Riparian terrestrial insects face floods or accidental water exposure; however, their ability to fly off the water surface is unclear. Interspecific variation in takeoff latency and probability was evaluated in 25 beetle species. Non-riparian species did not initiate flight from the surfaces of experimental lentic water, whereas 19 riparian species did. Takeoff latency varied greatly, with a remarkable influence of shoreline distribution and body size. High-speed videography demonstrated that, upon landing, Tachyura laetifica (Carabidae) clearly adhered to the water surface and progressively detached from the interface by pulling its body upward. In contrast, upon landing, Thinodromus eminens (Staphylinidae) quickly stood in position and took off almost immediately. Under reduced surface tension, takeoff performance declined, indicating the importance of a stable standing position for takeoff. In the laboratory, both species demonstrated takeoff under a low-velocity flow. The results suggest that in riparian beetles, takeoff from the water surface is a common behavioral response, which may help them fly off rapidly to avoid water-level fluctuations or predation risk.
Understanding the foraging behavior of wild solitary bees is essential for elucidating their ecological roles and responses to floral resource dynamics in agricultural landscapes. Among these bees, species of the genus Megachile are recognized as effective pollinators of several crops, yet information on their temporal foraging patterns and behavioral variation in sesame (Sesamum indicum L.) remains limited. This study investigated the diurnal activity patterns, visitation behavior, and foraging performance of Megachile bees in sesame agroecosystems of West Bengal, India, during two consecutive pre-kharif (February-May) seasons (2022–2023). In addition, the broader assemblage of floral visitors was documented to place Megachile foraging activity within the context of the floral visitor community. A total of 39 insect species were recorded visiting sesame flowers, with Hymenoptera representing the dominant group (61.54
The physiological state of animals can significantly influence how they interpret and respond to chemical cues. However, whether larval responses to conspecific volatiles are context-dependent remains poorly understood. In this study, we evaluated how nutritional state modulates larval responses to volatile chemical cues in Chilecomadia valdiviana (Lepidoptera: Cossidae) using Y-tube olfactometer bioassays. Larvae were exposed to dodecyl acetate (12:OAc), a compound previously identified in larval secretions, an extract of larval secretions, and a combination of both under fed and fasting conditions. The bioassays included: (1) 12:OAc versus control; (2) larval extract (at 1 and 10 larval equivalents) versus 12:OAc; and (3) extract plus 12:OAc versus control. Nutritional state influenced both overall responsiveness and stimulus preference. Fed larvae exhibited a stronger response to the extract at the higher concentration (10 larval equivalents) than to 12:OAc, whereas short-term fasting (24 h) increased responsiveness to 12:OAc as well as the combined stimuli. However, prolonged fasting (5 days) markedly reduced overall responsiveness and led to avoidance of both 12:OAc and the combination. These results indicate that larval responses to volatile cues are not fixed but are modulated by physiological context and stimulus concentration. Our findings support the notion that chemical signals can function as context-dependent modulators rather than invariant attractants, highlighting the context dependence of larval responses to conspecific volatile cues.
Zygogramma bicolorata is a specialist herbivore used worldwide to control the invasive weed Parthenium hysterophorus. A major concern is that after destroying the target weed, these agents might feed on non-target plants. This study investigates how food deprivation influences cannibalism in Z. bicolorata and whether starvation forces host range expansion. When starved adults were offered host leaves and conspecific eggs, they preferred Parthenium when available. However, as phytophagous food decreased, cannibalism on eggs increased (GLMM: χ2 = 187.34, P < 0.001), with females consuming nearly twice as many eggs as males (4.8 ± 0.3 vs. 2.9 ± 0.3 eggs; P < 0.001). Crowding intensified this; at higher densities, beetles consumed 15.6 ± 0.6 eggs versus 3.8 ± 0.3 at lower densities (P < 0.001). Beetles also preferred injured over healthy conspecifics, being 4.3 times more likely to consume injured eggs (odds ratio = 4.26, P < 0.001). Critically, when deprived of host and exposed to non-host Tagetes sp., beetles did not feed on non-host plants. Instead, they turned to cannibalism, consuming 13.0 ± 0.5 eggs versus 1.2 ± 0.3 eggs with host present (P < 0.001). Predator exposure further intensified cannibalism, with beetles consuming 29.3 ± 1.2 conspecifics versus 16.8 ± 0.8 in controls (P < 0.001). Our findings demonstrate that in laboratory conditions, Z. bicolorata responds to food scarcity by increasing cannibalism, not by expanding host range to non-target plants. Under these controlled conditions, cannibalism appears to serve as a short-term survival strategy that reinforces host specificity. Although these laboratory results cannot be directly generalized to field conditions, they alleviate concerns about non-target feeding in the contexts tested and support continued investigation of this beetle for weed control under natural conditions.
Ambient temperature strongly influences behavioral performance in ectothermic animals. Food-related aggression, as a social interaction centered on a defined and controllable resource, provides an ecologically relevant and experimentally tractable framework for studying conflict. However, how offensive and escape behaviors during such competition vary across thermal conditions and genetic backgrounds remains incompletely understood. Here, we compared food-related competitive behaviors in two laboratory strains of male Drosophila melanogaster, Canton-S and w1118, under two assay temperature conditions. We quantified wing threats, physical contact, and withdrawal behaviors. Overall offensive actions were lower under the cooler assay condition ( 18 °C) than under the warmer assay condition ( 25 °C), but genotype-related differences were most evident under the cooler condition. Under 18 °C, Canton-S males exhibited higher levels of offensive behavior than w1118 males, whereas these genotype differences were less pronounced under 25 °C. Wing threat displays showed relatively weak genotype differences, whereas physical contact behaviors showed clearer condition-associated and genotype-related variation. Locomotor assays revealed genotype-dependent differences under the cooler condition, indicating that the reduced offensive behavior of w1118 males cannot be explained solely by general locomotor suppression. Together, these results suggest that food competition-related behaviors differ between male fruit fly strains across assay conditions, with genotype-related differences being most evident under cooler conditions.
