum AGR, T; the deviation of AGR, d) to evaluate whether these parameters adequately quantify the growth performance of BSF. Correlation analysis showed that the AGR parameters were mostly independent of W∞ but were correlated with the duration of the larval stage, indicating that W∞ and the AGR parameters respond to different dietary factors. The results of pairwise comparisons showed that the diets rich in carbohydrates and protein had high W∞, m, and d, and early T. The diets with low levels of carbohydrates had low W∞, and the diets with low levels of protein had low m and d and delayed T. We conclude that the parameters estimated by the Richards model could be effective indices for evaluating the growth performance of BSF and their diet quality.