Feeding preferences and related types of behaviour of Neomegalotomus parvus

Laboratory studies with Neomegalotomus parvus (Westwood) (Hemiptera: Alydid ae) with one nymph per Petri dish in multiple-choice tests indicated that s eeds of pigeon pea [Cajanus cajan (L.) Mills.], lablab (Dolichos lablab L.) , and soybean [Glycine max (L.) Merrill] were visited before seeds of commo n bean (Phaseolus vulgaris L.) and rice (Oryza sativa L.). The percentage o f individuals engaging in dabbing/antennation resulting in probing, and per centage probing resulting in feeding, were higher on common bean (97%) and pigeon pea (87%) seeds than on lablab (55%), soybean (50%), or rice (5%) se eds. No significant differences were found in preference (number of flanges ) among pigeon pea, common bean, and lablab, and preference (insects on foo ds) varied throughout the assessment period (5 d). In tests using 10 nymphs per dish, pigeon pea was the preferred food (number of flanges and insects on plants) throughout the period (5 d). In no-choice tests, the average du ration of a feeding session and the longest feeding session were greater on lablab and common bean than on pigeon pea, soybean, or rice seeds. The num ber of feeding sessions was greater on seeds of common bean, pigeon pea, an d soybean than on those of lablab or rice. Laboratory tests with N. parvus adults indicated that pigeon pea seeds were located faster, followed by com mon bean, soybean, and rice. When pods were tested, dabbing/antennation tim e was shorter on pigeon pea than on soybean, and probing time was longer on soybean than on pigeon pea or common bean. On pigeon pea, 100% of the inse cts probed the host, while on common bean and soybean pods, and on rice pan icles, these values dropped to 71.8%, 46.0%, and 10.5%, respectively. Adult s showed similar feeding times on pigeon pea, common bean, and soybean pods , but did not feed on rice panicles. Electronmicroscopical analysis showed the presence of two apical lobes with 12 peg sensilla on the labial tip. Se nsillum tips were stained with silver nitrate solution, indicating a permea bility of the cuticle and, therefore, their function as taste receptors.